Can light GA aircraft with FDs or couplers use the RVR reduction clause on an ILS?

FAA Order 8400.13C outlines these procedures. Section 7 c outlines the requirements for this procedure. Most of these affect the airport facilities or procedures themselves, and section 5 b outlines the IAP requirements for aircraft:

  Aircraft equipped with an operable FD, or AP with an approach coupler, or HUD which is certified for operation to a minimum of 200 feet HAT are eligible for this operation.

There is also a note under 9 b:

  Single pilot operators are prohibited from using the FD to reduced CAT I landing minimums without accompanying use of an AP with an approach coupler or HUD.

So it would appear that having a FD is not entirely sufficient; a pilot with a FD can use the reduced minimums if they also have one of the following:

AP with approach coupler
HUD
Copilot


Many employees are not screened. This article, written in the aftermath of the LAX "dry ice bomb" incident, goes in detail about the levels of security employees face.

Ramp workers like 28-year-old Dicarlo Bennett, who was charged Thursday with two counts of possessing a destructive device in a public place, have access to just about anywhere in the airport. And though they must pass a 10-year background check before they’re hired, airport workers generally do not need to clear security when they arrive for their shifts.
...
Melendez said it’s not possible to check every employee when they arrive each day, especially when many of those workers have access to potentially dangerous or disruptive items once they’re on the job. (Dry ice is regularly used by caterers to keep food cold.)
...
Arif Alikhan, deputy executive director for homeland security at LAX, said the key is to have many layers of security. He said unannounced security checks are common, and inspectors might take a look at an employee’s lunch box or bags. Employees are asked to question who enters secure areas of the airport, and told to never hold doors open for each other.

After another incident in which employees smuggled firearms and drugs onto a Puerto-Rican bound flight, the Department of Homeland Security did a feasability study on 100% employee screening. Part of their findings were:

The concept of 100% airport employee screening is feasible. However, we do not believe it is realistic at this time. Regardless of the amount of funding, resources, and effort allocated toward this endeavor, vulnerabilities will persist. While the intelligence, screening, and law enforcement communities continue to make progress in addressing these vulnerabilities, 100% airport employee screening cannot entirely bridge existing gaps. As TSA changes its regulatory requirements, technology improves, and airports upgrade existing security measures, implementing this concept would be more realistic and should be revisited.

If you do a Google search on the subject, you will find numerous documents from large airports across the country detailing their procedures, most of which merely have to do with background checks and security badges.


Does runway 32/33R at Madrid actually have a kink in it?

An interesting feature of your question is the apparent double-exposure of runway number in your image. And I suspect it will also account for/explain why you see a kink in an image.

Occasionally, runways change number. The reason for this is basically that runways only have 36 possible designations (1-36) however a runway designated 18 may be orientated anywhere from 175-184 degrees. Usually the actual orientation of the runway is rounded to the nearest 10. hence, a runway pointing at 184 degrees would be designated "Runway 18".

Magnetic variation drifts over the years (eg, 10 years ago Southern UK was +3 degrees, now it is +1). This may make a runway which was once 184 degrees magnetic now 186 degrees and that would require its designation to change from "Runway 18" to "Runway 19".

Now, as for your image, I would guess that Google have taken a grab when it was Runway 32, and (at least partially) again once it had been re-designated (and repainted!) Runway 33. This is backed up with the airport's wikipedia article:

  On 20 September 2012, both runways 15/33 were renamed as 14R/32L (the longest) and 14L/32R (the shortest).

The act of stitching images together, and the image processing algorithms in use, mean you get kind of a partial of one image and partial of the other. It is almost certainly not there in real life, and thus has no effect on the pilot's handling around that runway.


How does the automatic battery cut off logic prevent complete battery discharge on ground in the A320?

According to this page: http://theflyingengineer.com/projects/airbus-tech/electrical/

A Battery Automatic cut-off logic prevents the batteries from discharging completely when the aircraft is on the groung [sic] (Parking).
Automatic battery contactors open when :

The a/c is on the gorund [sic].
The BAT P/b s/w’s are at AUTO
The main power supply (EXT PWR+GEN) is cut off
Battery Voltage is low.

Nothing should automatically disconnect the batteries from the corresponding HOT BUS, so if something is left on the HOT BUS it would continue to drain the battery.


Why is being a commercial pilot stressful?

The stress comes from everything about the job that isn't actually flying the plane.

Dealing with crew scheduling is the #1 cause of stress.  If your phone rings with that special ringtone you assigned to them, you know nothing good is going to come of it.  These calls often end with reassignments, changed overnights, different crew members and sometimes extensions into days off.
Dealing with a stubborn dispatcher who, despite the mess of storms on your route, refuses to give you an extra 500# contingency fuel.
Dealing with pressure for on-time departures.  This usually comes from a gate agent because they generally are the ones who get the short end of the stick if we push late.  This can be exacerbated by agents who know about certain "tricks" to fool the system into thinking you pushed, which are often specifically disallowed by flight operations.
Winter operations.  Figuring out where de-ice happens, what special flow control might be in effect and managing holdover times can be a headache, particularly at unfamiliar fields.
Spring and summertime.  Never a moments rest during cruise but instead a constant look on the horizon and the radar and requesting deviations from every controller you talk to.  These seasons often have days with widespread thunderstorm activity.  These storms for the most part must be avoided and sometimes require constant coordination with controllers to deviate off-route to go around them.  This creates fatigue more than stress, but the two have a way of feeding back on each other.
Holding.  Do we really have the gas to be doing this?
Diverting.  Coordinating with dispatch, maintenance (if needed), operations at the field, ATC and passengers.
Timing out.  Hey folks, sorry we diverted but now we timed out, we're staying the night here.
Crew scheduling, again, to get hotel rooms and find out just how bad this day screwed our schedules for the next few days.
That once yearly visit to the AME where you are reminded just how bad your airport junk food diet is and where exactly "hypertension" starts.
Commuting.  It is fairly common that pilots do not live in their base and live far enough away that the commuting means jumpseating or non-rev flying to get to work and back home.  Depending on where you live you can often encounter oversold flights, competition for the jump seats and little backup options for same-day travel (e.g. not flying in the day before your trip).  Not making it work can have consequences depending on how hard you tried to make it work and how good your union contract and chief pilots are.

Of note, I never found actually flying the plane stressful including operations in low visibility and high winds.  Those are the things that kept the job interesting and I quite enjoyed them.  Having people in the back was also never stress inducing.  As long as I flew safely and kept myself alive, the passengers would end up that way also.  I was mindful of the passengers in selecting alternate cruise altitudes for ride conditions and requesting shortcuts from ATC to make up time but those are not stressful things to do.


Can planned runway closures prevent a plane from leaving an airport?

There is actually a really good example of this...

In 1994 it was decided that the infamous Meigs Field would be demolished and turned into a park. (I say infamous because for all of us young flight simulator aficionados this is the home airport of Microsoft Flight Simulator).

On a Sunday night, March 30, 2003, the Mayor Daley of Chicago ordered the runway bulldozed by gouging huge X's into the runway itself. This was done in the middle of the night with many aircraft still based on the field. No notice was given to the FAA or the owners of aircraft still on the field. In fact, an inbound flight had to be diverted by air traffic control because of equipment on the runway.

You can imagine what kind of excrement storm this stirred up. In the morning of March 31, 2003 at a press conference Daley defended his actions by saying that it would have saved the city of Chicago years of court battles over closing the airport. Luckily the aircraft at the field were allowed to depart from the 3000' taxiway that ran adjacent to the runway.

In this case, the worst the FAA could do was fine the city of Chicago \$33,000 (\$1,100 per day) for closing an ILS procedure without a 30 day notice. Later it was found that they misappropriated FAA funds to demolish the runway and build the park and that had to be paid back, but there were no legal implications of this. The airport was not under federal funding and the city was technically within its rights to close it.

You can read more about it on Wikipedia

The point is that airports are often owned by the city in which they reside, or sometimes the state, at least in the U.S. The FAA releases many guidelines for airports to make them safe, and even has an "airport certification program" for certifying part 139 operations, however these are done through "orders" and guidelines, not much in the way of FAR's.

ATC, if federally operated, must comply with the regulations that apply, including giving NOTAM information for planned closures, or even NOTAM's for closures that are not planned, such as runway debris or accidents closing runways.

So really when you get down to it, the city that owns the airport can close runways (or the entire airport) whenever they want, and yes this may strand aircraft. Usually if the airport is closed unexpectedly and aircraft are still there, they will be allowed to take off from taxiways or grass strips. Worst case scenario the wings will have to be removed and it will need to be trucked out, at least for GA operations.

Depending on the Ops Spec for the airline, it may also allow the aircraft to take off from a taxiway. Usually something like that is done without passengers on board though.

So to address your specific questions...

Is an airport required to give notice to pilots (or aircraft owners) about planned construction? No, there is no requirement for this. Usually what happens is airports don't give adequate notification and it agitates owners, but it all works out in the end.

For example, can an airplane ever be stranded while airport construction is occurring? Yes, at Meigs originally owners had to fight to be allowed to take-off. Many aircraft where going to be scrapped as they were too expensive to move by truck, and owners didn't want to pay. The city didn't want to pay, and the insurance company didn't want to pay, so that would have kicked off a big set of lawsuits for the city.

Closing runways can't always be avoided, for example when there is an accident, weather (flooding, snow, ice), earthquakes, etc. It happens and the system "works" around it when it does.


Where is the term *pro rata* defined as it is used in 61.113(c)?

pro rata in law generally means according to a calculation or apportionment formula - in the context of the FARs that formula is generally assumed to be $\left(\frac{1}{nOccupants}\right)$ as Hugh noted.
I actually went on a dive through FAA counsel opinions on how they deal with the pro rata bit and found nothing applicable to this situation, so what follows is an interpretation crafted out of my own slightly deranged mind, but it seems sensible to me.

  Interestingly while digging around I found nothing in the FARs or interpretations that would seem to preclude a more complex formula for pro rata share than "divide by the number of people in the plane", but neither is there anything I can find to support doing so, and I imagine it would be much harder to justify to your local FSDO if questions came up.
  For the sake of simplicity (and our collective sanity) let's stick with "simple division" as the formula.

The FARs specify that the pilot may not pay less than their pro rata share of operating expenses associated with the flight.  So, if we have 4 occupants of the aircraft (Mom, Dad, Baby, and Pilot) and they go for a hundred-dollar hamburger the simple division method says pilot cannot pay less than one-fourth of the operating expenses associated with the flight.  If we say the expenses work out to be \$100 (for the sake of easy math) the pilot has to pay at least \$25.

The FAA doesn't much care where the rest of the money comes from because it's implicit in the regulations that the pilot isn't keeping it (the money would be going into the hands of the FBO for fuel, oil, ramp fees, etc.) -- Mom & Dad could pay $37.50 each (covering themselves plus the baby) or split it up between themselves in any other way they wish and this is still acceptable under the regulations as long as the pilot has paid their pro rata share of the expenses.

The pilot can certainly pay more than the simple-divison pro rata share of expenses (and generally that's the most equitable option - figure out who's paying, divide by that number, and make sure the pilot is in the "paying" group to stay on the right side of the regulations).
In your example you would split the cost up among the three adults (each paying $33.33, and the pilot generally kicking in the extra penny).

The same logic in both of these arguments would apply if we weren't talking about a baby, but rather a third friend that you all decided to treat to a trip.


How do single GA pilots prevent boredom during long flights?

Not long ago, I had my longest flight as a PPL: about 4 hours from Dallas, TX to Kansas City, MO, in a 172, facing a steady headwind the whole way, so making a ground speed of less than 90kts.

I ran checklists about twice as often as normal, and re-did my fuel calculations very regularly (in part because of the extremely slow progress).

I listened to the ATC frequency, and tried to build a good mental picture of all the planes around me.

I went through every single setting and option on my MFD glass cockpit and iPad.

I watched the scenery, both for visual navigation (despite my GPS), and just to admire the view.

Even after all this, the flight was pretty boring near the end, and I'm glad I don't do flights that long very often.


What would happen if the elevators were set to opposite angles?

This would be an elevon application (ailerons + elevator).  Found on flying wings and deltas.  Theoretically possible on a standard tail.

With elevons, one up and one down will roll the aircraft with out pitching it.  Interesting that this can be done from the front, back, or center of the aircraft.

Someone may wish to correct me, I believe Burt Rutan put both elevator and aileron function in the canard of one of his planes to simplify the control linkages.

So, as a designer, yes this is possible.


What is the best combination of airfoil shape for flight in ground effect over water?

There are three considerations for this design:

Airfoil shape
Aspect ratio
Dihedral/Anhedral

Airfoil shape: high lift undercambered thick and very forgiving - good idea near the ground
      Gottingen 436, NACA 4412

Low aspect ratio: lower stall speed, better compression lift from ground effect, more
     stable in pitch

Anhedralled wings:  this actually provides more roll stability in ground effect as the
      LOWER wing has more lift.  Anhdralling also helps "trap" more air underneath the wings
      for greater lift.

Ground effect designs would be similar for travel over flat land or water.  Good info in links
provided by @mins and @Juan Jimenez.


The radius of the leading edge as a percentage of chord.


New Research: VGs increase lift to drag ratio up to 880%. Does it work for flaps too?

Graph C tells the story.  Better to go with slats and flaps.  Vortex Generators remain valuable to alter the airflow characteristics of a section of the airfoil or control surface.

Drag producing and lift destroying chaotic turbulence on the upper rear of the wing appears to be reduced by the Vortex Generators at higher Angle of Attack.  Notice turbulence starts to form before the wing is fully stalled on a "clean" wing, resulting a peak Lift/Drag  of around 6 degrees.  By energizing the air flow and keeping it attached, more lift can be created at higher AOA as seen in Graph A.

However, anything that cannot be retracted will carry a drag penalty at optimum L/D, but, as with many larger radius leading edges, Vortex Generators, or VGs, can make the L/D curve much smoother and predictable rather than a sharp break from a very narrow peak.

VGs have found application in elevators, but a flap beyond a given angle of deflection is actually more useful stalled and draggy.  Lower degrees of flap deflection, along with slats, serve to increase camber of the wing to create more lift at lower speeds, also with a drag penalty compared with "clean".

Note the airfoil used in this study is cambered.  It starts to generate lift a -5 degrees AOA, and drag with VGs is actually greater than "clean" at lower AOA typically found in cruise (Graph B), with little difference in lift produced.


What is the flap extension schedule on approach for an airliner?

(Boeing 777 manual.)

Substitute altitudes with position to runway. Near an airport an airliner usually flies at around 200 KIAS, this is when you select flaps 1.

Subsequent flap settings are also combined with selecting a lower speed as shown above. The speed tape makes it easy. Flaps 5 should be down by the final intercept path to the localizer or before turning base. Flaps 20 when established on the localizer. Then comes gear down and flaps 30 before the glide-slope is captured.

Initially you wrote PMDG, I recommend check their manuals, they are usually very informative.

For normal procedures on a Boeing 737, the flap settings 2, 10, and 25 are usually also skipped. So it's 1, 5, 15, and 30/40. Non-normal procedures differ.


If I'm not mistaken, a spat is a fairing for the gear to make it more aerodynamic.

  An aircraft wheel fairing, commonly called a wheel pant or spat or, by
  some manufacturers, a speed fairing. Wikipedia


Who is responsible for providing ATC in a TMA?

It depends.

Air traffic control service in a TMA can be provided by either an air traffic control tower (TWR), an approach control unit (APP), or an area control unit (ACC) - or any combination of those.

A TMA is typically considered to be APP airspace, but there is no rule preventing a TWR or ACC from covering a TMA, and there are many examples of this happening throughout the world.

The typical division, if you need a simple answer, is:

TWR provides service in a control zone (CTR)
APP provides service in a TMA
ACC provides service in a control area (CTA)


What appears on EGT Gauge if the mixture is rich or lean?

The exact number on an EGT gauge is usually meaningless: The Alcor EGT gauge you'll find on many aircraft has no temperature markings on it - just 25-degree divisions, and a yellow "reference pointer" which the pilot sets to the maximum observed EGT:

The notable exception to this is turbocharged engines which have a Turbine Inlet Temperature (TIT) limit to protect the turbocharger. For engines with exhaust gas / turbine inlet temperature limits these limits will be specified in the aircraft's Pilot Operating Handbook, and usually marked with green/yellow/red arcs on the relevant gauges.

Exhaust Gas Temperature (EGT) provides pilots a way of monitoring the fuel/air mixture in the engine. It uses the stoichiometric mixture (where Fuel and Air are perfectly balanced so that there is no unburned fuel and no unburned oxygen at the end of the combustion event) as a reference: At this mixture the EGT is at its hottest ("Peak EGT"). Making the mixture richer or leaner will reduce the EGT, and all other mixture settings are described in terms of "Degrees Rich of Peak" or "Degrees Lean of Peak".

Refer to the handy chart from Lycoming below for the remainder of this discussion:

EGT and Mixture

When we talk about mixture in piston aircraft engines we're generally interested in one of two things: Best Economy - getting the most power from the engine for the least amount of fuel, or Best Power - Getting the most power from the engine regardless of fuel burn.  We're also interested in something called Detonation Margin, which in simple terms means "how likely is this mixture to explode rather than burn nicely?"

As you can see on the Lycoming chart above the EGT provides us a way of finding those mixtures.

Best Economy Mixture

The "Best Economy" range begins at peak EGT, and continues on the lean side until the engine won't run smoothly anymore (usually the limit is about 100-150 degrees Lean of Peak).
Operating the engine at Best Economy mixture provides the most power for the least amount of fuel, and thus the longest endurance. It comes at the cost of a reduced detonation margin on the fuel/air mixture - operating at high power settings with a best economy mixture increases the chance of detonation.

  Most aircraft/engine manufacturers recommend Best Economy mixture for power settings below 75%, in part to reduce the risk of detonation.

The Red Box - Where you don't want to run your engine.

The area of the chart from peak EGT to about 100 degrees Rich of Peak is often referred to as "The Red Box" -- in this range the fuel/air mixture has a low detonation margin, and the combustion event is producing the most internal stress on the engine components (cylinders, pistons).
As you can see from the Lycoming chart the Cylinder Head Temperature (CHT) peaks in this range, and there is a risk of exceeding the CHT limits and seriously damaging your engine by operating in this range for extended periods of time, particularly at high power settings.

Best Power Mixture

From approximately 100 degrees Rich of Peak to 200 degrees Rich of Peak is the "best power" range - in this mixture range you can safely run the engine at high power settings (from 75% of rated power to full rated power) with limited risk of detonation. The engine is producing the most power it can in this range, which is useful if you need to climb over an obstacle in your flight path.
For simple aircraft with fixed-pitch propellers the "Best Power" mixture can also be found by adjusting the mixture to obtain maximum RPM for a given throttle setting.

  Operating in the "Best Power" range is not without risks - in particular, detonation is still possible at high power settings. The same Lycoming manual that I pulled the chart above from advises monitoring CHTs when using Best Power mixture settings.

Less Interesting Mixtures

There are two ranges on the chart I did not discuss above - they are what I call the "Less Interesting Mixures"

Leaner than Best Economy

As you continue to lean the engine past the "Best Economy" range you will notice a sharp drop-off in power. This drop is so precipitous that you will no longer be saving fuel as you leave the Best Economy range: You will be burning more fuel per unit of horsepower produced than you were in the economy range.
Eventually the engine will run rough as the mixture becomes too lean to burn, and at the very extreme end the engine will quit, starved of fuel.

Richer than Best Power

Mixtures richer than Best Power don't produce the same precipitous drop in horsepower, but they consume substantially more fuel per unit of horsepower produced. They also have other negative side effects, like producing black sooty exhaust that will get all over the belly of the aircraft.
As the mixture gets richer it will eventually become too rich to burn, and the engine will begin to run rough as it did being leaned. At the far extreme the engine will become flooded, and cease to run.

Recommended Reading / Viewing

Your engine manufacturer's operating instructions
Mixture Magic (John Deakin)
EGT, CHT, and Leaning (Mike Busch)
Leaning Basics (EAA/Mike Busch) (video)
Leaning: The Advanced Class (EAA/Mike Busch) (video)


Is this Part 23 Final Rule document the final regulation and what are the main improvements?

The document itself is final, but it isn't the same thing as the actual regulations.

The same thing happened with the recent part 107 UAV regulations: the final rule document came first, then the regulations were published later. That means, at some point soon (?) the part 23 regulations will be updated to include the final rules you found, but I have no idea exactly when that will happen. The Part 23 final rule itself says:

  DATES: Effective [INSERT DATE 8 MONTHS AFTER DATE OF PUBLICATION IN
  THE FEDERAL REGISTER].

AOPA has a good explanation of what the rule changes will mean.


What physical tests are involved with verifying a wing spar is suitably constructed for a homebuilt aircraft, such as the piper cub kit from wicks?

For a homebuilt a static load test is required. Whereas a full certification would require a loading to 1.5 the maximum load, this factor is reduced for experimental aircraft to 1.0. But performed it must be nonetheless.

For the test the aircraft is propped up upside down and sandbags (or water bottles) are placed on the wing until the calculated load is reached.

Structural test of the Electra One (picture source)


Is it recommended to have an ADS-B transponder in ALT mode on the ground?

Yes, it's in the the AIM 4-1-20:

  3. Transponder and ADS-B operations on the
  ground. Civil and military aircraft should operate with the transponder in
  the altitude reporting mode (consult the aircraft’s flight manual to
  determine the specific transponder position to enable altitude
  reporting) and ADS-B Out transmissions enabled (if equipped) at all
  airports, any time the aircraft is positioned on any portion of an
  airport movement area. This includes all defined taxiways and runways.


What is the meaning of "pass well clear" in the ICAO right of way rules?

This is probably one of those rules which is deliberately a bit open to interpretation. For example, a glider pilot will be happy to pass under another glider when hill soaring at 40 knots much, much closer than they would be if cruising at 100 knots! Other pilots will probably use standard separation minima, for example 500 feet might be acceptable in the powered circuit but 1000 feet is allowed in certain airways.

SKYbrary suggests that "well clear" means 500 feet, but again points out that it might not be sufficient when using TCAS.

The implication is of course intended. If one is "well clear" by 20,000 feet there is no need to take avoiding action!


How can I find aircraft and airline listing data for planespotting?

You can find much of this sort of information at http://www.airfleets.net

For example, searching for British Airways lists their fleet, and clicking the number of active for a model (eg A318) will list the tail number and other interesting information. From there you can click a specific airplane for all the information along with a picture.


Why does the B-52 take off without rotating?

The reason was to give the bombs the place close to the center of gravity.

Wing sweep (for high cruise Mach numbers) in combination with a high aspect ratio of the wing (for low induced drag) made it impossible to place the landing gear in the wing, so it had to be integrated into the fuselage. The main landing gear normally needs to be close to the center of gravity (slightly behind for a tricycle gear, slightly ahead for a taildragger), but this space was needed for the massive bomb bay. Since the bombs will be dropped somewhere along a bombing mission, dropping them should not upset the balance of the aircraft, so no compromise was possible.

B-52 cutaway drawing showing the two bomb bays in the center of the fuselage (picture source)

This problem existed already during the development of the 6-engined B-47 a few years before. In both designs, two pairs of landing gears were chosen, one pair ahead and one pair aft of the bomb bay, and the aircraft lost its ability to rotate for takeoff. Due to the powerful fowler flaps the attitude in cruise and at slow speed could be made identical. The downside is more drag during the take-off run, since the wing produces more lift, but this could be tolerated in a strategic bomber with air refueling capabilities.

B-47 on approach with gear down and drag chute deployed (picture source). Note the outriggers between the inner pair of engines - those were needed to keep the aircraft level on the ground.

B-52 in flight with gear down (picture source). Here the forward and aft gear of the B-47 have been replaced by pairs of gears to distribute the load over eight wheels and the outriggers are positioned outside of the outer engine pair, but the general gear configuration is fairly similar.

The Russian design bureau Myasishchyev found a different solution for their M-50 supersonic bomber in the mid-50s. They also had to put the bomb bay into the center fuselage and the main gear had to be placed so far aft that the M-50 could not be rotated the usual way with the elevator. To solve the problem, the engineers devised what they called the "galloping bicycle". When the aircraft reached 300 km/h, the forward gear rapidly extended to rotate it to 10°.

Myasishchyev M-50 with extended front gear strut (picture source). The two open doors under the cockpit were for the pilot and navigator: Their downward-ejecting seats would be lowered on cables for the crew to be strapped in at ground level, then winching themselves into place.


What is needed to take off in CAT IIIb weather and how is it done?

Under the US FARs (at least part 91) nothing special is required to take off in CAT IIIb weather besides an operational (and IFR-legal) aircraft and pilot. As mentioned elsewhere you can legally make that Zero/Zero takeoff where you can't even see the runway under your nose.

It should go without saying that doing so would be incredibly stupid (we (and the FAA) have said so anyway), but from a technical standpoint there's nothing preventing the operation except the knowledge that you might run off the side of the runway into a ditch and bang up your aircraft and passengers.

In terms of what would be required to make the takeoff safely, without running off the side of the runway into a ditch, I'd posit that you would need the same capabilities as you'd need to make the CAT IIIb landing safely: Aircraft systems that let you reliably track down the centerline for takeoff (using the ILS or something of equivalent accuracy for guidance, and runway centerline lights).

You would also need a reliable way to get from the gate to the runway, so taxiway centerline lights & stop bar lights are a must, and probably ASDE-X or its functional equivalent with a controller monitoring it to help ensure you don't taxi into another aircraft.

All of the above is predicated on, among other things, being able to see the lights I mentioned. The "takeoff guidance system" mentioned elsewhere adds synthetic vision into the mix which further enhances safety (and in the airline world allows takeoffs down to 300ft RVR). From what I can glean from the Rockwell-Collins marketing material their HGS seems to be able to provide "follow the green dots" taxi guidance (and presumably runway centerline guidance for the takeoff roll as well), providing redundancy for the lights I described above to help the pilot ensure the aircraft is going where they want it to.


What is the average angle planes wings they need to fly?

The angle of attack airplanes fly at while cruising is called the optimum angle of attack (around 4 degrees) which meets the max.(L/D).


How often is communication lost with aircraft?

According to this FAA paper, Table 3, ASRS reports were analyzed for 16 months between 1978 and 1979. This included 553 incidents where the recipient was not monitoring, which seems to be the closest category to loss of communications. This equates to a little more than 1 incident a day. Note that this only includes incidents that were reported, and air traffic has increased since then.

This report contains info from ICAO in in Europe. The focus is on the security issues from unresponsive aircraft. In just the northern region, there were 230 flights over just 6 months in the beginning of 2004. This number inclues airlines, business jets, and military transports. This frequency is a little higher than the previous report, but is more recent and probably includes less flights.

Other reports like this one don't include a time frame for the reports analyzed, but look at other factors involved. For example, pilots with fewer hours and GA pilots are more likely to be involved in such an incident. The average duration of these incidents was 7.6 minutes.

This page also has some good information about this type of incident, including a list of some of the many possible reasons for lost communications and excerpts from some of the reports.


Early models of Supermarine Spitfire (prior to the 175th production aircraft) had no hydraulic gear extension system, according to Wikipedia:

  At the same time the manual hand-pump for operating the undercarriage
  was replaced by a hydraulic system driven by a pump mounted in the
  engine bay

Source

The movie could show the normal extension of the undercarriage, using a lever, but a lost engine would not impact the operation.

After the 175th aircraft, the gear was hydraulics powered, so without engine running, the pressure could be insufficient. The design included an emergency extension using a $\small \textrm {CO}_2$ cylinder:

Source: 1940 Spitfire Manual

The system is visible on this image (black bottle with red handle "Emergency Only"):

Source

The hydraulic gear control box is at the center.


Are there regulations on building homes at the end of a runway?

The FAA has regulations on the maximum height of obstacles around a runway (page 22):

  The runway Obstacle free zone (OFZ) is a defined volume of airspace centered above the runway airspace above a surface whose elevation at any point is the same as the elevation of the nearest point on the runway centerline. The runway OFZ extends 200 feet (60 m) beyond each end of the runway.

...

  The inner-approach OFZ is a defined volume of airspace centered on the approach area. ... Its width is the same as the runway OFZ and rises at a slope of 50 (horizontal) to 1 (vertical) from its beginning.


Can endplates be used to reduce chord length by up to 14%?

It would be possible to do as you suggest.

However the short-chord wing would have to be either thinner and therefore heavier, or less streamlined and therefore less efficient causing higher form drag. Both effects increase induced drag.

The endplate would need to be roughly square in proportion, which would add drag of its own. Also its mass and side area would complicate the aircraft behaviour.

It is generally better to add a small winglet rather than a big flat plate and use it to reduce the wing tip vortex. But even there, a bit extra wing span with suitable washout is just as good.


Are there rules regarding the accuracy of a pilot's delay announcement?

No precise rules that come to mind offhand, but:

these days, the passengers often get text messages with delay info, and if I'm saying "3 hours" as the text comes in saying "30 minutes", that is not good
people who might wait out a 30 minute delay might decide to rebook or cancel their flight for a 3 hour delay
if there are passengers making connections to other flights at the destination, the difference to them between 30 minutes delay and 3 hours is immense, and they can get upset, call the airline reservations people, want off the aircraft to talk to customer service, etc
an actual delay of 3 hours is reason to deplane everybody, now (in most cases); for 30 minutes, not so much. That process & subsequently re-boarding everyone takes time, and it's no fun for anybody.
play the "oh, wait, now the delay is xxxx" card too often, and you look like you don't know what you're doing.

My gameplan is to give the passengers the honest answer. Sometimes, this is along the lines of, "may be a quick fix, like 15 minutes, or it may be a lengthy delay, in the ballpark of 2-3 hours. We expect to know which situation we have in about 15 minutes or so, and we'll let you know when we get the word from Maintenance." I think people appreciate it when you give them the straight scoop, including the times when the crystal ball is cloudy.


What materials are plane windows made of?

Generally aircraft windows are made of what we colloquially call "plexiglass" of some kind (Lexan polycarbonate is common in light General Aviation aircraft, acrylic plastics are also used).  This material is light, relatively strong (not shatter-proof, but it'll take a moderate beating) and has decent optical properties.
Its major drawback is "crazing" -- hairline cracks on the surface of the material that form over time from dirt, stress, temperature, UV exposure, and the like.

Bonus answer: The little hole serves a couple of purposes, but the biggie is pressure relief/equalization. This gets discussed over on airliners.net a lot and they've covered it pretty thoroughly.

Basically the hole ensures that the cabin pressure is pushing against the outer (primary, usually thicker) sheet of plexiglass, which is plug-wedged into the fuselage structure and can't go anywhere.
Should the outer pane be damaged the hole will also theoretically bleed cabin pressure off at a controlled rate - though how successful that equalization is would depend on your altitude (and thus the pressure differential between the cabin and the outside air) and the degree of damage to the outer pane.


Is there any aircraft that cruises in the transonic regime?

If we define the critical Mach number as "the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound, but does not exceed it," then yes, many aircraft cruise above this speed. Any modern jet airliner has some supersonic flow over parts of the wing and fuselage at cruise, placing it squarely in the transonic range. This video and its description provide a great visualization and explanation of the associated phenomena.

It should be noted, however, that there is not necessarily a large increase in drag upon reaching the critical Mach number. More useful in the transonic range is the drag-divergence Mach number, which is always greater than the critical Mach number. Supercritical airfoils are designed specifically to increase the drag-divergence Mach number, and are fitted to all modern jetliners.


What crosstrack should I have during a holding pattern?

If you follow the holding guidelines you will never leave the protected area. This includes performing an appropriate entry, applying correct wind correction, and flying the correct leg length.

ATC expects you to slow to holding speed no later than 3 mins before arriving at the holding fix for planning purposes, and generally doesn't expect you to use the entire protected area. However, the entire area is protected, so you could use it if you wish.


Why RNAV SIDs and STARs are RNAV 1 instead of RNP 1?

First of all, an RNP 1 procedure requires a GPS/ GNSS. And as you have said, it requires an inbuilt navigation monitoring and an alerting system. On the other hand, an RNAV 1 procedure does not. In RNAV 1 you can get navigational aid from the IRS/ VOR/ DME or IRS/ DME/ DME.
The SIDs and STARs can either be RNAV 1 or RNP 1. RNAV 1 is the system introduced at the start of performance based navigation to cater for smaller air spaces (terminal area procedures) and it is a step towards changing over to RNP 1. Many countries these days require an aircraft with RNP 1 capability to fly their SIDs and STARs. They sometimes tend to name it unambiguously on the chart. Like a chart might state, RNAV 1 and then state that you require a GNSS. This essentially makes the procedure an RNP 1 procedure. Others state specifically that you need to be RNP 1 complaint. This means that you need to have a GPS and a monitoring and alerting system. This is mainly seen in China, where most of the airports require the aircraft to be able to fly RNP 1 procedures so that they can pack airplanes together, with minimal ATS surveillance. This is done to accommodate the ever increasing air traffic in the region.
It has been quite a while, since I have not been to Wuhan, China for obvious reasons. Wuhan airport is one those example airports which allow only aircraft that can fly RNP 1 for their SIDs and STARs.

I think the advantage of keeping the charts and procedures RNAV is that it allows operation of older aircraft, which does not comply with RNP operations. This is I believe quite important in a place like the United States where airlines still tend to operate older aircraft and has a big general aviation sector. In other places, airlines tend to have newer aircraft, which easily fits into the current navigation standards. This makes it easy for the regulators to change their procedures to RNP.
For the question regarding losing RAIM (Receiver autonomous integrity monitoring). If you lose RAIM, you probably cannot do a GPS/ RNAV (GNSS)/ RNP approach (same type of approach, just different names). But the aircraft can still be used for RNAV navigation, as RNAV does not require the monitoring and alerting.


How should the Swiss international airlines flight 850 METAR reports be interpreted?

Can someone clarify?

I can try to clarify the METAR report:

From the Wikipedia source link on METAR:

EDDT:  METAR for Tegel Airport
VRB01KT: Wind variable at 1 knot (1.9 km/h)
9999: visibility in excess of 10 kilometres (5.4 nmi)
FEW040CB: few clouds at 4000 ft. including cumulonimbus
SCT120:  scattered clouds at 12000 ft
BKN260:  broken clouds at 26000 ft
29/17: temperature 29 degrees Celsius, dew point 17 degrees Celsius
Q1002: current altimeter setting (in QNH) is 1002 hPa
A2959 0998 2947: current altimeter setting 29.59 in.Hg, falling to 998 HPa, 29.47 in.Hg.
TEMPO: Temporarily

27025G55KT: Temporarily winds from 270° at 25 knots (46 km/h), gusting to 55 knots (102 km/h)
2000 +TSRA: visibility 2000 meters (1.1 nmi)
+TSRA: heavy thunderstorm and rain
BKN009: broken clouds at 900 ft
BKN015CB: broken clouds at 1500 ft including cumulonimbus

COMMENTS: OCNL LTNG AND CB SW OF STN: Occasional lightning and cumulonimbus clouds south west of the station

  Why are there multiple mentions of the same types of clouds?

The TEMPO group is used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time (occasional), and are expected to occur during less than half the time period.

  Are they talking about different height/direction?

The Sky Condition (i.e.:FEW040CB SCT120 BKN260 ) reports the sky coverage and is given for different height, the following three-digit height is given in hundreds of feet.

For further clarification of METAR convention I find this useful!

  My understanding is that NOSIG means the weather is not expected to significantly change in the next two hours.

Correct, NOSIG stands for NO SIGnificant change, doesn't mean that the weather will not change!


Are seaplanes allowed to taxi in residential areas?

A sea plane was just going around it. It was very loud and got like 10 feet from the shore. It's just going in circles and won't take off and leave.

As has been pointed out in other answers and comments, if the aircraft is taking off or landing, there are no regulations requiring distance from persons or structures, at least that I know of.

What you may be witnessing is an attempt to takeoff in less than optimal conditions. For example, if there is no wind and the surface of the water has no wave action, it can be very difficult to break away from the water sufficiently to get the aircraft "up on the step", in other words to get it going fast enough that it can plane along the front part of the floats (or the hull). Once the floats are "planing" on the water, with the lesser drag than if they are fully in the water, the aircraft may then be able to accelerate to takeoff speed.

The usual procedure if you're having trouble taking off from a wave-less water surface (often called glassy water), is to run back and forth at a high power setting with as much speed as you can get to generate waves. Then, at some point hopefully, as you run back across waves you've previously generated you'll be able to break free of the water because there's less drag running across waves, even small ones (ripples even) than glassy water.

I had to employ that procedure a few times back when I was flying floats, and I remember one instance when it took at least a half hour before I managed to get airborne.

  Are seaplanes allowed to fly in residential areas?

I can't speak to current practices and regulations as I retired in 1999. However, back in the 1970s and 1980s when I was flying floats, we often operated in residential areas. For example, go to Google Earth and bring up Eugene, Oregon. Look at the area on the Willamette River immediately adjacent to downtown Eugene. You'll notice two bridges. We often operated alongside residental areas upstream and downstream of the bridges. We also operated between the bridges. Depending on conditions that sometimes meant flying under one of them, not an uncommon practice for seaplanes, and perfectly legal, at least back then.

If you don't have Google Earth, you can use the Google Earth browser version or see it on Google Maps.


Are the Gulfstream III's ailerons controlled by hydraulically boosted cables?

Yes, the flight control surfaces on the Gulf Stream III are moved by cables with hydraulic assistance.

From a study guide for the type.

  The flight controls on the G III are cable driven with hydraulic boost..  They are powered by both the "Combined" and "Flight" hydraulic systems.  Each of the systems provides 1500 psi to the flight control servo actuators.  When the landing gear or flaps are extended, the combined system pressure increases to 3,000 psi.  If one system fails, the remaining system pressure increases to 3000 psi.  Failure of one hydraulic system therefore, does not result in a loss of control effectiveness.

As to whether a mechanic could interfere with the controls, of course.  But for what purpose?  I am not sure that I understand what you mean by "tamper" but I assume that you mean sabotage. If so, then there are multiple ways to do this but I see no point in speculating as to what someone might do or why.


Why was there no issue with the Tu-144 flying above land?

The actual 'legal' reasons have already been mentioned. However, there was a bit more to it.

Tu-144 was meant to fly over land from the beginning; there was no way around it, unlike Concorde. So it was designed to fly higher. In particular, Tu-144 had about 20% lower wing loading and 20% higher thrust-to-weight ratio (at MTOW) than Concorde. (The reality was a bit more complicated; for example, Concorde was limited to FL600 again for 'legal' reasons, due to certification of the pressurisation system AFAIK).
Soviet citizens, apart from not being asked their opinion, were quite used to sonic booms from military aircraft. In many places of the country, they wouldn't even raise an eyebrow. In the Urals where I grew up, I heard them almost daily.


Why do pilots say "clear of the active" at non-towered airports?

Honestly? It's probably because they heard someone else do it, and thought it sounded cool (or otherwise just got it stuck in their head).

You're 100% right - saying the runway name is, if slightly longer, certainly a bit more informative. It's the kind of thing that can help arriving pilots know which runway is in use, keeping later radio clutter ("Um, uhh, Jeffco Traffic, um, say runway in use?") to a minimum for pilots already on frequency. Even a 'one runway airport' still has two runways (09/27, for example), and it's nice to know which one you should set up for when winds are light.

The preferred terminology is more like "Jeffco Traffic, 3AC, clear 29".


Why do planes always land on rear wheels instead of the nose wheels?

Aircraft land on the main wheels. For aircraft with nose wheel it is the back ones, but for aircraft with tail wheel (also called “tail-draggers”) it is the front ones. In either case the main wheels are very close to centre of gravity and carry most of the aircraft's weight, the nose or tail wheel only carries a small fraction of it.

The aircraft must land on wheels that are close to the centre of gravity (longitudinally). If they were not, the force on the wheels would create a moment that would violently pitch the aircraft. Actually, tail-draggers tend to bounce on landing a bit because there still is some moment left and in case of tail-draggers it pitches the aircraft up.

Early planes were almost all tail-draggers, because that layout is more robust, handles unpaved runways better and has less drag when the gear is fixed. It however provides poor directional control especially once the tail lifts off the ground during take-off roll. Later most designs started to use nose-wheel, because it provides better directional control, is directionally stable, makes the floor level when the aircraft is standing so loading is easier and visibility during taxi is much better and with invention of retractable landing gear the drag didn't matter any more.


How do insects decrease aircraft performance?

You're right, insects are very small, so they influence things which happen on their scale. The one important phenomenon on an airliner which has the scale of insects is the boundary layer, the sheet of air around all wetted surfaces where air speed changes from zero (relative to the plane) to the speed it has at some distance. This is called the boundary layer. Its thickness changes from zero at the stagnation point to several centimeters at the end of a long fuselage.

What does the boundary layer look like?

At the leading edge, the boundary layer starts with a thickness of zero. Now friction with the wing will cause some air molecules to be slowed down, and soon you get a sheet of air in which the molecules closest to the aircraft's skin will move with the skin, and the more you move away from the skin, the less they are slowed down. Initially, the layers of air within the boundary layer show no cross movement of molecules. Compare it with a multi-lane road with bumper-to-bumper traffic where no car changes lanes. Since all molecules move along their layer of air, this is called laminar flow (lat. lamina = layer).

At some point downstream oscillations will develop, and once they become unstable, molecules will move between the layers of air. Now you have faster ones from more distant layers moving closer to the skin and kicking the slow ones there ahead, and slower ones from close to the skin moving away, slowing down the more distant layers. Now the cars in your multi-lane road cross lanes, and the result is that all lanes but the rightmost one will move at similar speed. Since the cross-flow is the result of turbulence, this boundary layer is called turbulent.

Speed profiles of laminar (left) and turbulent (right) boundary layers. Image source.

Consequences for drag

The cross flow causes the turbulent boundary layer to have a much steeper speed gradient at the aircraft skin, causing much more friction drag. At the same time, more energy is taken from the flow due to friction, so the whole boundary layer becomes thicker. If you look at the local friction drag, the parameter plots made possible by XFOIL are quite illuminating.

Friction drag over chord for an E502mod airfoil at 3° AoA. Blue: Top surface, Red: Bottom surface.

The plot shows the friction over chord for an airfoil at 3° angle of attack. All flow is attached (save for one small separation bubble on the bottom near the transition point). Can you spot the transition points from laminar to turbulent flow? Yes, it's where the friction drag jumps up and stays annoyingly high downstream. Note that the flow around an airliner's wing happens at a much higher Reynolds Number, so the transition points are closer to the leading edge than in the plot above. I chose the low Reynolds Number in the plot above because it shows the phenomenon more clearly.

But you see also a friction spike at the nose! This is caused by the very small thickness of the young boundary layer. Even though it is laminar, it shows a high friction contribution simply because it is still very thin. Now imagine you have both effects, a thin boundary layer and the bigger friction of a turbulent boundary layer, added together. This is what bugs at the leading edge of the wing will give you! They make the wing's surface rough and drive up friction losses due to an early transition of the boundary layer into turbulent flow.

Consequences for maximum lift

But there is also a second effect: The longer the boundary layer develops, the more the flow loses the ability to slow down and increase pressure towards the trailing edge. A flow's energy is either speed or pressure, but if the energy of the flow is sapped by friction, none of both is left when needed to negotiate the last half of the wing's shape. The flow will separate earlier if it had been turbulent from the beginning, and the wing will stall at a lower angle of attack. This is the second negative consequence of bugs on a wing. It can be mitigated by careful airfoil design, but then this airfoil will show lower bug-free performance.

Glider pilots know this very well, especially those who flew planes which used the Wortmann FX 67-170 airfoil. It had excellent L/D without bugs, but both rain and bugs converted the plane to something resembling a brick. I once flew a Janus B into a shower, and minimum speed increased from 80 km/h to 110 km/h. A few seconds of flying at higher speed cleaned the wing, but then it was time to land, because I had lost so much altitude.


How much water is carried for jet engine water injection?

This paper here gives a good overview of water injection.

It suggests for injecting water into the compressor, a 300 gallon tank is necessary, for a 2.2% water to core air flow ratio (the historical norm), for injection from take-off to top of climb.

For injecting into the combustor, it suggests a 135 gallon tank, for a 0.5:1 water to fuel ratio, again for injection from take-off to top of climb.

For both of these scenarios, the tank water flow rate was designed to achieve a 50% NOx reduction. The paper gives other water quantities required to acheive different goals (eg different NOx reductions and different turbine temperature reductions).

I don't think the paper indicates how long it takes to get to top-of-climb. I assume these are US gallons, as its a US paper.


Why do pilots sample the fuel before a flight?

On the first flight of the day, after every refueling, and if you have flown through precipitation or the plane is left in the rain, you check the fuel for water and to make sure you have the right kind of fuel. Since water is heavier than fuel, if there is just a little bit of water in the fuel it could cause the engine to stop. You can’t pull over to the side of the road like you can in a car, so you need to immediately deal with the problem. The most likely place for this to occur is on takeoff. If you think fast and switch tanks, you might get lucky and only have water in one tank so you can continue your takeoff. If not, you may need to find a place to land.

In 17 years of flying, I have only found water in the fuel once, and it wasn’t even my airplane. But since it was on Catalina Island, a stopped engine would not have been pretty.

The other reason to check the fuel is that airplanes designed for 100LL do not burn Jet Fuel. Jet fuel is denser than 100LL so it will sink to the bottom of the tank. It is straw colored and somewhat greasy, so you can tell if your plane has accidentally been filled with it, but you really have to be paying attention. It would be easy to miss if you just topped off. There have been incidents when twin-engine planes have mistakenly been filled with Jet A and have either crashed or required expensive fuel system cleaning. Mike Busch's article describes his experiences. After the misfueling of a Cessna 421s, someone did a test to see how easy it is to identify a combination of Jet A and Avgas. It’s fairly hard using standard pre-flight practices. That’s why many people recommend watching the fuel truck if you have a twin-engine plane or one that prominently says “Turbo” on the side.

Many aircraft have rubber bladders to hold the fuel. Most older Cessnas  have them. Water can get trapped in the folds of the bladder and get into the engine later when the fuel is sloshed around.

Even if the fuel source is free of water, a tank that is not full can have water condense in it.

Most autogas has some ethanol in it. Water will dissolve in a gas-ethanol mixture and so a slug of water won’t get into the engine like it will in an aircraft engine.

Contamination is less of an issue and is one that is really hard for a GA pilot to determine. You really can’t tell if the fuel is contaminated with other petroleum products just by looking at it.


What is the most severe engine failure for modern turbofan?

Here are my initial finding so far, and I will add information that I find along the route:
There seems to be two types of engine failures. Tested and untested ones. The ones that the engine are certified for through test are the ones that are likely to happen in the fleet life. And therefore, the engine manufacturer must show that those kinds of failure will not put the life of the passenger at risk. The other are unexpected incident that shouldn't have happened and are certified through numerical analysis.
The most extreme scenario in the tested failure category seems to be the fan blade out. The unbalance created by losing a fan blade creates huge vibrations and breaking torque when the fan rubs against the casing. In addition to that, the compressor is stalled so you have backward flow in the engine and huge ball of fire coming out. (see this video).

To obtain the engine certification, the manufacturer must demonstrate during a dedicated test that all broken blades remain in the engine and that no heavy parts will exit either in direction of the aircraft or fall to the ground.
Sadly, it doesn’t work as expected and recently two CFM56-7B have had FBO event that didn’t end as well as planned.
Southwest Airlines Flight 3472 and 1380.

Now the untested failure options. Two different examples came during my search, rotor disc rupture and engine loss. Both should never happen but cannot be mitigated if they happen and that's why they cannot be certified.
Let’s start with the American Airlines Flight 191, which engine number one was lost during takeoff. Whereas it is not the engine that failed but the fixations, the consequences where tragic.
Secondly the rotor disk rupture. This time it is not the blades (fan turbine or compressor) that fell off but the whole disk retaining them that fails. This seems mostly due to manufacturing defect with crack propagation not detected during maintenance. The kinetic energy of those disk is such that it would require a tank shield to prevent them from escaping from the engine which weight would be horrendous. Sadly, they are more example of those:
Delta Air Lines Flight 1288 (MD-88, the NTSB determined the most probable cause of the accident was a fracture in the left engine's front compressor fan hub)

National Airlines Flight 27 and United Airlines Flight 232 (DC-10 Tail engine fan disk rupture leading to flight control losses, loss of cabin pressure and passenger sucked out)

Qantas Flight 32 (A380, turbine disk disintegrated, causing extensive damage to the nacelle, wing, fuel system, landing gear, flight controls, engine controls, and a fire in a fuel tank that self-extinguished)

Air France 88 (A380, Fan disk failure. The examination determined that the hub failure was caused by a low cycle fatigue cracking process which originated in the part’s subsurface. 21 month later a 150kg piece of the engine was located 4 meters below the snow and was recovered in Greenland.)


Is it possible or has anyone explored the possibility of capturing static electricity for supplying electrical loads on an aircraft?

No, it is not.

To use electricity to do work, you need:

two thigns with stable potential difference,
large amount of charge and
good electrical connection to both terminals

And static electricity does not really give you either:

the amount of static electricity collected depends significantly on atmospheric conditions,
the total charge collected is tiny even though the potential increase can be huge and
one of the terminals is outside air and the electrical connection to it is really poor (if it wasn't, charge couldn't accumulate on the plane).


Why is parking brake set OFF before jacking?

The wheel is removed with the PB depressurized so that the discs are free to float (both rotationally and slightly axially) when the wheel is being slid off, to prevent any potential binding of the disc projections where they engage the slots in the bore of the wheel as the wheel is pulled out. If the discs are locked in place by brake engagement, any off-axis movement of the wheel unit as it's being slid off could jam it on the discs, making it really hard to pull off.

When the procedure is started, the airplane is chocked at the other gears, so the parking brake is already made redundant at this point.  As a former aviation technical writer in another life (not Airbus), I would say it was done that way for work flow purposes (getting all the cockpit related precautions out of the way before you start the procedure) because you don't need the PB on once chocked, and you're going to have to release it anyway, so it's done during the preparation steps prior to the actual jacking.


Does Airforce one carry missiles to protect itself and its passengers?

Near as is know outside of a security clearance the answer is no, a Boeing VC-25 does not carry missiles or offensive weaponry.  During times of crisis, VC-25s are often escorted by armed jet fighters which can attack potential threats to the VC-25 if need be.


Why do some Air Forces not allow Color Blind Pilots?

In fact, most militaries don't take colorblind people into flight school.

Colorblindness can be a serious problem for a pilot, because in the interest of cost and/or simplicity, not all indicators in an aircraft cockpit are colorblind-accessible. It's really cheap to use a two-way red/green LED as a status indicator (and by quickly alternating the current through the LED you get amber); it's much more expensive in electro-mechanical systems to combine text and color so that the status can be deciphered by someone who is red-green colorblind. It becomes easier again in a glass cockpit, but that increases cost and there are still concerns like screen resolution to consider when designing text-and-color displays. While it's in the general interest of aviation manufacturers to design certain avionics with as many overlapping visual cues as possible, it's not always feasible to specifically design towards colorblind accessibility in every circumstance.

Here is a set of spectra simulating how various forms of colorblindness would change a person's perception of the normal color set:

Protanopia and deuteranopia are various forms of red-green colorblindness, the most common form of dichromia (protanopia is a deficiency in red cells, deuteranopia a deficiency in green; the results are similar because red and green are close in wavelength). Tritanopia is commonly called blue-yellow colorblindness and is less common, with full colorblindness (monochromia) being very rare.

From this chart, we can deduce the following basic difficulties for a red-green colorblind person attempting to operate a plane:

Red on brown, or any dark color, would have no contrast. That would make reading (and setting) this Cessna radio stack nearly impossible:

... as well as decreasing the contrast of red lines on high-elevation sectionals (like Charlie/Echo space boundaries, non-towered airports, NDB frequencies etc):

Green and yellow are practically indistinguishable. That would make discerning the borders of inhabited low-lying areas on sectionals difficult:

... as well as making the color-coding of this airspeed gauge much less useful at a glance:

Blue and magenta are indistinguishable, as are cyan and white. That makes your GPS useless over water; where's the magenta line?

While you could probably get around most of these difficulties (buy a nav stack with blue LED displays, trace the borders of your sectional charts in something, configure the GPS to give you a white line, etc etc) these are all images that people with full color vision would be able to discern at a glance, which in an emergency situation is often a life-or-death advantage.

That point is especially true for military pilots, who are typically subject to more rigorous medical screening and training including very high requirements for visual acuity (often better than 20/20 uncorrected vision). If you can't see extremely well in a combat situation, you will either fail to spot an enemy until he has gained a significant advantage over you, or you will fire on friendly forces; either way, you're a liability. Coupled with the fact that everyone and their brother grew up dreaming of being a fighter pilot, flight schools get to be picky. Therefore, military aircraft cockpits are typically designed with the assumption of full color spectrum perception, because the only people who will ever be in them will be able to tell red from green, blue from yellow.

Consider, just as one example, a hypothetical conflict in the Middle East involving the Turks and Iranians, where NATO and thus the USAF is also involved. Both of these countries still operate variants of the F-4 Phantom. With an ROE requiring visual confirmation of a hostile, if you are in a USAF F-22, in a visual-range tangle with an F-4 whose IFF is inconclusive (either non-functioning or malfunctioning) and you can't tell the difference between these two rondels...

... you are screwed. The fact the Phantom is maneuvering against you is what any pilot would do when approached by an aggressor aircraft; a Turkish pilot isn't just going to sit there and be shot down by friendly fire, he'll engage defensive, so you can either shoot and risk spending the rest of your life in Leavenworth for dereliction of duty, or break engagement, presenting your tailpipe to the other craft and hoping it's not hostile. Fifty-fifty shot either way with a hundred and fifty million dollar plane on the line, not to mention your life. Your first clue it's an Iranian would be a missile launch, and no matter how much more advanced USAF craft are now than in the era of the F-4, an aircraft that has successfully launched a short-range missile at you has you by the wrinkly ones.

In addition, ground lighting systems are often not differentiable either. For instance, there is an important difference between a heliport beacon flashing green-yellow-white versus white-green-red (the one including a red flash is a hospital helipad and off-limits to gen-av traffic even in an emergency), but a red-green colorblind person may well not be able to tell the difference. Runway end lights are either green or red, indicating traffic direction (though there's usually a secondary cue of the approach array lights sequencing toward or away from the runway edge). Similarly, to a person for whom red is indistinguishable from white, the red-over-white glide slope indicator at the end of the runway would be useless (this would typically happen only with full colorblindness). Blue-yellow colorblindness is the other major type of partial colorblindness, and it would cause other problems like decreasing readability of navigation charts (for instance, incorporated land areas are yellow on FAA sectionals, while Victor routes and class B/D airspace borders are different blues) and trouble negotiating taxiways as the blue taxiway lights would look the same as yellow-white indicator lights elsewhere on the tarmac.


gear down during takeoff for extended period of time

It's usually for one of two reasons:

Brake temps are displayed in the cockpit and if the temps were elevated from a lot of, or excessive, brake use during taxiing, the capt may delay retraction until the indications come down, mainly to avoid gear bay overheat indications. This will be more common on airplanes that have more idle thrust than necessary to roll at normal taxi speed, which can cause a tendency to ride the brakes.  CRJ200s, which can get going pretty fast on idle thrust with both engines running, are really bad for this.

Also in winter on a departure from a slushy runway, retraction may be delayed to try to blow off as much slush as possible since once the slush freezes, it can immobilize the wheels, preventing normal spinup on the next landing (if it's still cold at destination).


Why is the front section of the Su-30 not aligned with the longitudinal axis of the body?

This is not necessarily the best way to look at this airframe;  it is better observed in a 3-view to understand this.

Viewed from the side and top, the main fuselage does not curve down but blends into pancake like lifting body which mates with the wings and empennage of the aircraft; the engines then are slung under the fuselage in a linear pylon which blends into the fuselage at the tail the design is beneficial for several reasons.

Fuel capacity: The Flanker family of aircraft all have very long legs and can carry a lot of gas due to this flattened mid section and makes a good solution for the need to carry a lot of fuel.
Aerodynamically clean: the blended wing/body design offers low drag as well as low wing loading, making the aircraft very maneuverable as a consequence of high drag during high alpha flight.
Stores carriage: blended wing/body offer a lot of ordnance hard points (12 to be exact) for carriage of weapons, fuel tanks, sensors, etc.

The forward action of the fuselage is based upon the the SU-27UB airframe with an aft crew station raised in order to better facilitate flight instruction in the airplane this required raising this section of the fuselage.  The nose and radome appear to droop down but are laid out that way to increase the real estate for a large radar antenna in the nose radome for increased detection ranges.

Like most East Block war machines, the SU-30 is brutally functional, refined only where needed and passed up for utility elsewhere.  While it may appear to 'curve' the fuselage is essentially straight and the engines aligned with the COG.


What engine power setting is used during cruise?

At first, I was tempted to close the question as a duplicate, but then I could not find one that would address the point directly. But there are many questions and answers on this site which allow one to cobble together the answer:

Why are many jet aircraft designed to cruise around FL350-370?
Why has the maximum service ceiling of Boeing and Airbus products remained about the same for 30 years?
Why do jet engines get better fuel efficiency at high altitudes?
How much fuel does it take to start/land an aircraft, compared to normal flight?
What is the one-engine-inoperative maximum range flight configuration?

To save you to read through all linked answers, here is the gist of it: Jet engines are run at close to their maximum power during cruise, but their thrust is much less at altitude due to lower air density. Airliners want to fly as high as possible to fly faster for the same drag and to gain efficiency, and their designs are balanced to achieve reasonable take-off distances and good cruise performance at close to maximum thrust.


Why is there an altitude limit if we have an IDG failure on the A320?

Short answer: This is the highest altitude where the APU can deliver 90 kVA at ISA temperature.

Details

In normal conditions, electrical power is delivered by two engine integrated drive generators (IDG), one per engine.

IDG used both on a IAE V2500 and CFM56-5B engines. source

Each IDG is able to deliver 90 kVA, a power which is sufficient to feed all systems in the aircraft. As electrical power is vital, a second source is provided and each source feeds half of the systems, but is ready to take over and feed all systems in case of failure of the counterpart.

When one IDG is off, the auxiliary power unit (APU) is used as a backup for the second source. The APU delivers both hydraulic power and electrical power.

Honeywell 131-9A APU. Source

At ISA temperature and below 33,500 ft, the APU electrical generator has the same 90 kVA generation capability.

Source: FCOM (3.1.49)

After 33,500 the APU efficiency for electric power generation starts decreasing. If the aircraft was above 33,500 ft and the second IDG failed, this would leave the plane with a single generator (the APU) unable to deliver 90 kVA required by all the systems. So the altitude limit in the SOP.


Depends entirely on the drones. If the radar system is known and the drone is designed not to be detected by this particular radar system, then the drone can only be detected in exceptional circumstances. Small size would be one way, but in order to be effective, big is better.

Detection has many aspects, and one of them is how soon detection happens. If all you need is to stay undetected while you approach the target, only the frontal aspect needs to be considered. If, however, you want to stay undetected for the whole mission, the task becomes much, much harder.

The radar systems in operation during the Eighties along the Iron Curtain could already detect single, large birds. Adding computerized signal processing and networking of several radar stations has improved detection performance many times over since then. See this question for more details.


How can this single-prop drone maintain stable (rotating) attitude and position?

You can read all about it in their paper (which actually reads quite nicely)

http://flyingmachinearena.org/wp-content/publications/2016/zhaIEEE16.pdf

First, the parameter space (so, location of propeller, mass, etc) was searched for a relatively stable solution.

Then, stability is achieve through active control, so indeed by varying propeller thrust rapidly. This is done in a few cascaded control loops; so an 'outer loop' that has a position setpoint, which is then translated to a desired attitude. This attitude is then achieved by varying thrust throughout the rotation.


Why is it that T-tails want to climb like on a PA-44? It seems like it always wants to climb

Because of the location of the horizontal stabilizer, it isn't as affected by the power setting. Thus, it's likely that you are trimming to compensate for power reductions when you don't need to. I would make sure you trim well, and ensure you are trimming based on what the airplane needs rather than what you would put in on a Cessna.


What are these openings on the TBD/TBM Avenger?

It's a leading edge slot used to improve low speed handling.

Excerpt from Wikipedia:

  Partial-span slots are usually found only on the outboard portion of
  the wing where they ensure airflow over that portion of the wing will
  remain unstalled at higher angles of attack than the inboard portions
  of the wing. This ensures the wing root stalls first and contributes
  to docile stall behaviour and maintaining aileron control throughout
  the stall.

You'll notice that the slot is directly in front of the ailerons. Since the TBMs landed on aircraft carriers very close to a stall, the slot ensured adequate roll control during approach and landing.


No, it's not a missile, it's a towed target:

Towed targets are used for electronic warfare and gunnery training. The can serve as a radar target or visual target during military exercises.

The 'missile' is on a long cord and can be reeled from the aircraft. The pod that you see here is a MTR-101 reeling system with the capability to drag the target up to 30,000 ft behind the aircraft.

If you are interested in flying these kind of missions, it seems  L3 is looking for a new First Officer for their Learjets.


Why is the pitching moment coefficient of an airplane said to be constant about the aerodynamic centre of an aerofoil?

Because the phrase "aerodynamic center" is defined as meaning "the point about which the pitching moment coefficient is constant."

That's it, that's the entire answer. If I've misunderstood the question, please let me know.


What percentage of airplanes are involved in a crash in their lifetime?

I just ran some numbers based on Wikipedia statistics. I don't know how they define "incident or accident" but hull loss is pretty straightforward. That means it was written off.

Aircraft type
Total made
Incidents/accidents
Hull losses

DC-10
368
55 (14.2%)
32 (8.3%)

L-1011
250
32 (12.8%)
11 (4.4%)

727
1832
336 (18.3%)
118 (6.4%)

737
8725
368 (4.3%)
184 (2.1%)

747
1514
131 (8.6%)
60 (4%)

All of these were introduced in the late 1960's. As you can see, the DC-10, L-1011, and 727, which are mostly retired, have pretty bad numbers. But the aircraft that are still being made and flown have much better stats. I think this is probably due to the fact that air travel gets safer all the time. The planes that had their heyday in the 70's and 80's fared poorly but the longer they continue to be produced, the less likely they are to crash.


Do pilots ever intentionally land a monowheel glider on the main wheel and a wingtip wheel in crosswind conditions?

No.

The lever arm of that glider wing is too long and the ground contact force too hard to control. You risk a tailspin which at touchdown speed might very well include a fractured tailboom.

Glider pilots fly their crosswind approach crabbed and try to keep the wings level. After the flare the ideal landing would include a brief kick on the leeward rudder pedal to align the fuselage with the direction of movement just as the wheel touches the ground, but even a slight sideways movement at the point of contact is no problem. Wing tip contact is avoided at all cost and delayed until the glider has slowed down so the ailerons cannot keep the wings level anymore.

The only exception is when there is no safe landing feasible – say on a rocky slope in the mountains. Then the advice is to sideslip the glider into the ground, hoping that the crashing wing will absorb enough energy to let the pilot survive. But that is a single-point landing and quite different to what you have in mind.

But there is one aircraft that can take off from a two-point (actually, counting the tailwheel, it's three, but two of them are the single main wheel and a wingtip) and that is the Akaflieg München Mü-23 motorglider (picture below, source). Starting from a position 90° to the intended take-off direction and with the wingtip pointing into that direction down on the ground, the pilot opens the throttle and lets the aircraft swing around. By the time the aircraft has completed the 90° course change, the wing is level from the centrifugal force and the speed is high enough to keep it there with the ailerons.


It was originally Royal Air Force slang for altitude in thousands and not a way of pronouncing AGL.

Up in the air, where the angels fly.

https://en.wikipedia.org/wiki/RAF_slang

Angels 10 meant 10,000 feet.  Cherubs were hundreds of feet.


Can light GA aircraft implement fly-by-wire technology?

There are multiple factors here:

The first and main one is of course weight. Fly-By-Wire requires computers and hydraulics to actuate the surfaces in a small plane weight is critical and a FBW system may be the difference between 3 and 4 passengers in total capacity.

The next that comes to mind is certification, I'm not sure exactly how this works but I would think that FBW implementation in a current airframe would require a recertification of sorts. With that being said many GA planes flying out there like the 182, Piper Arrow and other similar things still made today are sporting designs first flown more than 30 years ago. It's a simple matter of, "if it ain't broke don't fix it".

I would think that basic service and maintenance would also become more complex and worst of all more costly. I don't know much about the cost of these systems so I wont comment father than speculation like this.

There is a safety concern in small planes (and I'm sure even bigger planes) if control feedback is not present. This Article outlines some serious concerns with the Cirrus side stick and its lack of feedback (not fly by wire but some of the ideas carry over to the FBW systems that don't have feedback).

A Note on the 172:

The way I understand FBW leads me to think the 172 does NOT have FBW flaps. While they are electronically actuated I consider FBW (and by definition):

  ...flight control computers determine how to move the actuators at each control surface to provide the ordered response

There is no computation done in a 172's flaps to my knowledge, if you move the switch they will move. While the flaps are not directly cable driven I would consider the lack of computer to keep the 172 out of the FBW category but thats just personal opinion.

Also of note, the 172 did not always have electronic flaps - that was a later addition to the aircraft in '65.

A Note On Cost:

Although you note that one must ignore cost in this case you really can't. A FBW system would make a GA plane even more expensive than they are. This is a very real and very limiting factor in aviation. With an unlimited budget you could develop, certify, and regularly fly a FBW small plane that was chock full of gadgets but the FAA approval process is what it is and cost is a very real limit for aircraft makers.


I have a FAA Private VFR SE license based on my foreign license, and added IFR in my home country; how to upgrade the FAA license?

I assume that your FAA private license was issued under 14 CFR 61.75, and that section also includes the requirements for adding instrument privileges:

  (d) Instrument ratings issued. A person who holds an instrument rating
  on the foreign pilot license issued by a contracting State to the
  Convention on International Civil Aviation may be issued an instrument
  rating on a U.S. pilot certificate provided:

  (1) The person's foreign pilot license authorizes instrument
  privileges;

  (2) Within 24 months preceding the month in which the person applies
  for the instrument rating, the person passes the appropriate knowledge
  test; and

  (3) The person is able to read, speak, write, and understand the
  English language. If the applicant is unable to meet one of these
  requirements due to medical reasons, then the Administrator may place
  such operating limitations on that applicant's pilot certificate as
  are necessary for the safe operation of the aircraft.

The "appropriate knowledge test" in this case is the Instrument Rating - Foreign Pilot test, it's described here with a few sample questions. Some more information is here, including the point that you don't need any prior authorization to take the test:

  • Requires NO instructor endorsement or other form of written
  authorization.

I'm not sure about the exact process involved (I guess you just do the test and send the certificate to the FAA) but the FSDO that validated your foreign license for VFR should be able to give you all the details.


What are the differences between Canadian VNCs and US Sectional charts?

The short answer is the charts are different because they're made by different groups - NAV CANADA has different charting standards than the FAA/NACO uses.

Similarly Jeppesen makes VFR charts for the United States, and they look very different from a FAA/NACO chart:

I have charitably described the Jeppesen VFR+GPS charts as "technicolor puppy vomit" on more than one occasion.

As far as I'm aware there's no comprehensive listing of all the differences between the US VFR Sectional format and the Canadian VNC format, but the NavCanada charts have a legend and there Canada Flight Supplement (CFS) contains a great deal of additional information - it's essentially similar to the US Airport/Facility directory.

Unlike the US charts, Canadian Aeronautical Charts--including the VNC--do not have a specific expiration date. They are revised periodically.


As long as the "Safety Pilot" possesses the qualifications and under the conditions listed below (from FAR 91.109):

  (c) No person may operate a civil aircraft in simulated instrument flight unless—

    (1) The other control seat is occupied by a safety pilot who possesses at least a private pilot certificate with category and class ratings appropriate to the aircraft being flown.

    (2) The safety pilot has adequate vision forward and to each side of the aircraft, or a competent observer in the aircraft adequately supplements the vision of the safety pilot; and

    (3) Except in the case of lighter-than-air aircraft, that aircraft is equipped with fully functioning dual controls. However, simulated instrument flight may be conducted in a single-engine airplane, equipped with a single, functioning, throwover control wheel, in place of fixed, dual controls of the elevator and ailerons, when—

      (i) The safety pilot has determined that the flight can be conducted safely; and

      (ii) The person manipulating the controls has at least a private pilot certificate with appropriate category and class ratings.


Fabric-covered Clark Y Max Coefficient of Lift

One contributor with a lightweight airplane like the C-3 is thrust.  At a high angle of attack, a significant fraction of the engine's thrust is directed downward, lightening the loading that the wing's lift is working against.  Even at idle, this allows slowing further before the angle of attack becomes critical -- making the coefficient of lift appear higher than it is.


What do I need to power up an EDF engine?

An EDF is an electric ducted fan, so I assume you're not interested in the fans powered by internal combustion engines (or actual turbines).

You'll need:

an ESC (electronic speed controller) that is rated for at least the maximum current and voltage of the motor in the EDF.
a battery that can provide that current and voltage.
something to provide a throttle signal to the ESC. Usually this is a transmitter and receiver, but for bench-testing a simple, cheap option is a servo tester.
a charger for the battery. This must be able to match the battery chemistry, voltage and capacity (they normally handle a range)
if the charger isn't mains powered, it will need a power supply.

There are loads of on-line shops for all this.


Do you have to worry about airborne disease on an international air flight?

I'm afraid you're probably not going to like the answer! And really, the model makes little or no difference.

The MITRE Corporation did some studies on this and a good summary can be found in the article
Detecting Aircraft Pathogens Before It's Too Late

The summary points are

  the researchers determined that most particles stayed suspended in the aisle, so when booking a trip, take a window seat

and

  Particles also did not travel far outside the contaminated row, and if they did, it was across the row. Previously, it was thought that contaminants would travel front to back, or back to front.

Most worryingly:

  The need for such sensors was evident in the 2003 outbreak of Severe Acute Respiratory Syndrome (SARS), which originated in an Air China flight from Hong Kong to Beijing, spread through 18 countries, and resulted in 774 fatalities. Asian economies suffered $11 billion in damages

As for controlling pathogens on board an aircraft, the CDC provide guidance which involves the same procedures you'd use on the ground (Hand washing, PPE, handling of bodily fluids).

Although air is no doubt filtered, as far as I know there is nothing special about the filters used on Aircraft that would be unique to aviation, nor offer any additional defense against airborne pathogens.


Am I correctly calculating the density altitude?

Check your temperature conversion: 25F is -3.9C...

Should be (25-32)*(5/9).


Can I log time in an RV-12 towards a commercial certificate, and is it a TAA?

Assuming that you are asking about the US, there are two parts to your question-total time and Complex/Turbine/TAA time.
As to whether the RV meets the requirements for a TAA that depends on what instrumentation/avionics it has. If it meets the definition, then you can use if for the training part of the aeronautical experience.

§61.129   Aeronautical experience.
(ii) 10 hours of training in a complex airplane, a turbine-powered
airplane, or a technically advanced airplane (TAA) that meets the
requirements of paragraph (j) of this section, or any combination
thereof. The airplane must be appropriate to land or sea for the
rating sought;

Further down in the reg it tells you what a TAA airplane is:

(j) Technically advanced airplane. Unless otherwise authorized by the
Administrator, a technically advanced airplane must be equipped with
an electronically advanced avionics system that includes the following
installed components:
(1) An electronic Primary Flight Display (PFD) that includes, at a
minimum, an airspeed indicator, turn coordinator, attitude indicator,
heading indicator, altimeter, and vertical speed indicator;
(2) An electronic Multifunction Display (MFD) that includes, at a
minimum, a moving map using Global Positioning System (GPS) navigation
with the aircraft position displayed;
(3) A two axis autopilot integrated with the navigation and heading
guidance system; and
(4) The display elements described in paragraphs (j)(1) and (2) of
this section must be continuously visible.

As for total time, read the regulation. An RV is an airplane so as long as you have at least 50 hours of the 250 in an airplane then you are good. You could do all 250 in the RV if you wanted.

(a) For an airplane single-engine rating. Except as provided in
paragraph (i) of this section, a person who applies for a commercial
pilot certificate with an airplane category and single-engine class
rating must log at least 250 hours of flight time as a pilot that
consists of at least:
(1) 100 hours in powered aircraft, of which 50 hours must be in
airplanes.…

You are no longer required to take the practical test in a complex or TAA airplane, so no matter what instrumentation/avionics it has you can use it for your practical.


Is there a cockpit which can recognize the voice of the pilot and help him/her to fly?

No, voice recognition is currently not used in aircraft as it would have to be built into the aircraft to pass certification for the aircraft and with rotating crews on aircraft, the voice recognition would need to be able to work with too many different voice types: high pitch, low pitch, male, female, accents, dialects and many more factors.

Voice recognition works because it learns from the user over time, something that is not possible in a cockpit environment with crew resource management.

There is a prototype in development by Honeywell at the moment, but it's in early stages of development.

Related reading:
The benefits of a Speech Recognition enabled cockpit by AdacelPDF


Where does Google Flights get its pricing information?

Google bought an airline pricing optimization
company called ITA Software that has interfaces with the GDS systems.


Is it better to have the engines center or apart on a plane?

the further apart the engines are, the worse becomes the yaw in an engine-out situation. but spacing them (and their fuel tanks) further apart along the span of a wing allows more even distribution of load stresses.


Does ground effect scale 1:1 with wingpsan?

It's most definitely not urban legend. However, it also does not scale 1-1 with wingspan. Rather, it scales nonlinearly with above ground height to span ratio ($h/b$). The simplest analytical prediction for ground effect can be derived from potential theory and the circulation theory of lift.

We know that the wing can be modeled as lifting line consisting of a line of vortex bound to the wing and trailing vortices that look like horseshoes. The trailing vortices induce downwash on the wing and everywhere else. But what about at the ground directly underneath the wing? Due to the tangency boundary condition of non-viscous flow, induced downwash must necessarily be zero everywhere on the ground.

Within the context of circulation theory of lift, the only way we can achieve this is if we have a mirror wing underneath the ground with the ground plane being the plane of symmetry, like this:

Since the image wing is exactly inverted, it produces upwash that reduces the overall downwash on the real wing. In the super simplified case of a single horseshoe vortex (which is incorrect), after some maths, the induced downwash at the wing root is now:

$$w_i=-\frac{\Gamma}{\pi b}\frac{16(\frac{h}{b})^2}{1+16(\frac{h}{b})^2}=w_{i_\infty}\frac{16(\frac{h}{b})^2}{1+16(\frac{h}{b})^2}$$

where $w_{i_\infty}$ is the downwash induced without the ground image (i.e. free-air). Turns out the latter factor is an ok approximation of total reduction of induced drag in ground effect as well. As you can see, at half wing span away from the ground, we have 80% of the free-air induced drag; at one full wing span away, we are at 94%. The effect falls away quickly.

You can read this MIT lecture on ground effect (from which I've taken the above diagram) for the derivation of the simplified ground effect prediction. More precise ground effect accounting can be found in references such as Raymer and ESDU Item 72023.


How are condensation cones created by supersonic airplanes?

It is important to note that the vehicle is not traveling at supersonic speed when condensation collars (rockets) or condensation cones (aircraft) occur. It is merely close to the speed of sound.

From the vehicle's viewpoint

Air is accelerated by the displacement effect of the vehicle - it pushes the air aside and around itself, causing the flow to accelerate and to become supersonic relative to the vehicle. This acceleration is directly connected with lower pressure (see this answer for a detailed explanation), and air with high relative humidity will be pushed beyond its dew point, causing the water vapor to condensate. Please note that the onset of condensation is slightly delayed, so the fog is not strictly indicating the region of lowest pressure. Also, the forward cone is not the same as the forward shock front of a lambda shock.

However, the rear boundary of the condensation is indeed caused by a shockwave. The low pressure area is instantly ended by a compression shock, when the supersonic flow around the aircraft is abruptly decelerated to subsonic speed by a compression shock. This raises the local air pressure back to around ambient pressure, so the capacity to absorb water is raised again and the fog evaporates. Again, this happens with a slight delay, so the end of the condensation area does not coincide with the compression shock but follows it.

From the viewpoint of the air

Since the low pressure area is caused by the aircraft, it travels with the aircraft, and so does the condensation effect. The air around the aircraft or rocket is accelerated towards the vehicle by its pressure field, which causes the condensation. Now the air is so fast relative to the vehicle that it is decelerated and recompressed by a straight shock, causing the condensation to disappear again.

Factors

A relatively blunt vehicle traveling at close to Mach 1 and humid, almost saturated air are the factors which help this effect to occur. Note that you can witness similar condensation effects over the wings of airliners in humid air during the landing phase, when flaps are fully deployed. Here, however, the condensation does not end abruptly, since no shock is involved. Also, the disturbances produced by the aircraft do not reach out so far at lower speed, so the condensation happens only close to the aircraft's surface. Bluntness helps: The cockpit causes its own small condensation area shortly past its maximum thickness, where suction due to displacement is highest.


Ryanair mainly buys their aircraft. Part of their ability to offer cheap flights comes from buying aircraft in bulk and generally only operating a single type of airframe.

They generally buy new Boeing aircraft operating primaraly the 737 series.

  ...had agreed to buy five more Boeing 737-800 aircraft, taking its order
  book to 180 new Boeing planes worth over $16 billion.

Planespotters.net has a nice list of the aircraft in Ryanair's fleet, with the exception of this -700 the rest of the aircraft only show registration to Ryanair as an owner under owner history.


Can I take my Canadian PPL with flight hours logged in the US?

This is a little excerpt from a Canadian document, as it relates to the conversion of licences back and forth between the two countries.

  The Agreement provides, in pertinent part, that the FAA and TCCA will pursue mutual cooperation in the evaluation and acceptance of each other’s systems and standards in the issuance of certificates and licences.

Keep in mind, this text is for conversion after you already have a full license, but I believe each country recognizes the hours in a log book from the other. Best bet would be to call or email the flight schools in the area you plan on going, and get the official word on it.

Edit: I should have put this here in the first place, but here is the link to the Conversion agreement between U.S. and Canada. You will find the snippet that I pasted in the 'Purpose and Scope' section.


Why is the TORA of 27R not the same as the TORA of 09L?

These seem to be the numbers of Heathrow / EGLL. When you look at the taxi diagram, you see that on 09L you have a taxiway that places you right at the beginning of the runway whereas on 27R when taxiing on A1 you end up juuust behind the start of the runway – probably 18m behind it.