Is the “competent observer” a required crewmember?

Yes, the "competent observer" is a required crewmember in that situation, by definition.

According to 14 CFR 1.1:

  Crewmember means a person assigned to perform duty in an aircraft during flight time.

Clearly, a "competent observer" operating as such under §91.109 (c)(2) is a person assigned to perform a duty in an aircraft during flight time; such an observer is therefore a crewmember. The operator is required to operate the aircraft with that observer performing their observation duties, and that person is therefore a required crewmember.

There are no other requirements as to who this person may or may not be other than the qualifying term "competent". The aircraft operator bears the burden of determining the observer's competency. One might argue that a certified pilot would be a competent observer.

An implied question here might be, is this competent observer a required crewmember that is able to log time for the performance of their duties? To this I would say, no, there is no provision in 14 CFR 61 for the logging of flight time for a person designated as an "observer", competent or otherwise.

EDIT to further explain the above paragraph in consideration of discussion in the comments: 14 CFR 61.51 allows pilots to log PIC and SIC time for flight in, among other conditions, "aircraft for which more than one pilot is required under the [...] regulations under which the flight is conducted". The "qualified observer" is indeed required in the situation in question, but need not be a pilot, and—unless otherwise qualified—is not acting as one of the required pilots in an "aircraft for which more than one pilot is required under the [...] regulations under which the flight is conducted". Obviously, if the person fulfilling the duties of a "competent observer" is otherwise also a required pilot, then the pilot may log the flight time as the required pilot.


Why do delta wings generate less lift at a particular angle of attack compared to straight wings?

No, a higher sweep angle will reduce lift even more.

All aerodynamic forces scale with the dynamic pressure, the product of air density and the square of airspeed, divided by half. If a wing doesn't produce lift, move to denser air or speed up.

However, drag will also scale with dynamic pressure, and there is more which influences lift. One is the angle of attack and the second is the suitability of the chosen wing geometry to produce lift at a given speed and angle of attack. Straight wings score best in this respect, at least at subsonic speed.

The sweep angle of the quarter-chord line gives you a first approximation of lift loss. Lift is proportional to the cosine of that angle. Just drive sweep to its extreme of 90°, and the inability of such a wing to create lift should become clear.

Lift is produced by the downward deflection of the air streaming around a wing. When the wing meets this flow straight on, it will have the biggest effect on the air and create the most lift. Any sweep, regardless of forward or backward, will reduce the wing's effect.

The next effect is the influence of the wingtips. If your wing extends sideways a lot more than it extends in flow direction, the influence of the tips is relatively lower. The ratio between wing span and chord is called the aspect ratio, and it figures prominently in the formula for the lift curve slope.


What are concrete examples for class G up to 14500?

It can be difficult to find these areas on a VFR sectional (there are very few of them anyway), but on an (FAA NACO) IFR en route chart they're shaded brown, so they stand out very clearly from the background. Here are a few grouped together in South Dakota.

IFR chart:

VFR chart:

At the western end of those areas there's a public airport, Bison Municipal (6V5):


What does it mean for a payload to be "caged"?

For something like a movable camera in a gimbal, or even a gyroscopic attitude indicator, it means that it is physically locked into place so that it can't move. On the gimbals (such as the camera pod in a predator, or other ISR asset) that can mean the camera is rotated into a stowed position, and then a pin is mechanically moved into place to keep the payload from moving.  This is usually done to prevent damage.

For a gyroscopic attitude indicator, you can generally cage it by pulling out a knob, and rotating it to a specific setting.  Again, this physically locks it into place so that it doesn't move.  This is usually done prior to shutting down as the mechanisms keeping the gyros spinning are powered down.  This is to prevent damage as well as give it a safe position from which to start from when power is re, applied to the aircraft.


What exactly is the purpose of a pilot keeping a logbook?

Almost everything in flying is measured in hours, including your experience.

To start with, in most places you need to have trained a certain number of hours before taking your flying skills test, regardless of how good you are.

And then it continues, want to do an instrument rating, you need x hours. Want to be an instructor, you need y hours. Want to be a Captain on a 747, well you'll need z hours as First Officer first and to be First Officer, you'll need....guess what!

Beyond that, many countries place restrictions on what you can and can't do based on your recent experience. For example, in the UK, to take passengers you must have performed three landings on type within 90 days.

And then it carries on outside of legislation, too - if you want to rent a plane most places will place some sort of hour requirement, whether it be your total hours or hours on type etc.

And so it follows that you need somewhere to log this. As a pilot your log book is sacrosanct - its a legal document forming a factual record of your flying experience.


How to determine the number of compression stages given a compression ratio?

You'll have to look up what the technology level can bring you these days. Usually, cycle design is s joint effort of what is needed and what can be done. Engine manufacturers have an aerodynamic department that is in close contact with the engine cylce designers and marketing.
An OPR (overall pressure ratio) of a design is based on the maximum turbine inlet temperature and depending on the cooling technology. Once selected, the aerodynamacists will tell you how many stages you're going to need. Since you're not a manufacturer, you'll need to choose a value, 1.2 : 1 is a value you can use. Note that a turbofan has a higher stage pressure ratio.


Why do commercial flights avoid overflying Shandong Province?

This is a guess, but it may be to avoid the restricted area ZSR-522 that covers airspace just north and east of the Shandong Peninsula. It's hard to say exactly, but it looks like your flight path more or less skirted around it, and the IFR chart suggests that the flight might have followed A326 east and then south from the ANRAT waypoint.

The Chinese AIP says (or said; that link may be out of date) that ZSR-522 is only up to 18000ft so in theory it's still well below typical airliner cruising levels. I've read several times, though, that the Chinese military control their airspace very tightly and they typically don't allow direct flight paths so perhaps they simply insist that aircraft must follow the airways because of 'national security' or some similar reason. Example:

  And the military's control of nearly all the airspace between Chinese
  destinations means that flights within China, even by the favored
  national carriers, sometimes must fly indirect routes that are the
  equivalent of going all around the city on a ring road.


What are the 2 protrusions next to the fore ground lights on the Tu-22M3?

They appear to be pitot tubes, part of the air data system.


Why does this holding pattern have both minimum and maximum altitudes published?

So that it keeps you under the shelf of the adjoining bravo airspace and because the decent gradient may be steep enough to require an upper limit. As discussed here:

The instrument approach procedure Holding Pattern In Lieu Of Procedure
Turn (HILPT) is designed to facilitate alignment with the final
approach course. The descent gradient from the HILPT altitude to the
Final Approach Fix (FAF) altitude is limited by TERPS criteria to
permit aircraft deceleration and configuration for the final approach.
Due to a combination of this descent gradient requirement and the
surrounding terrain, it may be necessary to employ a smaller than
desired holding pattern template to define the HILPT protected
airspace. Use of this smaller template may require the designation of
a maximum holding altitude on the 8260-2 Form. This becomes the
maximum altitude the aircraft is permitted to enter the HILPT unless
ATC can ensure obstacle clearance by keeping the aircraft at or the
minimum vectoring altitude (MVA) or the minimum

(source)
(red circle is roughly where the hold is, arrow points to minimum altitude)


How exactly are checklists shared between the pilots?

Typically, both pilots will set up "their" stuff as prescribed in the airline SOP's, and then the checklist will be called for.

At my airline, the captain has certain switches that he sets and certain systems that he checks -- generally things on his side of the overhead panel along with his flight instruments -- and the FO does likewise.  The FO performs the initial setup of the FMC, with both pilots checking what has been loaded (since some of the data comes in over a datalink).  Then, the captain briefs certain items, the clearance and routing are discussed, and then the captain calls for the checklist.  In flight, the flying pilot will call for the checklist (although if he's late in calling for it, the monitoring pilot my suggest, "are you ready for the Descent Checklist").

At my airline, the FO (or, in flight, the monitoring pilot) reads each item on the checklist, both pilots verify the switch or condition, and the captain responds.  Everything in the checklist is standardized, so the responses are predictable.  For instance, if the Before Takeoff checklist challenge is "Anti-ice" then the response might be "Off" or "Engine On, Wing Off" (since you don't operate on the ground with Wing anti-ice turned on in the 737).  But both pilots should be looking at the switch position to confirm that what is actually set (a) makes sense, given the conditions, and (b) matches what the Captain states.

Other operations will have some variation in this.  In another organization, the challenge "Altimeters" was answered "30.03, Pilot" followed by "30.03 Copilot" and then "30.03 Navigator".  Where I am now, we'd simply have both pilot check that the altimeters all match the ATIS setting, and the captain responds "30.03, set".  Either method works in a 2-pilot aircraft; with a Navigator and a Flight Engineer and a Loadmaster, crews in my old aircraft did things a little differently, in ways that made good sense in that operation.

So yes, the precise details of how all this is done are very aircraft- and airline-specific.


You can request Flight Following at anytime.

Personally, I wouldn't be in a hurry to request it as soon as you depart. Wait until you're established on course, in a cruise-attitude (instead of a climb), and everything is settled and running smoothly. Then know your position, and how you're going to report it. Know where you're going (both by name and ICAO identifier), and try to anticipate any questions they might ask.

Look for the Center/Approach/Depature where you are (look in your chart supplement for an airport close to you), and call up with:

You: "Seattle Center; November 12345: VFR, with request"
translation: Calling Seattle Center, this is N12345. I'm VFR (so you haven't heard from me before... don't be surprised!), and I have a request.

Center: "November 12345: Say request."

You: "November 12345 is SkyHawk, 10 mi. South of Harvey Field, 4,500 feet. Request VFR Flight Following to Friday Harbor"
translation: I'm a Cessna Skyhawk, my location and altitude will help you find me. I'm asking for FF to this other airport."

Center: "N345: Squawk 4532 and Ident."

You: (Set your transponder to 4532, press the Identify Button), and say "4532 and Ident, N345"

Center: "N345: Radar Contact, 11 mi. south of Sierra Four Tree, at 4,500. Traffic at your 1o'clock, 5 mi. North Bound, Altitude indicates 3,000."translation: I found you on my radar scope, and am describing the position I see you. (If you disagree, speak up!). You have traffic ahead and slightly to your right. Their transponder indicates 3,000 feet, but I cannot independently verify that.


Why does the helicopter's nose go down when the cyclic is pressed forward (in a hover)?

I think you might be confused by what the hinges do.  In the example you show, the teetering hinge, which is only present in 2 blade rotors, causes both blades to tilt, or "teeter" or see-saw, together.  It is not possible for both blades to rise or fall in normal operations.  The feathering hinge is not really a hinge at all.  It is a bearing in the blade cuff which enables to blade pitch angle to change, caused by the position of the swash plate, by rotating the blade within it's cuff.

Consider a helicopter hovering in a no wind situation - simply because adding wind needlessly complicates the explanation.  I will also assume a counter-clockwise rotating rotor.  Simply reverse the explanation for a clockwise rotor.

The total thrust vector of the rotor is vertical, perpendicular to the centre axis of the disc.  It has a zero horizontal component so no force is applied longitudinally or laterally to the helicopter and it remains in a fixed position.

When you push the cyclic forward, the pitch of the blade at the leftmost position is increased, increasing the angle of attack and therefore the lift.  Due to precession, the blade rises at the back of the disc and falls at the front, tilting the entire disc forwards.

The total thrust vector remains perpendicular to the disc and since the disc is tilted with respect to the fuselage, is now comprised of horizontal and vertical components.  It is the horizontal component which accelerates the helicopter in the direction of the tilt.

So there is a force (lift) lifting the rear of the disc and lowering the front.  This force is transmitted through the rigid rotor drive shaft and pushes the nose down and pulls the tail up. Another way to think about this is that you are applying a force at the top of a lever, the drive shaft, which is above the centre of gravity and therefore causes the fuselage to rotate in pitch. The helicopter will continue to accelerate until the additional drag equals the horizontal component.

Helicopters also employ horizontal stabilisers which produce lift to push the tail down with increasing airspeed so the nose down pitch in cruise is reduced.

Therefore, pushing the stick forward and holding it at some attitude (when flying VFR you select a speed by adopting the nose down attitude for that speed which is learned from experience and practice followed by small trimming to hit the desired speed) will cause the nose to pitch down and the aircraft to accelerate until the trimmed speed is attained.


How does changing the altimeter setting in the US and elsewhere compare?

Indeed the US and the rest of the world handle this differently.

In the US, if you are cleared to a flight level or altitude, you change the altimeter setting as you are about to cross the transition level (18,000 @ 29.92).

  [When] descending, even if cleared to an altitude at the time the cruising level is vacated, the altimeters will remain on standard pressure until just prior to the transition level.

Unless cleared in a climb to FL180, then the change is done a bit earlier.

In Europe and elsewhere, the change of the altimeter setting is done as soon as you start climbing or descending to the cleared flight level or altitude.

  climbing and cleared to a FL - set Standard Pressure Setting (QNE/1013 mb);
  descending and cleared to an altitude - set QNH.

Between the TA and TL no altitude/level can be assigned. If the local pressure is too low, what floats (rises) is the TL.

The same for the US:

  If the altimeter setting is lower, the lowest useable FL becomes FL190 or even FL200.  This restriction ensures that a minimum of 1000' vertical separation is maintained between the aircraft at 17000' on QNH and the one at the lowest useable level on Standard Pressure Setting (QNE).

If the TL is FL150 as in your example, you will not be cleared to 15,000 feet. You will be cleared to FL150. Based on the above, you will maintain 1013 (QNE) until cleared to an altitude. The same for the US, you won't be given an altitude of 18,000, it will be FL180 whether going up or down.

(Image source)

Source: SKYbrary.aero


How close to the envelope and the ideal was US1549 on ditching in the Hudson?

The configuration of the A320 for ditching with no engines running is CONFIG 3. I don't know how familiar are you with the flap configurations on A320, so I will start from the beginning. The flap lever has five positions: 0,1,2,3 and FULL (two configurations correspond to position 1-> CONFIG 1 and CONFIG 1+F).
In the CONFIG 3, which is the preferred method for ditching, the slats are extended to 22 degrees and flaps are down by 20 degrees. Config FULL, has slats down to 27 degrees and flaps down to 40 degrees. Look at the difference between flap deflection in CONFIG 3 and CONFIG FULL, that's 20-degree change in flaps. The 20-degree change will make a lot of impact on the drag of the aircraft and its vertical speed at the moment of impact. Therefore, CONFIG 3 is preferred. I must note that CONFIG FULL will not decrease the stall speed by a large amount: from my experience, it will decrease it by about 5 knots or a maximum of 10 knots. But definitely not more than that. The US airways flight 1549 had flaps down to CONFIG 2, below the ideal state.

If the ditching is performed with engine thrust, the suggested configuration for ditching is then, obviously, CONFIG FULL because we can trade engine power for the lowest possible approach speed which, for flight 1549, was not the case.

Flight 1549 was pretty close to the stall speed. On the video below you can see the approximate speed at the moment of impact. The exact touchdown speed was 125 knots.

With dual engine failure on Airbus A320, the aircraft will revert to alternate law, but due to the captain's fast reaction to turn on the APU, aircraft remained in normal law, assisting the pilot to not stall the aircraft. This does not mean that if the pilot pulls all the way back at such low altitude that no stall will occur. Upon landing/touchdown normal law goes gradually out and the FBW system introduces a nose-down pitching moment, so the pilot will not balloon the aircraft. In the last seconds before touchdown, the computer gradually returns to direct law, giving the pilot more feeling over the pitch. In this abnormal scenario, it is difficult to judge exactly what the FBW would do since this "reverting the pitch control to direct law" thing is characterized by the FLARE mode on the FMA, and I am not sure if the FBW system met requirements for that mode. If normal "reverting to direct law" occurred then the pilot would have been able to stall the aircraft just before the touchdown. If it did not occur, due to all abnormalities that occurred to the aircraft, the pilot would not be able to stall the aircraft.
The plane definitely does not know the correct pitch for ditching, neither what the crew was attempting to do. In ditching, the best pitch attitude for A320 is 11 degrees. In the answer that you linked, I can see that for 11-degree pitch attitude, the aircraft at the given weight is descending at -1 degrees, which makes the angle of attack equal to 12. Look the accident flight, angle of attack was 13 degrees, by the same analogy. That means that the aircraft was slower than ideal although the speed was 7 knots higher (due to the takeoff weight of the aircraft). The point is, given its weight the aircraft should have flown faster (than 125 knots) and the pilot should have pitched the nose of the aircraft higher, to match the preferred attitude of 11 degrees.
Stall pitch should be higher than the actual pitch for the ditching.


Where do I place pressure ports on an airfoil?

Depends on what you want to measure.

Normally, pressure ports are bunched close to the leading edge to give sufficient resolution of the steep pressure gradients (which result from the high local curvature). So scale the local pressure port distance with local curvature.

But maybe you want to have a high resolution of the beginning flow separation near the trailing edge? Then you need to place the pressure ports close to the trailing edge.

Or maybe you want to study the laminar to turbulent boundary layer transition at mid-chord? Then any pressure ports in the laminar region will cause a local transition and show a 15° cone of turbulent flow which will mess up all other measurement behind them. Now you need to restrict the number of ports in the forward part of the airfoil and need to give them enough lateral separation to get what you want.


Why don't American passenger airlines operate dedicated cargo flights any more?

Alaska Airlines, Hawaiian Airlines still have dedicated freighters.

American, Delta, Southwest and United all have thriving cargo shipping operations, but as far as I can tell, no longer have freighters.

https://www.aacargo.com
https://www.alaskaair.com/content/cargo/general
https://www.deltacargo.com
https://www.hawaiianaircargo.com
https://www.swacargo.com

Alaska used to run 737 Combi to ship cargo and passengers in the main cabin on their “Milk Run” up the Alaskan panhandle. They now have dedicated freighters to handle the cargo.

https://thepointsguy.com/2017/10/final-flight-alaska-airlines-737-400-combi/

Good luck shipping your parcel.


Should I log flights on separate lines if I park the plane between legs to different airports?

There are no hard and fast rules in the US about how and when to break up a flight like this, so do what makes the most sense to you.
In the military I would generally log individual sorties on different lines because there were varied mission codes, and sometimes we switched crews.  However, on a multi leg cross country I would log it all on a single line.  (As long as the multiple legs occurred on the same day.)


Is there a minimal legal ground clearance to use an international airport?

For propellers, there is a minimum ground clearance according to the EASA Easy Access Rules for Normal, Utility, Aerobatic and Commuter Category Aeroplanes (CS-23):

  CS 23.925 Propeller clearance

  Propeller clearances with the aeroplane at the most adverse combination of weight and centre of
  gravity and with the propeller in the most adverse pitch position, may not be less than the following:

  (a) Ground clearance. There must be a clearance of at least 18 cm (7 in) (for each aeroplane with
  nose wheel landing gear) or 23 cm (9 in) (for each aeroplane with tail wheel landing gear)
  between each propeller and the ground with the landing gear statically deflected and in the
  level, normal take-off, or taxying attitude, whichever is the most critical. In addition, for each
  aeroplane with conventional landing gear struts using fluid or mechanical means for absorbing
  landing shocks, there must be positive clearance between the propeller and the ground in the
  level take-off attitude with the critical tyre completely deflated and the corresponding landing
  gear strut bottomed. Positive clearance for aeroplanes using leaf spring struts is shown with a
  deflection corresponding to 1.5g.

  (b) Aft mounted propellers. In addition to the clearance specified in sub-paragraph (a) an aeroplane
  with an aft mounted propeller must be designed such that the propeller will not contact the
  runway surface when the aeroplane is in the maximum pitch attitude attainable during normal
  take-off and landings.

So 18cm seems to be the minimum ground clearance for propellers on most aircraft (e.g. ATR-42).

It is hard to prove a negative, but the section about turbojets and turbofan engines does not list any minimum.


What’s the difference between “approved” and “legal” procedure?

The AIM is not regulatory, just best practices approved by the FAA. You should do what the AIM says, but as PIC you are free to ignore it.

The FARs are regulatory, so as long as you don't violate them, what you're doing is legal. You must do what the FARs say (unless you have an emergency, of course).

In the case of pattern entry, other pilots are expecting you to do what the AIM says (45 to downwind), so doing something different is probably unsafe--especially if you aren't in radio contact. But if there is nobody else in the pattern, that reason doesn't apply and it is safe to enter however you wish (straight in, crosswind, etc.). It is up to you as PIC to make this decision.

The same logic is true generally: if you understand why the AIM says to do (or not do) something, you probably understand when it's okay to ignore it.


Is it common to change the type of engine during major overhauls?

Not common but not unheard of. Overhauls are the major avenue by which older aircraft variants receive upgrades, effectively becoming newer variants (or functionally equivalent to them). Engine upgrades can be one of the easier changes to make, assuming the new engine was designed to be a "drop-in replacement" (mounts and fuel/electrical connections identical, so you just bolt it on possibly with a token change to the housing). Other changes between variants can be much more in-depth, like stretching the fuselage or altering wing length and profile, which are not typically done to aircraft that have already entered service.

In GA, this tends to be more common, as many of the airframes in the GA fleet are decades old (thanks to strict maintenance requirements keeping them serviceable much longer than the expected useful life of a car), and so the benefit of more modern technology of all kinds, including in the engines, tends to justify the costs. Major airlines very rarely do this kind of thing, especially with engines, as jet engines are ridiculously expensive, and when the engine's reached the end of its useful service life, the airframe usually isn't far behind. It's sometimes done to really big, really expensive aircraft like 747s, and the military has done a few "service life extension programs" that involve replacing engines on venerable airframes like B-52s and C-130s.

As far as invalidating ratings, well yes, the original aircraft specs in the POM would no longer apply after an up-engine. The aircraft, as a unit, must be re-rated both theoretically and empirically by an FAA inspector to determine its new specs, and whether all the components of the aircraft can handle them safely (a more powerful engine does not necessarily mean the aircraft can be rated for a higher "do not exceed" speed, if the limiting factor wasn't the engine but the airframe's ability to take the stress). The easiest types of upgrades to get approved are ones that turn the aircraft into a more powerful factory variant of the airframe; for instance, dropping a 235 engine into what used to be a Cherokee 180. With a few other tweaks to bring the entire aircraft up to the specs of a 235, it can be evaluated as if it were one.


How does a hot tip-jet supply fuel to its engines?

There are pipes inside the blades which connect the engines to a rotary seal inside the main rotor head assembly. That seal allows fuel to be pumped into the blades from a port outside the main rotor head. Such seals are used in a variety of mechanical engineering applications where a fluid, usually lubricating oil, has to be provided to a rotating piece of machinery.
One example which you can probably find a cross-section of on the web is the method of using oil under pressure to change the blade pitch of a constant-speed propeller.


Wouldn't a Snow Globe prevent pilots from getting disoriented?

This doesn't work. A plane can be in arbitrary orientations while the the forces felt by everybody in the plane are directed straight at the floor. A famous example is Bob Hoover pouring tea while rolling a plane. If Bob Hoover's tea can't tell that it's being poured upwards, nor can your snowglobe.  Indeed, this is precisely why pilots become disoriented.


Where to find information on the Daimler-Benz 606/610?

Each of those is two V12 engines coupled together.

The 606 is two 601s:

  Two DB 601 F or G coupled to work on a single propeller shaft for use in early Heinkel He 177As - 2,700 PS (1,986 kW) at sea level with a mirror-imaged starboard component engine supercharger, and derided as "welded-together engines" by Reichsmarschall Hermann Göring in August 1942, from the problems they caused with engine fires in the He 177A during service from their inadequate installation design; such problems were not present in either the Heinkel He 119 and Messerschmitt Me 261 which also used them.—Wikipedia

The 610 is two 605s:

  Two DB 605 "coupled" (geared together) as a "power system" (71.53L / 4364.8in3), to work on a single propeller shaft for use in Heinkel He 177, up to 2950 PS (2,909 hp) for take off, 2788 PS (2,750 hp) at 2,100 m. Mirror-imaged starboard component engine supercharger.—Wikipedia

The "engine difficulties" section of the Heinkel He 177 Wikipedia article discusses the story of both engines. The 606 was notorious for catching fire when installed on the He 177, and later it was replaced with the 610.

You can get more information by looking up 1) which aircraft they were installed on, or 2) the 601 and 605 base models.

(Image source)


How do aircraft follow the tarmac lines while taxiing?

For most aircraft:
It is just something that you learn. As you approach a line, you have a general sense of where the line is, because you can see the line continue in front of you. This also applies to turning, where you are familiar with the turn radius, and have a sense of where it is. It is similar to a car, in that you can drive down the center line of the road, and still know it is underneath. Scale is just increased.

For tail-draggers:
A tail-dragger is an aircraft that has two front wheels, and one rear wheel, meaning the aircraft is typically pitched up when on the ground. In this situation, the pilot zigzags across the taxiway, looking roughly 30 degrees front left or front right, checking the area in front of him. This isn't so much for following the line though, as it is for ensuring you're not about to hit anything in front of you.

Please let me know if there are any clarifications I can add!


What are the major aircraft systems (LRUs) using the ARINC429 Protocol?

On modern aircraft all equipments that needs to communicate to each other in binary format may use ARINC 429 protocol. For instance all fly by wires computers on Airbus 320, 330, 340 use arinc 429 protocol.

Nowadays other protocols do exist too such as arinc 629 protocol or fiber optic protocols etc.

As a summary all aircraft systems that need to transmit and receive binary data may use 429 protocol, but other digital protocols are possible.

However a standardized LRU that doesn’t use ARINC 429 protocol is the FDR ( flight data recorder), because the data that it receives is already sequentially ordered, the label is not transmitted with the data value

On the following website starting page 43 you find all the possible equipment that may use A429

http://read.pudn.com/downloads111/ebook/462196/429P1-17_Errata1.pdf

Also in the same document starting page 13 you have the list of the parameters that may be transmitted on A429

Hope this added information is helpful


How can I calculate maximum rate of climb?

To calculate your possible climb speed $v_z$, you will need

Your engine's thrust $T$
Your airplane's drag $D$
Your airplane's mass $m$

Calculate how much power is needed to overcome drag, and any excess can be used for climbing: $$v_z = v\cdot sin\gamma = v\cdot\frac{T-D}{m\cdot g}$$

Note that this equation makes use of several simplifications, but works well for propeller and slow turbofan aircraft with moderate flight path angles $\gamma$.

To do this with more precision, you need to account for the fact that the aircraft should accelerate during the climb to stay at the same polar point. Now you further need:

The gradient of air temperature over altitude (lapse rate $\Gamma$)
The local speed of sound $a$, and
The gas constant $R$ of air.

You need to add a correction factor $C$ which has several components: $$C = 1 + \frac{1}{2}\cdot\kappa\cdot R_w\cdot\Gamma_w\cdot Ma^2 + \frac{(1+0.2\cdot Ma^2)^{\frac{\kappa}{\kappa-1}}-1}{(1+0.2\cdot Ma^2)^{\frac{1}{\kappa-1}}}$$

where $\kappa$ is the ratio of the specific heats of air and is 1.405, the index w denotes the wet adiabatic gas constant and lapse rate of air, and $Ma$ is your flight Mach number. $\Gamma$ can vary between -0.004°/m and -0.0097°/m, but if you use the average of -0.0065°/m, this equation can be simplified to: $$C = 1 - 0.13335\cdot Ma^2 + \frac{(1+0.2\cdot Ma^2)^{3.5}-1}{(1+0.2\cdot Ma^2)^{2.5}}$$

which is probably the form you will find in most books which care to cover this topic. The second summand takes care of the reduction of atmospheric temperature with altitude and disappears in the stratosphere, and the third summand covers the additional energy needed for acceleration in terms of flight Mach number.

Acceleration factor over the flight Mach number in the troposphere for the Standard Atmosphere

Now your climb speed becomes $$v_z = \frac{v}{C}\cdot sin\gamma = \frac{v}{C}\cdot\frac{T-D}{m\cdot g}$$

As you can see from the graph above, the correction factor is only important at higher speeds, but will cut the climb speed in half at Mach 2. Some jet aircraft need to climb at a high constant Mach number, and then the aircraft needs to decelerate while climbing. Now the correction factor becomes smaller than unity and the climb speed gets a boost because kinetic energy is converted into potential energy while climbing.

Optimum speeds

To pick the flight speed where the climb speed or the fight path angle reaches a maximum, you now need to describe how thrust will change with flight speed. To simplify things, we can say that thrust changes over speed in proportion to the expression $v^{n_v}$ where $n_v$ is a constant which depends on engine type. Piston aircraft have constant power output, and thrust is inverse with speed over the speed range of acceptable propeller efficiencies, hence $n_v$ becomes -1 for piston aircraft. Turboprops make some use of ram pressure, so they profit a little from flying faster, but not much. Their $n_v$ is -0.8 to -0.6. Turbofans are better in utilizing ram pressure, and their $n_v$ is -0.5 to -0.2. The higher the bypass ratio, the more negative their $n_v$ becomes. Jets (think J-79 or even the old Jumo-004) have approximately constant thrust over speed, at least in subsonic flow. Their $n_v$ is around 0. Positive values of $n_v$ can be found with ramjets - they develop more thrust the faster they move through the air.

The flight speed for maximum rate of climb ($v_y$) is reached at a lift coefficient $c_L$ of $$c_L = -\frac{n_v+1}{2}\cdot\frac{T\cdot\pi\cdot AR\cdot\epsilon}{m\cdot g}\cdot \sqrt{\frac{(n_v+1)^2}{4}\cdot\left(\frac{T\cdot\pi\cdot AR\cdot\epsilon}{m\cdot g}\right)^2 + 3\cdot c_{D0}\cdot\pi\cdot AR\cdot\epsilon}$$

whereas the steepest climb is possible with a $c_L$ of $$c_L = -\frac{n_v}{4}\cdot\frac{T\cdot\pi\cdot AR\cdot\epsilon}{m\cdot g}\cdot \sqrt{\frac{n_v^2}{16}\cdot\left(\frac{T\cdot\pi\cdot AR\cdot\epsilon}{m\cdot g}\right)^2 + c_{D0}\cdot\pi\cdot AR\cdot\epsilon}$$

Nomenclature:
    $c_L \:\:\:$ lift coefficient
    $T \:\:\:\:$  thrust
    $m \:\:\:\:$  aircraft mass
    $g \:\:\:\:\:$  gravity
    $\pi \:\:\:\:\:$  3.14159$\dots$
    $AR \:\:$  aspect ratio of the wing
    $\epsilon \:\:\:\:\:$  the wing's Oswald factor
    $c_{D0} \:$  zero-lift drag coefficient


What are some ways to decrease turbulence?

There is no way to really decrease turbulence per-se since its a factor of the air around you. There are ways to mitigate its effects and some are.

Climb: In some cases the air higher up is less turbulent or you can climb over the weather system causing the turbulent air. In this case climbing to a higher altitude may help
Divert: Similar to the climb situation you can divert around the turbulent air if you know where its occurring.
Timing: This is the one you may have the least control over if you are talking about commercial flying and its not always true but generally speaking the winds and thermal activity tend to be calmer in the early morning and evening. Flying around these times may allow you to find smoother air.
Size: Again this one is hard to control but there is some truth to the fact that big planes will be less effected by turbulent air than small planes. By this I mean that a 777 is going to bump around less than a Piper Cherokee. But it holds more or less true across the board.


Was the transatlantic crossing for Concorde too short to reach optimal cruising altitude?

The simple answer is that the Concorde had no single assigned altitude, it was allowed to climb freely above ~FL450; this is discussed in depth in episode 166 – Flying the Concorde (worth the listen as it answers just about every Concorde question!). As @pilothead alludes to in their answer it climbed as it burned fuel but the aircraft never actually initiated a climb, it simply drifted up as it burned fuel and became lighter.

Also discussed in the episode is the complex approach and departure procedure. Due to the fuel burn schedule the Concorde did not really have the ability to hold for more than a single lap in a holding pattern or do a stepped climb with some route adjustments like many airliners. They had a special departure procedure that was more or less runway to cruise with no interruptions and a similar descent option. So the flight was effectively a climb to cruise block then a glide down right to landing. Depending on the wind and conditions of any given day as well as the load on board, the cruise altitude could vary greatly.


What restrictions apply in international airspace?

When a US registered pilot is operating in international airspace, he is bound by both the US aviation regulations (14 CFR) and ICAO Annex 2, as required by 14 CFR 91.703.  It also requires compliance with MNPS and RVSM airspace rules where appropriate.

  Sec. 91.703 - Operations of civil aircraft of U.S. registry outside of the United States.

  (a) Each person operating a civil aircraft of U.S. registry outside of
  the United States shall--
  (1) When over the high seas, comply with
  annex 2 (Rules of the Air) to the Convention on International Civil
  Aviation and with Secs. 91.117(c), 91.127, 91.129, and 91.131;
  (2) When within a foreign country, comply with the regulations relating to
  the flight and maneuver of aircraft there in force;
  [(3) Except for
  Sec. Sec. 91.117(a), 91.307(b), 91.309, 91.323, and 91.711, comply
  with this part so far as it is not inconsistent with applicable
  regulations of the foreign country where the aircraft is operated or
  annex 2 of the Convention on International Civil Aviation; and]
  (4) When operating within airspace designated as Minimum Navigation
  Performance Specifications (MNPS) airspace, comply with Sec. 91.705.
  When operating within airspace designated as Reduced Vertical
  Separation Minimum (RVSM) airspace, comply with Sec. 91.706.

  (b) Annex
  2 to the Convention on International Civil Aviation, Ninth
  Edition--July 1990, with Amendments through Amendment 32 effective
  February 19, 1996, to which reference is made in this part, is
  incorporated into this part and made a part hereof as provided in 5
  U.S.C. Sec. 552 and pursuant to 1 CFR part 51. Annex 2 (including a
  complete historic file of changes thereto) is available for public
  inspection at the Rules Docket, AGC-200, Federal Aviation
  Administration, 800 Independence Avenue SW., Washington, DC 20591; or
  at the Office of the Federal Register, 800 North Capitol Street, NW.,
  Suite 700, Washington, DC. In addition, Annex 2 may be purchased from
  the International Civil Aviation Organization (Attention: Distribution
  Officer), P.O. Box 400, Succursale, Place de L'Aviation
  Internationale, 1000 Sherbrooke Street West, Montreal, Quebec, Canada
  H3A 2R2.

Another unrelated FAA document explains it in plain language:

  International Civil Aviation Organization (ICAO)

  ICAO is an agency of the United Nations that originated from the
  signing of the Convention on International Civil Aviation in December
  1944 (referred to as the Chicago Convention). This organization was
  formed to promote the safe and orderly development of international
  civil aviation. The Chicago Convention produced International
  Standards and Recommended Practices (SARP) aimed at standardizing
  international civil aviation operational practices and services.
  Currently, these SARP's are contained in 18 annexes to the Chicago
  Convention. In particular, Annex 2, Rules of the Air, and Annex 11,
  Air Traffic Services, are pertinent to this paper as they relate to
  civil aircraft operations, the establishment of airspace, and air
  traffic control (ATC) services in international airspace. Although not
  addressed in this paper, it should be noted that the SARP's are
  augmented by various ICAO documents containing Procedures for Air
  Navigation Services (PANS) that amplify the basic principles in the
  SARP's. Further, to supplement the worldwide procedures contained in
  the annexes and PANS, ICAO develops Regional Supplementary Procedures,
  which are part of the Air Navigation Plans agreed upon to meet the
  needs of specific geographical areas.

  Two articles of the Chicago Convention also have a bearing on the
  subject of this paper:

  Article 3:

  Exempts state-owned aircraft (which includes military aircraft) from
  the provisions of Annex 11 and its Standards and Recommended
  Practices. (Note: As an ICAO Contracting State, the U.S. has agreed
  that its state aircraft will be operated in international airspace
  with due regard for the safety of civil aircraft.)

  Article 12:

  Obligates each ICAO Contracting State to adopt measures to insure that
  persons operating an aircraft within its territory shall comply with
  that state's air traffic rules; or with Annex 2, Rules of the Air,
  when operating over the high seas. The U.S. satisfied this
  responsibility through Title 14, Code of Federal Regulations (CFR)
  Part 91 which requires that operators of aircraft comply with U.S.
  operating rules when in the U.S., and that U.S.-registered aircraft
  comply with Annex 2 when over the high seas (see section 91.703).
  However, section 91.703 applies only to civil aircraft, and state
  aircraft operating outside the U.S. are only subject to the "due
  regard" provisions of Article 3 of the Convention.

  Under ICAO agreements, the SARP's in Annex 11 apply to airspace under
  the jurisdiction of a contracting state which has accepted the
  responsibility of providing air traffic services over the high seas,
  or in airspace of undetermined sovereignty.


What is garbling in the context of radar?

Garbling occurs when two aircraft are close enough that their replies overlap, as there is no reliable way to sort them out. Usually this occurs when the aircraft are passing above each other as the radar scans the entire vertical column at once, only rotating horizontally.

The problem is that the controller might not be able to check the aircraft are indeed flying their correct assigned altitudes exactly at the moment when it matters most when they are passing above each other.

Quick Googling reveals e.g. this article with some diagrams of the overlapping signals.

A related problem is “fruit”, which is the squawks triggered by other things than the radar beam (e.g. the interrogations from T-CAS on other aircraft) being mistaken for ones that were, and therefore making the aircraft appear at other place than it really is.

Both issues are mitigated by ADS-B, because there the aircraft broadcasts at semi-random points and includes it's own position, so while the messages may still conflict (like in other transmission protocols), the timing is designed to make it unlikely to happen for several following messages.


How can landing in zero visibility be safe?

Such landing is safe, reasonable and completely standard business.

The ILS transmitter is rather simple, so there is not that much that can go wrong. But to qualify as category III, only which can be used with no decision height, it additionally needs monitoring circuits that check whether the correct signal is being transmitted and shut it down if it transmits incorrect signal. There is a strict limit how fast the monitoring circuit must react and the whole system is regularly tested. The monitoring system is already needed for category II, but with weaker limits for reaction time. Additionally the tower ensures no other aircraft and vehicles move in area around the transmitters where they could affect the signal propagation.

On the aircraft side for auto-land dual channel autopilot is required. So there are two systems that decode the signal and calculate the control input. If the systems disagree or if the signal fails, alarm is sounded and the pilot flying will initiate a go-around.

The controller on tower sees the aircraft on radar, so can verify that the aircraft is indeed approaching the intended runway. If the signal fails in the very last moment and there is not enough time to go around until wheels touch the ground, the aircraft won't have time to divert from course significantly, so the wheels still touch down on the paved surface. If the lateral signal fails during roll out, there is some risk of runway excursion, but that's what the safety areas are for. Runway excursions (to the sides; overruns are another matter, but they are not significant risk here) rarely result in injuries.

This is really the same level of safety as for any other system you rely on like engines or hydraulic flight controls and many other systems in the aircraft.

Note that since there is no taxi guidance, landing in zero visibility is not really possible anywhere (except, as raportech97 correctly noted below, in emergency). Some visibility is always needed (50 m should be the lowest, airport and aircraft equipment permitting) that also gives pilots chance to manually control the roll out in case of localizer failure in that phase.


Would a wireless fly by wire system be practical?

The fly-by-wire is absolutely vital for control of the aircraft, and the three dominating factors here are safety, safety and safety. Weight is not one of them. The fly-by-wire system is triple or quad redundant: instead of removing a set of cables, the manufacturers are installing 3 more cable looms, just to make sure that the system always works.

Wires are safer than wireless!. There are active transmitters and receivers in wireless systems, which can fail. Signal reception depends on the quality of the space between transmitter & receiver: can the signal always penetrate the aluminium bulkhead? What happens to the wireless signal when flying past airport radar or in the weather radar field of another aircraft?

Shielded wires are passive and relatively immune to electro-magnetic radiation, and are the means of choice for such a safety critical system.

Update

The OP was on fly-by-wire. In a sense, the flight control system is the most safety critical system on board and must be immediately available at all times. The presentation linked to by @mins in a comment reports on the progress of on-board wireless communication, for systems with a less critical safety aspect:

  Examples of Potential WAIC Applications

  Low Data Rate, Interior Applications (LI):

    Sensors: Cabin Pressure - Smoke Detection - Fuel Tank/Line – Proximity Temperature - EMI Incident Detection - Structural Health Monitoring - Humidity/Corrosion Detection
    Controls: Emergency Lighting - Cabin Functions

  Low Data Rate, Outside Applications (LO):

    Sensors: Ice Detection - Landing Gear Position Feedback - Brake Temperature - Tire Pressure - Wheel Speed - Steering Feedback - Flight Controls Position Feedback - Door Sensors Engine Sensors - Structural Sensors

  High Data Rate, Interior Applications (HI):

    Sensors: Air Data - Engine Prognostic - Flight Deck/Cabin Crew
    Images/Video
    Comm.: Avionics Communications Bus - FADEC Aircraft Interface - Flight Deck/Cabin Crew Audio / Video (safety-related)

  High Data Rate, Outside Applications (HO):

    Sensors: Structural Health Monitoring
    Controls: Active Vibration Control

From the same presentation: An A380 has 5,700 kg of wires on board, and 30% of them are potential candidates for a wireless substitute. So wireless communication on board of aircraft does make sense, starting with the non-safety critical systems first.


Do commercial airlines have procedures for evacuating pets from the cabin in an emergency?

There are no policies because pets are technically cargo/baggage as you note in the question, and treated as such. In other words in case of an emergency evacuating the passengers is a priority and as you would be instructed to leave your baggage behind you would more than likely be instructed to leave any pets behind.

  The Federal Aviation Administration (FAA) allows each airline to
  decide if they will allow you to travel with your pet in the passenger
  cabin. If an airline does allow you to bring your pet into the cabin,
  we consider your pet container to be carry-on baggage and you must
  follow all carry on baggage rules (14 CFR part 121, section
  121.589)

The exception to this is service animals which are not treated as pets.

  Service animals are not pets. They are working animals that assist persons with disabilities.


What are these aircraft at the Naval Air Weapons Station China Lake?

This answer is a Community Wiki.
Community edits are welcome.

The aircraft in the photo appear to be the following, or varients therof:

Douglas R4D-8 (Super DC-3)

source, photographer: Brian Lockett

North American T-39 Sabreliner
Boeing C-97 Stratofreighter or KC-97 tanker varient
McDonnell Douglas F-4 Phantom II

source, photographer: Brian Lockett

Vought F-8 Crusader
North American T-39 Sabreliner
North American RA-5C Vigilante tail number 156640

source, photographer: Brian Lockett

Boeing B-29 Superfortress

source, photographer: Brian Lockett

General Dynamics F-111B tail number 152715

source, photographer: Brian Lockett

Grumann A-6 Intruder
Douglas R4D-8 (Super DC-3)
Grumann A-6 Intruder

No C-130 appears in the photo included in the question, though one may appear elsewhere near the coordinates linked.

Notes:

1 and 11 are not C-47 Skytrain. They are longer and have a square tail which is typically for the Super DC3 / R4D-8
3 is longer from the wing root to the nose than the same measurement on 8, supporting that 3 is not a B-29.
Moreover, in the photo of 7,  aircraft 3 appears in the background which clearly shows engine nacelles like those of the B-50 or C-97 series.
The same photo shows a fuselage rising higher above the wing than a B-50, which is consistent with a C-97 variant.
5 measures nearer the 54 ft in length of an F-8, versus the 46 ft in length of an F-7, supporting that it is an F-8


Are NACA airfoils used in modern aircraft design?

Just three data points: The tail surfaces of the Pilatus PC-12 still use the venerable NACA 0012, even though a better alternative (from the Wortmann FX 71 L series) was proposed. It did not help that the Wortmann airfoil is used on many small airplanes, has more lift and less drag and an abundance of data exists on it: The (mainly British) engineers at Pilatus were too conservative to use anything newer than an airfoil from the 1920s.

Pilatus PC-12 (picture source).

The wing of the Dornier Seastar, designed by a group of old Dornier engineers in the early 1980s, used the same airfoils as the venerable Do-17 of the 1930s, namely the NACA 23012. Later flight tests showed the need to add a leading edge droop on the outer wing, a modification that cost several knots in top speed and would have been entirely avoidable with better airfoils and/or the use of washout.

Dornier Seastar. Picture by Rschider (own work).

The excellent Polish aerobatic glider Swift S-1 uses indeed a NACA 6-digit airfoil, the $64_1412$. As Jerzy Makula explained to me, it gives excellent snap roll and spin control, and when flying the prototype, I could control the exit direction from a spin within ±15° with very little practice. Jerzy simply took what had worked before.

Swift S-1. Picture by TSRL (own work).

Generally, small companies or experimental airplane builders still rely sometimes on the NACA series, but in general better alternatives exist. Big companies use custom-made airfoils, helped by computer codes which model not only the two-dimensional flow around the isolated airfoil, but can optimize the specific wing section by including the influence of engine nacelles, pylons and the fuselage. Well-designed wing roots do not use one single airfoil, but a three-dimensional shape which minimizes interference drag.

This is true even for glider companies. While Wolf Lemke used his own creations for the early LS series of gliders on the basis of their good looks (and with good success), todays gliders are designed in the computer, helped by university departments which relish the chance to let students work on real-world designs.


What is the function of the protruding outlet on the Trent XWB?

That is the drain mast and breather outlet combined. There's some discussion about this in airliners.net (not the same engine, but I sure they are similar):

The exhaust from the air/oil separator goes out here. Usually hot air, but when the engine is running at idle you can see smoke coming out. This is engine oil that has got past the seals. The smoke stops as the engine speeds up, the air pressure increases, and the seals work properly.
Also in the main body of the mast are four holes. These are tell tale drains from various parts of the gearbox. They drain out the cavity between the accessories (starter, fuel pump, hyd pump etc.) and the gearbox.

You can see the drain in the cutaway of Trent 500 here. Here's a closeup of the part in question:

Trent XWB drain; image from a380.boards.net; credited to Part of the Trent XWB by JKKW, on Flickr


What are the procedures to get a revoked mechanics certificate reinstated?

I think you've to apply for a certificate again after the required period and take the tests again. From 14 CFR §65.11 Application and issue:

(d) Unless the order of revocation provides otherwise—
(2) A person whose mechanic or repairman certificate is revoked may not apply for either of those kinds of certificates for 1 year after the date of revocation.

In your case, you have to wait for 1 year after the final conviction to apply. From 14 CFR §65.12 Offenses involving alcohol or drugs:

(a) A conviction for the violation of any Federal or state statute relating to the growing, processing, manufacture, sale, disposition, possession, transportation, or importation of narcotic drugs, marihuana, or depressant or stimulant drugs or substances is grounds for—
(1) Denial of an application for any certificate or rating issued under this part for a period of up to 1 year after the date of final conviction;


What should be my basis for selecting an airfoil?

For trainer aircraft, the major design driver in wing profile selection is stalling behaviour. Ample warning, docile & progressive stall, no sudden surprises. Stall behaviour must be demonstrated during certification. From Torenbeek:

  The stall should preferably be characterized by a distinct and initially uncontrollable nose-down pitching motion, and during recovery to level flight it must be possible to prevent angles of roll and yaw of more than approximately 15 degrees (light aircraft)..

The NACA 4- and 5-series have been around for a while and there has been much experience with the application of them. Again from Torenbeek, fig 7-12:

Four-digit

  The NACA four-digit wing sections ... are by no means low-drag profiles, (but)
  the drag increase with lift is fairly gradual. The cambered sections have rel- atively high maximum lift and the stalling is fairly docile.

  In view of the gradual changes in drag and pitching moment with 11ft, the 4-digit sections are frequently used for light trainers, which often fly in different conditions.

Five-digit

  The NACA 5-digit wing sections ... have the highest maximum lift of the standard NACA sections, but the stalling behavior is not particularly favorable and rather sensitive to scale effects.

This can be seen in the $C_l$-$\alpha$ curve B above, which drops off suddenly and dramatically after max $C_l$

NASA report CR-1646 has more information on the stalling behaviour of NACA profiles.


Can any military aircraft (only fighter jets not the military cargo ones) be stopped using Arresting Gear technique?

In order to engage the usual arresting gear (cables) on an aircraft carrier,
it helps to have a tail hook.

There are other forms of arresting gear that do not require a tail hook.
Presumably the main limitations on an aircraft using them are the size, weight,
and landing speed of the aircraft.
These devices do not seem to be designed for as frequent use as
the arresting cables of a carrier.

Followup: As I found out on looking into this further,
many (most? all?) present-day land-based fighter jets,
not just Navy or Marines jets, have tail hooks as well.
However, at least according to this blog entry,
tail hooks of the types of aircraft used by the US Air Force (and some other
air forces) are not designed to work with aircraft carrier arresting cables
but only with land-based systems (which suspend the cables higher than the
aircraft carrier systems do).

As mentioned in a comment (and in the Wikipedia article on "Arresting gear" linked above), barrier nets can serve as arresting gear.
Various publications (for example the Supplement Alaska, pp. 10–11,
accessed 22-Jan-2015)
list numerous kinds of gear, including cables designed to engage tail hooks, woven straps designed to be torn by tail hooks (one-time use only!), nets designed to engage struts, nets designed to engage wings, nets combined with cables, and engineered material arresting systems (EMAS) that absorb energy as they are crushed under the wheels of the aircraft. I have not yet found any citations of EMAS being used by military aircraft, but its main limitation of seems to be landing speed rather than aircraft weight or size, as an FAA fact sheet on EMAS dated December 12, 2014 credits these systems with stopping nine aircraft that overran runways in separate incidents, including a Boeing 747, an MD-11, and an Airbus A320.


How can a pilot become established on the KBIV, ILS or LOC Rwy 26 Approach?

To answer question #1, you are not allowed to use this approach when arriving to the PMM VOR from radial degree numbers 004 ascending to 091. This means that you can not fly in to PMM from the Northish, Northeast, or East. This is probably to avoid conflict with the major congested area of Grand Rapids and its associated airport’s Class B airspace. Also, V170 is no longer an active victor airway. And, PMM R-29 is unusable for VOR only navigation. However, this does not preclude using this approach for local flights and radar vectoring where an arrival would not be necessary.
To answer question #2, the course reversal at JAVPO is not mandatory. It is a Holding pattern in lieu of procedure turns. JAVPO is the Intermediate Fix for the approach. You can use JAVPO or its associated intermediate leg as a gate for a straight-in approach on the IAP. Just state your intentions and get clearance to maintain spacing and separation.
Wbeard52 has given a great acronym to remember when a procedure turn is not required. Another one to remember is the one derived from the FAA‘s list of situations not requiring a procedure turn included in the Instrument Flying Handbook. It is the acronym taught to prepare for the FAA written knowledge test and the practical checkride.
S.H.A.R.P.T.T.

Straight in approaches
Hold in lieu of procedure turns
Arc approaches
Radar vectoring
No Pt noted on the approach
Teardrop course reversal approaches
Timed (start) approaches

One point to note is that a procedure turn should be planned anytime the angle inbound to join the approach will result in a turn of greater than 90°. This means that flying from PMM on the 033 radial direct to JAVPO without vectoring would result in a course reversal. However, you could hold on the published hold at PMM to get set up for the approach. This would necessitate holding at a traditionally very busy (aircraft dense) fix, though. Probably something both you and ATC want to avoid for a GA aircraft if possible.


The MD-11 has one of the highest approach speeds, which is comparable to the 747-400 (Boeing), while having higher wing loading: 806 vs. 756 kg/m$^2$. In other words, the MD-11's wing is small, so flaps 50 is not an overkill.

The standard MD-11 landing flaps are either 35 or 50 depending on the weight, altitude, available stopping distance, etc.

Aircraft manufacturers don't usually go for overkill items. The bigger the flaps deflection the more loads and stresses there will be, and the stronger and heavier the flaps and wing support need to be made.

Further, the MD-11's flaps arrangement is covered in a NASA study, from which:

  Because of high wing sweep, the slant angle on the inboard closure rib of the outboard flap is about 30°. When the flaps deploy, the slanted inboard rib exposes a forward-facing surface. The same out-of-streamline angle applies to the aft portion of the hinge fairings when the flap is deployed. (See fig. 1.24.) Both of these features degrade flap lift performance and cause drag. [emphasis added]

If McDonnell Douglas had went for an all-new wing for the MD-11, and not just adapt the DC-10's, it would have doubled the development cost, see: How much does it cost to design a jetliner's wing?


Can aviation HF radios receive while transmitting?

In general, the HF radios in aviation work in simplex mode.

According to the Annex 10 to the Convention on International Civil Aviation- Aeronautical Telecommunications Volume V Aeronautical Radio Frequency Spectrum Utilization Chapter 3,

  3.1.1 In the aeronautical mobile service, single channel simplex shall be used in radiotelephone communications utilizing radio frequencies below 30 MHz in the bands allocated exclusively to the aeronautical mobile (R) service.

Though some aviation radios are capable of semi-duplex operation, virtually all aviation services operate on simplex.

I have no idea why the operator was stepping on the aircraft's transmission though.


The fuselage, and any other surfaces that air is flowing over, will contribute to lift.  This was one of my interview questions when I joined Airbus in 2003!


Why do these safety instructions have a ruler on them?

This looks like just a courtesy tool on the safety card, but doesn't actually have a requirement or purpose. Previous versions of their safety card did not have this courtesy tool.

(Image Source: aviationfreaks.freeforums.org)


Why Air France 447 could not reduce angle of attack?

I just finished reading this article and couldn't understand why in 3
  minutes and 30 seconds even though there was no reliable speed data,
  pilot could not level the plane?

If you look at this video by the French accident investigation bureau (BEA) you can see what happened.

The problem started when the speed indicators failed temporarily because of icing of the pitot tubes. The aircraft was flying through the intertropical convergence zone (ITCS) where severe thunderstorm activity can build up to high altitudes.

Instead of maintaining attitude and thrust setting, which is a normal procedure when speed indication is lost, the pilot flying (PF) brought the nose up. The aircraft started to climb but at the same time lost a lot of speed (trading kinetic energy for potential energy). Eventually the airspeed dropped so far that the aircraft stalled. By the time the aircraft entered the stall, the pitot tubes where de-iced and all speed indicators were working again. From the moment the aircraft stalled it started to sink. The PF tried to maintain a nose-up attitude, eventually using full aft stick. We can only guess to the reason why; it is likely that he was disoriented and had no confidence in the instruments after the failure. Yet it goes against basic flying instincts to pull the nose up in a stall.

The aircraft is naturally stable and will automatically drop its nose in case of a stall so it took some effort by the PF to keep the nose up. The horizontal tailplane then stalled as well which removed a lot of the nose-down tendency. The result was that the aircraft was in a nose-up attitude for the most part of the descent.

The angle of attack remained therefore too high and the aerodynamic stall persisted all the way down. If the crew would have brought the nose down they would have increased the speed, lowered the angle of attack and recovered from the stall. Once recovered from stall they could then level off the plane.

It may have contributed to the confusion of the crew that the airspeed was below 60 knots during portions of the descent. As they accelerated through 60 knots, the stall warning re-appeared.

The stall indicator systems makes use of alpha vanes which need some airflow over them to work. By inhibiting the stall warning below 60 knots the system is prevent from giving nuisance warnings on the ground. Such a speed is not normally encountered during flight, even not during a stall.

Another contribution to the accident may be that the pilot-not-flying (PNF) cannot see what stick inputs are given by the pilot flying. If it would have been in a different aircraft with coupled yokes, the PNF may have realized what was going on.

  Isn't the angle of attack reported by a gravity based tool like in
  off-road vehicles?

The angle of attack is the angle between the chord of the wing and the incoming airflow. It is not related to gravity.

  Summed up Question: When it's unclear what is happening with the
  aircraft, isn't it safer to put it in level position and medium speed?
  (Sorry for rudimentry language here)

Initially only the speed indicator failed. If the crew would have remained at the same attitude and power setting the aircraft would not have stalled. That is the standard procedure in such a case ("thrust and attitude")  That may not have been the proper reaction in this case. The aircraft was encountering severe turbulence and the fastest way out may have been to climb. But after the stall warning sounded all speed indicators were back to normal and the aircraft was flyable.


Like everything else, air will be accelerated either upwards or downwards if a force is applied to it. The aircraft's wing applies a downward force to the air mass thus accelerating it in that direction. However, nothing applies an upward force to that mass of air, so it can be assumed it will not climb back up.
(I am neglecting the formation of vortexes and possible differences in air density)

The velocity of the mass of air will be reduced by friction with and the inertia of the surrounding air until it comes to rest.

What you call the "normal flow path" of the air is it simply being still before an aircraft flies through it.


What are the reasons for autopilot restrictions on instrument approaches?

It's the fact the autopilot works more accurately than a pilot which is actually the cause of the restriction.

The decision to restrict the use of the autopilot usually comes from the certification agency after the ILS inspection flight detected glideslope erratic variations or reversals. The false signals are likely due to interference from the environment or the nearby activities with the runway equipment.

Flight inspection volume

The ILS volume surveyed by certification agencies using ICAO recommendations is located below a 5.25° angle. It means G/S indications are checked and expected to be correct only below this angle.

Source

This is why G/S are usually intercepted from below unless specific procedures are in place and extra care is given to validate G/S indications.

Anomalies in flight inspection volume

However there can be false and reversed guidance areas within this volume. They are discovered when the ILS is commissioned and flight tested by the certification agency. Example of glideslope reversal during an inspection on the nominal slope:

(Source, page 15-97)

In these areas, the ILS signal may vary quickly and if the autopilot were active it could react to the variations, while a pilot will likely not notice the interference, or will disregard it unless it follows a trend for a few seconds. A pilot with a Vertical Situation Display can confirm the ILS error visually.

A reversal, which is a guidance given in the wrong direction, can lead to a serious incident or an accident, due to autopilot quick reaction time. When such reversals are discovered during the inspection flight, autopilot approaches are not authorized, or forbidden during the final segment where the consequences can be the worst.

Consequences of a reversal during autopilot approach

Using the erroneous signal from the ILS may divert the aircraft from the approach path. Being below the glideslope close to the threshold is indeed not desirable, especially for a jet aircraft for which the thrust increase required to recover the lost altitude cannot be obtained instantaneously.

Suddenly jumping higher is also dangerous. It leads to a loss of airspeed, and possibly to an unrecoverable stall. Below is an example of autopilot reaction to a reversal. While it didn't happen in the certified volume of the ILS, the principle is exactly the one found in any reversal.

Some explanation about the context it happened

It was believed for a long time ILS radio signals for the glideslope contain false guidance at angles multiple of the nominal approach slope (e.g. 6° and 9° for a 3° G/S), but it was also taken for certain these false glideslopes were not reversals and would anyway guide the aircraft to the threshold, at a different descent rate (which would be enough to warn the crew about them following a wrong glide angle).

However G/S reversals, especially after 9° has been observed later (2011-2013), for some types of ILS antennas, without a full understanding of the reasons. Among these cases (source ICAO):

Schiphol Airport, The Netherlands, 2011, KLM, Embraer E190
Murcia Airport, Spain, 2011, Ryanair, Boeing 737-800
Charles de Gaulle Airport, France, 2012, Air France, A340 (BEA report)
Treviso Airport, Italy, 2013, Ryanair, Boeing 737-800
Eindhoven Airport, Netherlands, 2013, Ryanair, Boeing 737-800.

Eindhoven serious incident, May 2013

A B738 on autopilot was flying a non stabilized approach where the G/S had been captured from above. When reaching the 9° glideslope area, at 0.85 NM from the threshold, the aircraft suddenly pitched up to 24° and climbed from 400 to 1,000 ft. Airspeed plummeted to 100 kt, the stick shaker activated:

Source. Original source: Dutch Safety Board report

From the investigation done by the Dutch agency, it appears the actual guidance provided around 6° and 9° is completely reversed:

Source

As a partial mitigation measure, Boeing changed the Flight Control Computer software to limit the pitch up rate in G/S mode. The BEA also recommended manufacturers would prevent the capture of the G/S by an aircraft not on the published glidepath.


Is there an in-flight built-in-test in an airplane?

The thing that separates a BIT/BITE (E=Equipment) from continuous fault monitoring is that the continuous fault monitoring simply responds to exceedances of various paramters or values outside of specified limits in real time as they happen (say where an analog voltage signal of a device drops below a minimum of X or exceeds a maximum of Y), whereas a BIT/BITE test is a specific routine where simulated fault signals are injected into a circuit to see if a fault monitor is doing its job.

BIT or BITE tests of electronic controllers can be categorized into three types:

Start Up BIT: Most common.  A test routine automatically run on power up of the controller.
Initiated BIT: Controllers may have a manually initiated BIT/BITE that can be run any time, but this is usually triggered by a button on the controller itself in the avionics compartment, or through a maintenance access portal in the aircraft maintenance diagnostic system, and usually doesn't have a flight crew initiated facility (but may in some cases).  These are normally intended for troubleshooting.
Continuous BIT: A controller may run an internal self test routine on a continuous cycle while powered up, where a controller has fault detection circuits that can't be allowed to have dormant failures, even for the duration of the flight.


How to literally take the wing off a single engine Beechcraft-style airplane?

A normal collection of combination wrenches and sockets, in inches, plus pliers, wire cutters etc, the ole' help along hammer, small bolt cutters for cutting control cable, etc. should do the trick.  Maybe sawhorses to rest the fuselage and wing on.  If the wings are individually removable, they'll be attached with two big bolts or two rows of smaller bolts, just inside the cabin under the seats, and a singe bolt at the back on each side.

The main thing to take care with is there'll be a hydraulic line running out the wing root to the landing gear leg with red hydraulic fluid (similar to ATF fluid) in it for that side's brake, so you should disconnect at each end and drain the brake line first, and there is probably a fuel tank so you need to make sure that is drained and be ready to catch fuel when you disconnect the fuel line connection at the fuselage.   If it's been sitting there for years the fuel is probably all gone but best be ready just in case.  Bring along a fire extinguisher while you're at it.

It's not much different than cutting up a car except the metal is easier to hack at if you want to take the sawzall to it.


Is there a legal minimum stop time between 2 legs?

Well, in some cases, zero.

In Australia, for a long time only two airlines (Ansett and TAA) were allowed to fly between capital cities. To work around this, East-West Airlines practiced a touch-and-go at Albury, half way between Melbourne and Sydney. Legally, these we considered separate legs (at least for some time).


Could TCAS be overwhelmed by multiple conflicting traffic and "give up"?

From my general knowledge about TCAS (that is, not from actual simulations of such scenarios), I'd say that yes, it can be overwhelmed, but not in the sense that it will give up.

First, TCAS can demand a very limited range of resolution advisories (RAs). They are only vertical. The standard "Climb" or "Descend" RA assume the rate 1500-2000 fpm. TCAS can ask to increase it to up to 4400 fpm. (Or it can ask not to manoeuvre). In most installations, it will also not produce some RAs depending on the aircraft configuration; for example, it will not ask to climb at all if the airplane has flaps down past certain point.

Second, TCAS doesn't think too strategically. It can handle many targets ("intruders"), but in the end it will sort them according to their severity (primarily using the time-to-encounter factor) and will handle the most immediate ones in RAs.

It may well happen that after a short time, another intruder will become more severe. TCAS will then recalculate RA accordingly. (It takes into account the current climb rate and is generally reluctant to change the direction or even to choose a so called "crossing" RA, where the aircraft must cross the current path of the intruder, but it will do that if it determines this necessary. It also takes into account the typical (but clearly defined) pilot's reaction to the first and subsequent RAs).

So, at each point of time TCAS will "try its best" to handle immediate threats. It will (generally) not demand impossible manoeuvres nor superhuman abilities: all it can demand is known and accounted for. Yet, in theory I bet it is possible to create a scenario where TCAS would lead to very close encounters, or will select a sub-optimal strategy - even if we assume that all the aircraft obey their RAs precisely, which in itself is not given. In aviation, the engineers (so far) generally favour clear deterministic algorithms over something very clever but unpredictable and hard-to-test.


Your choices:

a- prevent upfloat: droop is the reverse of upfloat. Upfloat is useful in reducing adverse yaw.
b- correct adverse yaw: no, upfloat does that.
c- get control feel: yes there might be some increased aeroforce feel gradient around neutral. Around zero deflection it takes a little while before the aerogradient picks up, creating very light forces in an area where good force feedback is important. Droop helps to reduce this, since both ailerons are sticking in the wind already.
d- compensate drag: no, droop creates drag.


How do symmetrical airfoils generate lift?

By using a non-zero angle of attack.  When the trailing edge is pointed downwards, and assuming the airstream leaves the trailing edge smoothly, the exiting airstream is deflected downwards.  This causes lift via conservation of momentum.  Increasing the angle of attack will increase your lift until such time as the airstream over the trailing edge becomes non-smooth.  (When this happens, you're close to stalling.)

(Image from this page, which unfortunately appears to be down)

As you can see from the above graph, a symmetric airfoil at zero angle of attack generates no lift;  see this site from NASA as well as the above Wikipedia page.


What Oil thickness is used for the geared turbofan jet engine gearbox

The more regular specification for such oils is given for the viscosity in centistokes versus temperature, as an example the Mobil Jet™ Oil 387 lubricant that can be used on Pratt & Whitney PurePower® Geared Turbofan™ PW1900G engines has a viscosity of about 5 cSt at 100°C, and about 25cSt at 40°C

Other parameters are extremely important such as the flash point temperature, the fire point temperature and the autogenous ignition temperature

Also the Total Acid Number is an important parameter for engines oil.

Please refer to the following website for more details about above mentioned oil specifications.

https://www.exxonmobil.com/english-US/Aviation/pds/GLXXMobil-Jet-Oil-387


Is deicing fluid harmful to the environment?

The main component of deicing fluid is either Ethylene Glycol (EG, toxic) or Propylene Glycol (PG, non-toxic) (source) and depending on the category applied different amounts are used annually.

There have been studies of the environmental impact of deicing fluid, which basically states:

In water, EG is not persistent and biodegrades aerobically and anerobically.
In air, EG is not readily volatile and its atmospheric half-life is approximately 1 day
In soil EG is also not persistent and biodegrades anerobically in about 1 day
EG is disposed of and treated at standard wastewater plants

(I think the above comments also apply to PG, but somebody will have to confirm that since I can't find anything that mentions it).

PG is non-toxic and is used in quite a few products that you use every day, from pharmaceuticals to food additives and moisturizers. I can't confirm but one of the linked articles says that most of the DI fluid used in the US is PG based, which I would believe, but can't source.

And from the article quoting an EPA Report 821-R-00-0016, January 2000, Revised August 2000,

  Although EPA does not use such a system, the
  U.S. Fish and Wildlife Service Classification
  System for Acute Exposures defines ‘relatively
  harmless’ as any chemical with an LC50 above
  1,000 mg/L. The test results … indicate that
  ethylene glycol and propylene glycol may be
  classified as ‘relatively harmless,’as defined by
  the U.S. Fish and Wildlife Service.

There is also one manufacturer using 1,3-propanediol which is a by-product of corn fermentation and should be relatively minor as far as environmental impact.

There is also considerable movement in airports to "go green" and recover used deicing fluid, especially considering that a larger aircraft can take more than 1000 gallons of diluted deicing solution at the rate of up to $12/gallon, quite a bit of which runs off the aircraft and onto the ground. In fact, the EPA has mandated that new airports in cold climates recover 60% of DI fluid.

Edit

It may be important to note that the point of DI fluid is to keep the snow/ice off the aircraft until it leaves the ground, not assist in flight into known ice. Depending on the fluid applied, they usually only stay on until the aircraft reaches about 100kts. This means that most of the applied DI fluid is going to end up in the airports wastewater system because most will run off the aircraft on the ramp/apron, not spread around the countryside as the aircraft flies around.


What lights does the Cessna 172 light rheostat control?

This depends more on the radios installed than the plane its self, older era planes may have had King radios with analog numeric readouts. These radios are generally back lit and controlled by what ever rheostat controls the panel those radios generally look like this

(source)

later planes may have had digital readouts which in some cases had another control to dim the intensity. This is often because in a sense the lights are always on you may need to control them with out turning on or dimming the panel. As a matter of fact you generally want them to work opposite, during the day when the panel is dim or off you want the radio lights to be brightest they would then be dimmed in the evening as you bring the panel lights on. Those radios often looked like this,

(source)

The dim function may appear on units like the DME and Auto Pilot if they are similarly lit.

Its been a while since I have night flown with one but if memory servers the newer GPS units like the GNS430/540 have backlit buttons that come on when the panel lights are activated. These units also tend to have separate ways to control the screen brightness/contrast

(source)

You may have more luck referencing the manuals for the radios them selves than the POH for the plane. You should design for the types of radios you are putting in (looks wise)


In metric:

1 milibar is approximately equal to 30 feet.  This calculation is therefore also approximate but is good for airfield elevations to several hundred feet since we round to the nearest millibar.

Divide the airfield altitude in feet by 30 to get the number of millibars above MSL. Add this to the QFE to get QNH or subtract it from QNH to get QFE.

For example, the airfield elevation is 200 feet.  Dividing by 30 gives us 6.66r.  The QFE is 1023. Add 6.66 to get 1029.66 and round up to 1030 millibars, which is the QNH.

  In imperial:

1 inch mercury is approximately equal to 900 feet.  This calculation is therefore also approximate but is good for airfield elevations to several hundred feet since we round to the nearest hundredth inches.

Divide the airfield altitude in feet by 900 to get the number of inches above MSL. Add this to the QFE to get QNH or subtract it from QNH to get QFE.

For example, the airfield elevation is 300 feet.  Diving by 900 gives us 0.33r.  The QFE is 30.12. Add 0.33 to get 30.45 which is the QNH.

If the airfield elevation is below sea level, subtract rather than add and vice versa.


Can I apply for a commercial-utility licence for an auto-gyro?

Really this is a moot point...

14 CFR 91.319 (a) states:

  (a) No person may operate an aircraft that has an experimental certificate—
     (1) For other than the purpose for which the certificate was issued; or
     (2) Carrying persons or property for compensation or hire.

And again (e) states:

  (e) No person may operate an aircraft that is issued an experimental certificate under§ 21.191(i) of this chapter for compensation or hire, except a person may operate an aircraft issued an experimental certificate under § 21.191(i)(1) for compensation or hire to—
     (1) Tow a glider that is a light-sport aircraft or unpowered ultralight vehicle in accordance with§ 91.309; or
     (2) Conduct flight training in an aircraft which that person provides prior to January 31, 2010.

21.191 (i) is in reference to operating light-sport aircraft and how it obtains an experimental certificate.

There are very few auto-gyros that are factory built and certified, and none that I can find that are currently being built.

Anything you build in your home (home-built) needs to pass certain FAA inspections before it is issued an airworthiness certificate and/or experimental certificate. All home-builts are experimental since they are not built under the manufacturers quality control system. Either way, the FAA certifies that you build it to a safe standard and a standard in which the manufacturer intended it to fly. Being used for a commercial purpose, even if that were possible (which it is not) would not change the certification process for that aircraft. It would not require you to abide by any different rules or build standards. That is implying that personal aircraft would be built to a lower safety standard than commercial ones, which isn't the case.


What's the thrust coefficient for a convergent nozzle?

It’s exactly the same equation, but now the throat is at the exit. So, Ae = A*, and so the areas disappear from the last term.


Flexshafts are used on a lot of flap systems to interconnect an array of screwjacks.  They are more or less aerospace versions of weedeater shafts, inside a hydraulic line style casing (typically stainless braid over a teflon liner).  They are used because the envelope and clearance requirements are much easier to meet than with solid shafts with angle drives and gearboxes.  You can route them through very tight spaces and around gentle corners without having to maintain clearances to adjacent parts; you just have to keep the flexshaft housings from chafing on adjacent parts, like hydraulic lines.

Flexshafts aren't meant to take high torque like solid drive shafts and are normally used in high RPM low torque applications.  Or better to say that if you want to use a flexshaft, you design your drive system to run at high speed/low torque.  A drive line might be designed to run at 500-1000 rpm with solid shafts and a moderate gear reduction at the actuators, whereas a flexshaft will run at 2 or 3000 rpm at much less torque, but with a much higher gear reduction in the actuator to get the same output force result.

Flap system flexshafts as used on CRJ200s and Embraer 145s will only have to sustain a little less than 100 inch pounds of torque at operating load, while producing several thousand pounds of force at the end of each screw jack thanks to the gear reductions in the actuators.  You get some torsional displacement, or wind-up twist, from one end of a drive line to the other, maybe 1/3rd of a turn, but with the high speed and large number of revolutions (say 800 to 1000 turns) to cover an operating range, a third of a turn of wind-up doesn't have a major effect on position sensing, so synchronization isn't a problem.

It'd be the same deal on a 747 nose door.  The flexshaft connecting the door actuators runs at a high enough speed so that synchronization down to a fraction of a turn is not really necessary because each turn is a very small part of the total motion.  Cascade thrust reversers on the CF-34 engine are also run by screwjacks interconnected by flexshafts; same thing there.

The big downside to flexshafts if used in exposed areas is sensitivity to contamination through imperfectly sealed connections.  Also the carbon steel wire windings tend to suffer from fatigue where they are crimped at the terminals.  There is a lot of back and forth flex as they spin.  They usually start to break down as individual strands fracture, and the bundle swells out and jams in the casing or sometimes lets go completely.


What exactly is considered "instrument time" for an instrument rating?

I think you are conflating two different things. Most IFR rated pilots have very little actual instrument time. Even airline pilots who fly in all kinds of weather have a low percentage of their time in the clouds. A lot of it has to do with where they fly—at over 30,000' they are often above the clouds. I would imagine that it varies a lot with the type of flying that the commercial pilot does. A freight hauler in the Northeast probably has a lot more instrument time than one in Arizona. Likewise, someone who flies their small aircraft a lot on business might have relatively more actual instrument time simply because they will be flying in the weather rather than above it.

If you look at the instrument requirements in CFR Part 61, the training requirements for the Instrument say "…hours of instrument training using a view-limiting device…". So it is possible to get your instrument rating with 40 hours of flying "under the hood" and never fly in actual instrument conditions. (You can also get some hours in a flight simulator.)  And when you take your practical test for these ratings, you will be flying under the hood and not in actual instrument conditions.

The same language is used in the Commercial rating as well. In fact, you could have a CFI who has never flown in actual instrument conditions teach you how to fly IFR!

To get an instrument rating you need 40 hours of hood time. Only 15 hours of this is required to be with an instructor. Lots of people save money on their rating by flying with a pilot friend or fellow student.

Once you have your instrument rating, you need to maintain currency by flying 6 approaches, holding patterns, and tracking courses in actual instrument conditions or with a view-limiting device. If you listen to the radio on a nice weekend, you will hear lots of pilots requesting practice approaches to maintain currency. Usually they are flying with a friend rather than an instructor.


Why would a C150 tachometer bounce so much that the needle fell off?

Cessna 150s have a mechanical tachometer driven by a mechanical tach drive cable geared to the engine.

The tach needle is moved by sensing spinning magnets driven by the tach cable.

They do wear out over time and yours has reached the end of its life.


When an aircraft is descending, does any lift act on it? If yes, how?

You seem to be confusing angle of attack and pitch angle. The pitch refers the orientation of the aircraft: where is the nose pointing? The angle of attack is the angle of the wings relative to the incoming air stream. Both can take on any value independent of each other. For example, one could imagine an aircraft falling straight down, but wings level. The pitch angle is then zero, but the angle of attack is 90 degrees!

Similarly, the pitch angle can be negative for a continuous steady state descent (and often is for a steep descent). However, you correctly identify that an aircraft on approach generally does not go into a freefall. The lift acting on the airplane is still (approximately) the same. A positive angle of attack is thus still required. As a result, the aircraft will be descending even steeper than where the nose is pointing, resulting in a positive angle of attack (the angle between the pitch vector and the even steeper velocity vector).


Would a slotted flap still work if the prop is located mid wing between the wing and flap?

Yes.  Inserting a prop aft of the wing and forward of the flap would not reduce the flap's effectiveness.  If anything, the stronger, more concentrated propwash would make the flap more effective.
The answer doesn't change for a triplane.  But off topic, I wonder about how to design a triplane that's light enough to be in the ultralight category, what advantages it would have over a biplane or monoplane.  Commercial interest in triplanes petered out eighty years ago.


Why shouldn't you inflate your life vest until you're outside the airplane?

Ethiopian Airlines Flight 961 was the flight that resulted in this addition to the safety briefing.

After being hijacked, the plane eventually crash-landed in the ocean. Many passengers died because they inflated their life jackets in the cabin, causing them to be trapped inside by the rising water.

Mayday/Air Crash Investigation S03E13 (Ocean Landing) covered the incident. The relevant clip is here (from 23 seconds in):


If the article is to be believed, the gun was probably loaded with M55A1 training rounds which are a steel core projectile with an aluminum nose-cap used for target practice as opposed to the M56 HEI or M53 API rounds which the jet would go to war with.  If it had either a full or partial magazine of the M55 ammunition, it would have had at least some firepower available to it, but I imagine the crew had resolved themselves to, if necessary to protect Washington DC, ramming their aircraft into the jetliner.  It just goes to show you how utterly unprepared this nation was for that kind of a ruse.  Its obvious that this was an anomalous and desperate measure by two very brave ANG pilots who responded to a call using whatever resources were available to them.

Post 9/11 most fighter bases in the nation keep at least two birds housed in a Hardened Aircraft Shelter (HAS) in a 'hot' condition, that is, fully fueled, 520 rounds, 2 x AIM-9s, 2 x AIM-120s, with the INS aligned and two pilots keeping watch round the clock for the alert.


How many emergency/abnormal checklists are there for a typical airliner?

How many checklists does a typical airliner have for
  unusual/abnormal/emergency scenarios?

Many. A book. The abnormal checklists usually compile to a book and it is located in the cockpit at all times.

As an example, there are 452 pages on the QRH of the Boeing 737. I counted 212 abnormal checklists using the index pages.


What is that black pod on the left wing of a TBM?

That is the front of the housing which encloses the 10" GWX70 Color Weather Radar antenna.

Here are some close up shots of a TBM depicting the weather radome.

Source: Own work

Note the lightning diverter strips:

Source: Own work

Apart from the simple fact that airborne weather radar is useful, weather radar is a common option due to the equipment requirements imposed on air carriers operating such aircraft. Specifically, in 14 CFR 135.175, the FAA generally prohibits operation without airborne weather radar equipment along routes where thunderstorm activity is forecast.

Many such single engine aircraft include the option for wing-mounted weather radar, as seen on the TBM 900 in the original question. Since weather radar requires a relatively unimpeded area for signal transmission and receipt, the antenna assembly is typically located at the nose of the aircraft, such as on most multi-engine aircraft. In aircraft with nose mounted engines, a mid or outboard wing mounted position makes sense. See the following photos depicting examples of wing mounted weather radar on a Piper PA-46-500TP Malibu Meridian and a Cessna 208B Super Cargomaster, and a nose mounted weather radar on a Beechcraft King Air B200, respectively:

Source: Own work

Source: Own work

Source: Own work

According to the TBM 900 POH, installation of the optional radar system results in a 5 KIAS decrease in maximum cruise performance and a 3 KIAS decrease in long range cruise performance. This change is due to the slight increase in drag from the radar antenna housing.


Is there any legal way to fly an inline twin-engine aircraft with a single-engine certificate?

Under United States Part 103 ultralight category, with no license or aircraft certification requirements as long as the the limitations of the category are met (dry weight, fuel capacity, single seat, and level flight maximum speed, permitted flight locations), you can do anything you like.  Whether it's safe or a good idea is up to the pilot.

Last time I checked, Part 103 requires a dry weight (with engine, no fuel, no pilot) under 254 lb, no more than 5 US gallons (though actually called out in liters) fuel capacity, and level flight speed limit of 55 kt (about 62 mph).

I can't answer relative to Canada, as their regulations concerning ultralight/microlight aircraft differ from those in the USA.