QF72: How could a disconnected autopilot change the pitch?

The A330 has a degree of automation that can't be turned off, as part of its 'fly by wire' system.

This is to say that the pilot's controls aren't directly connected to the control surfaces. They are electronic in nature, sending signals to a controller which then decides how much to move the control surfaces.

As part of that, an automatic feature is built in to prevent the aircraft from entering flight attitudes that could be dangerous. This safeguard detects unsafe flying conditions using input from the the Air Data Inertial Reference Unit (ADIRU).

In the QF 72 case, a fault in the #1 ADIRU led it to believe that the aircraft was in a 50 degree nose up attitude, so it automatically forced the nose down. Problem was... the aircraft was flying straight and level, so the result was a very sharp nose down attitude, with negative G's applied to to the cabin (and everyone in it). Anyone not strapped in was slammed into the ceiling, and then into the floor when QF72 recovered from the dive. (only to do it again)

In this case, it wasn't a faulty AOA sensor, but a faulty ADIRU, which appears to have hit an unforeseen combination of inputs... and an unfortunate combination of data and timing that led the Flight Control Primary Computer that actually runs the control surfaces to not figure out that ADIRU 1 was giving it faulty data.

A couple of months later, QF71 encountered the same problem. Fortunately, the pilot was familiar with the QF72 incident, and simply switched the FCPC from the faulty ADIRU 1 to the backup ADIRU 2 that wasn't experiencing a problem. The flight continued without incident.

So the issue wasn't really a faulty AOA sensor, it was faulty code in both the ADIRU and FCPC, which appear to have been triggered by a rare combination of ordinary circumstances.

Note that a frozen angle of attack sensor and consequent incorrect automation responses led to the crash of XL 888, on an acceptance flight when the A320 was due to be returned to Air New Zealand after a lease.


How do pilots manage to keep aircraft on centerline during taxi?

Aligning yourself in the middle of a straight taxiway isn't a problem. On the 747, if you put yourself in the middle of the taxiway as you see it beyond the nose, you'll be in good shape. If you're the captain, you can hold yourself a little left of the perceived center, but not much, because you're looking at from an eye level over 30 feet up as I remember. If the taxiway has those little metal reflectors sticking up on the centerline, you can play games trying to keep one of the nose wheels hitting them. You can just barely feel going across them. Or, since the nose gear is two wheels, you can play with getting the reflectors between the two wheels if you're really bored.

Turns on a taxiway present a bit more of a challenge insofar as keeping the center line because the nose gear is behind you, but one develops a feel for it. A 90 degree turn from a narrow taxiway onto another narrow taxiway is a little challenging, especially if the taxiway you're on T's into the one you're turning onto. All you'll see out the front window as you start the turn is grass. Also, on narrow taxiways, you can't see the taxiway out the side window from your normal sitting position.

If you need to do a 180 on a runway, you need to remember that when you first get yourself on, say, the right side of the runway, the nose gear isn't there yet, and the wing and body gear have even further to go.  You have to run yourself along the side of the runway a sufficient distance so that the airplane is aligned with the edge of the runway before you start your turn.

Personally, I found taxiing a 747 one of the more fun things in life.


What aerodynamic implications would a fictional two-pronged fuselage have?

I don't see any benefit (besides optics, but this is debatable). Compared to a single fuselage, these disadvantages exist:

More wetted surface for the same volume, so more friction drag.
Twin fuselages will obstruct the pilot's view more than one.
The two-pronged fuselage has a higher roll inertia, so it reduces agility.
Any instrumentation will be blocked at the side of the other fuselage, so you need more complex sensors and a sensor fusion algorithm.
The wake from the fuselage will affect the wing more than that of a single fuselage. One consequence will be lower maximum lift of the wing. This is compensated by forebody lift, but this lift is created in a very inefficient way.

Also, the fin in the picture is too small to provide sufficient directional stability without artificial enhancement.


What are the hurdles to overcome before purely electric commercial aircraft can fly?

The biggest problem with an all-electric-powered aircraft is the same as those plaguing all-electric cars; our current battery technology has nothing on the energy density of fossil fuels:

There's just no contest in being able to pack the energy needed to push a plane through the air into a volume and weight compatible with an airliner. Jet fuel is kerosene, which is pretty much right in between gasoline and diesel, while any battery technology we've developed can't even be accurately plotted on the scale of this graph.


What advantages and disadvantages do tri planes have?

The accepted answer is wrong.

Triplanes have all the disadvantages of biplanes, only more so. But they share their advantages as well, and the main reason to build them in WW I was roll maneuverability:

The reduced wingspan reduced roll inertia, which helps to accelerate quickly into a high roll rate. Note that roll authority changes linearly with span (if the ailerons are scaled with the span), but inertia will change with span squared.
The reduced wingspan reduced  roll damping, so the achievable maximum roll rate is higher. The maximum roll rate is reached when the aileron-commanded rolling moment equals roll damping, and roll damping is proportional to span squared.

When the Sopwith Triplane became operational early in 1917, German pilots felt at a disadvantage and Reinhold Platz at Fokker created the famous Dr.I. The next generation were biplanes again, however, and the latest Fokker creation of WW I was actually a monoplane. The high climb rate of the Triplane was caused by its low wing loading and high power-to-weight ratio and more due to the lightweight construction and the advances in engines than the triplane layout.

  What were the advantages to having more wings?

Adding a second wing creates a lightweight, stiff box girder. As for why people added even more wings, see this excellent answer.

  And, why don't countries use them today?

Because countries don't use airplanes, pilots do.


What class airspace is depicted in the magenta colored area southeast of the Lake Havasu City, Arizona AIrport?

By the legend, that should be "Class E Airspace with floor 700 ft. above surface that laterally abuts 1200ft or higher Class E Airspace"


What is the difference between the red and black box identifiers on UK airport charts?

(UK AIP GEN 2.3)

Both are holding position signs. Both reflect the physical sign color the pilot would see, below is the red J2 and black J1 as seen from the cockpit (YouTube):

Red J2

Black J1

The red is for intermediate holding positions:

  Where it is considered necessary to locate taxi-holding positions other than at runway/taxiway intersections – for example at taxiway/taxiway intersections in order to protect a priority route – the holding position should be identified by a single sign located wherever practicable on the left side of the taxiway. The sign consists of a combination of the letter designating the taxiway and a number identifying the hold position e.g. A1, A2, B2 etc. in white on a red background.

(CAP 168 Licensing of Aerodromes)


Why did Avianca have A318s with PW6000 engine?

The PW6000 was a second option for engines on the A318, not an upgrade. The rest of the A320 series at the time had options of CFM or IAE engines. The thrust was comparable to the CFM option, but the initial design had worse fuel efficiency than expected, leading some customers to switch their orders to CFM. In the end, only LAN bought A318s with the PW6000 engines, taking delivery of 15. These were later sold to Avianca Brasil, who no longer flies them.


Why wouldn't KJFK offer the ILS for 22L?

JFK ARR ILS 22L/22R DEP 22R

  If conditions dictate the use of JFK ILS RWY 22L approach, then (1) the JFK Area owns Belmont airspace 3,000' and below, (2) releases Coney airspace to LGA and LIB, (3) JFK cannot depart 31L, (4) ILS 22R unavailable if LGA departs RWY 13.

LGA ILS 22, DEP 13

  LGA Coney, Maspeth, and Whitestone climbs are available.

LGA ILS 22, DEP 13 (No Belmont)

  If conditions dictate the use of LGA ILS RWY 22 while departing RWY 13, then LGA departures are restricted to Maspeth and Coney climbs only*.

So, based on those two things, if LGA doesn't own the Belmont airspace, then Whitestone Climbs (WC) are disallowed. Therefore, when JFK uses VOR 22L, it allows LGA to use the Whitestone Climb off of runway 13, which is preferred for noise abatement.

*Personal note: this application was created prior to the addition of GLDMN, NTHNS, TNNIS RNAV SIDs which are now used instead of Maspeth and Coney.

Sources:

Previously based in LGA at a regional airline
NY Airspace Application
http://tfmlearning.faa.gov/NY_Airspace/NY_Airspace_Pkg/NY_Airspace.swf
(Only works in Firefox)


Can a drone hitting a plane be mistaken for a birdstrike?

Would one be able to tell the difference before landing?  Not likely in many scenarios.

Case 1: Bird hits windshield: blood & guts are immediately visible.  Drone hits windshield, cracks are visible but not much else.  The crew CAN immediately figure out, if they've ever see a birdstrike on the windshield, that this was something else.  (Of course, it could just be a shattered outer pane -- those do fail sometimes, not necessarily due to any collision.  Never had one go in flight, so I don't know if the sound of the pane shattering might be mistaken for a collision {or vice-versa}, or not.)

Case 2: Bird hits near the cockpit but NOT on a windshield.  Sounds like a sharp crack, like a piece of gravel hitting your automobile windshield at highway speeds.  If a drone did the same, it would probably sound pretty similar, and without the blood/guts to see (or not see), the ability to notice what's missing may not be there.

Case 3: Bird hits the engine, and it starts running poorly. Sometimes you will smell the guts cooking in the core of the engine (i.e. they get into the bleed air system & thus into the air conditioning), and that's a clear sign that your engine ate a bird.  But the bird CAN miss the core and still cause problems with the fan blades.  Most birds that miss the core are chopped up by the fan blades & the crew had no idea until after landing that anything happened, but a big enough bird can cause damage that way.  So if the engine starts running rough, hot, and with some vibration, the absence of "cooked goose" odor isn't necessarily going to drive the conclusion that the collision had to be with something other-than-a-bird.  One might suspect that a lot of damage with no smell seems unlikely to be a birdstrike, but there are cases where some engine component has failed & caused engine damage (ranging from barely noticeable up to catastrophic), and you can't really know much about causality for the engine doing what it's doing until you're on the ground.

Now, all of this assumes that the crew doesn't see the object that they hit.  Which they very well might.  Everything in that case is obviously an entirely different discussion.


What are the advantages and disadvantages of an oblique wing over a swing wing?

The oblique wing and the swing wing aim to reduce the drag over a wide range of speeds by changing the wing sweep. While the swing wing rotates a part of the wing to achieve this, the oblique wing rotates the whole wing.

The first production aircraft with variable sweep wings was the F111 Aardvark, while the most famous one is the F-14 Tomcat.

"F-14 Tomcat prototypes in flight c1972" by U.S. Navy - U.S. Navy National Museum of Naval Aviation photo No. 2011.003.301.027. Licensed under Public Domain via Commons.

However, the only full sized aircraft to be produced with an oblique or pivot wing was the NASA AD-1, which was strictly an experimental aircraft.

"AD-1 ObliqueWing 60deg 19800701" by NASA - http://www1.dfrc.nasa.gov/Gallery/Photo/AD-1/HTML/ECN-15846.html. Licensed under Public Domain via Commons.

A comparison between the two can be made like this:

Aerodynamics: The oblique wing is much more refined aerodynamically compared to the swing wing and had lesser drag. In fact the AD-1 was designed to be as close to the optimal for all the flight regimes. Also, the aircraft was designed to have an elliptical lift distribution to reduce induced drag. on the other hand, the variable geometry aircraft did not offer any significant advantages over fixed wing baseline aircraft.

However, the asymmetric stall of the oblique wing aircraft would cause problems as one side of the wing is swept forwards and the other side is swept towards the rear.

Structure: The hinge was arguably the most critical structural part in variable sweep wing aircraft. The hinge should not only have a very high reliability, but also have the capacity to bear the high aerodynamic loads.

"Tornado variable sweep wing Manching" by Sovxx - Own work. Licensed under CC BY-SA 3.0 via Commons.

In this case, the swing wing aircraft are better off compared to the oblique wing aircraft as the amount of load on the hinge is significantly lower.

For example, the oblique wing hinge has to take not only the weight of the entire aircraft wing (the swing wing aircraft typically rotate only a part of the wing), but also the entire fuel load (the amount of fuel carried in the variable part of the wing is significantly small). Also, the hinge should take the load of the control system too.

Handling and Controls: The handling of the swing wing aircraft have been brought closer to the fixed wing aircraft over time. However,the handling qualities of AD-1 was found to be poor, with unusual trim requirements and inertial coupling affecting the aircraft negatively.

For instance, the AD-1 required about 10° of bank in order to trim the aircraft with no sideslip at 60° wing sweep.The aircraft also experienced pitch-roll coupling and the associated aeroelastic effects made for unpleasant handling qualities above 45 degrees sweep.

One advantage of the oblique wing aircraft is that the center of lift and mass doesn't move as the wings are swept. This happens in the swing wing aircraft and the control system is complicated

Engine and payload In case of swing wing aircraft, the engines can be mounted in the fuselage (like F-14) or in the (fixed part of) wing itself (like B-1). In case of the oblique wing aircraft, locating the engines anywhere except the fuselage is effectively ruled out.

In case of military aircraft, use of hardpoints in the variable point of the wing is limited (for one thing, this will increase the load on the hinge). This is a much more serious problem for oblique wing aircraft as this limits the payload that could be carried.

However, the main reason for the lack of further development of oblique wing aircraft is their unusual and unpleasant control qualities.


What do these numbers above the terminal jetway mean for pilots?

That's a countdown to the Target Off-Block Time (TOBT) showing 67 minutes to go. The minus is like the T minus 5 for a rocket launch.

[TOBT is the] time that an Aircraft Operator (AO) or Ground Handler (GH) estimates that an aircraft will be ready, all doors closed, boarding bridge removed, push back vehicle available and ready to start up / push back immediately upon reception of clearance from the Tower. (...)
TOBTs will be displayed on the Stand Entry Guidance System (SEGS) for every flight at 'Actual in Block Time' (AIBT) or 75 minutes before a departure. The countdown clock is in line with the latest TOBT update. Please see Fig.2 [emphasis and link added]

gatwickairport.com

The display design will vary from airport to airport.
Since in your photograph there's no jet bridge (no actual docking), the display is mounted separately and is not used for parking guidance. Thanks to @fooot for identifying the airport, here's a press release on SEA's general implementation.
The guidance (and information) system at SEA (where jet bridges are used) uses "infrared laser and patented 3D scanning technique" to identify the plane type, distance, and orientation – unlike the older left/right parallax-based guidance.


How can I correct the heading for this navigation problem?

The correct answer is 12 degrees.  The problem is as follows:

To determine wind correction use an E6-b or similar.

Set distance off course over distance already flown.  In this case, $\frac{4.5}{45}$. The degrees to eliminate wind drift will be under the rate arrow, in this case: 6.

Then, determine how much additional correction is needed to rejoin.  In this case, $\frac{4.5}{45}$ again.  You must add 6 more degrees to the first 6 to rejoin.

The total (therefore the answer) is 12.


How much money can be saved by removing seats?

The amount of time and manpower required to remove empty seats before a flight, transport them to the plane's next destination (presumably on another aircraft), then reinstall necessary seats for the next flight with 450 passengers (instead of this flight's 300 pax) would far exceed any potential cost savings of removing them for the flight. (Oh, don't forget, the remaining 350 seats would have to follow the plane to its 3rd destination because that flight is booked full.)
The biggest issue would be getting the seats themselves moved around so they could be reinstalled at the next destination. Not every aircraft uses the same seats, the mix of seats (cattle class, business class, first class) will be different on different versions of the same model of aircraft, even those owned by the same airline, so having a stock of seats at each airport that could be installed when the outgoing pax count is higher than the incoming pax count would be impractical.


I'll tackle the "How" first - you call up Flight Service (either on the radio or on the phone after you land) and tell them you have a pilot report.  There's a standard format for pilot reports, and if you give all the information in the order it appears on that form it's faster for you and the person taking the report.
If you're filing a pilot report on the ground for conditions you encountered enroute you need to specify the (Zulu) time of your observation (or tell the briefer "20 minutes ago"). In the air it's generally assumed your report is for "now".

Pilots are requested to provide pilot reports for significant deviations from the forecast weather, or for hazardous conditions. Basically we provide them as a courtesy and service to our fellow pilots (like flashing your lights at other cars on the highway if you know there's a speed trap).

Some pilot reports you may want to file in flight are if the Winds Aloft differ from the forecast. If the forecast told you you should have a 10 knot tailwind and you actually have a 5 knot headwind that's pretty significant, and if you tell Flight Service they will pass it along to the weather forecasters and they'll factor it in to their next Winds Aloft calculation. It will also appear in the next pilot's briefing so they'll know the winds in the forecast aren't correct.
Another example is turbulence: If you're encountering continuous moderate chop at 7,000 feet but smooth air at 9,000 feet providing that information could be useful to the next pilot flying through the same area.

A classic example of a PIREP you file after you're on the ground is icing: If there was no icing in the forecast but you've encountered some you should report these conditions. If you're under ATC control you'll obviously tell them, but when you're on the ground you should call Flight Service and file a formal pilot report. Again, the information will be passed to the weather forecasters and the icing AIRMET will be updated, and your PIREP will be passed along to other folks in their briefings to keep them out of the ice.


Two- and three-wheel undercarriage in the same airplane?

The Fairchild A-10 has been designed with a lot of forethought, taking resilience against possible battle damage into account. If half of the tail is lost, the other half is sufficient to fly home. Also, if the gear cannot be lowered, the tires are still oriented the right way and stick out of the wheel wells enough so the airplane will land on them. Since the gear retracts forward, the wheels are ahead of the center of gravity in their retracted position, turning what is a tricycle undercarriage into a taildragger with gear retracted.
As reported here:

When retracted, the Thunderbolt II's main landing gear wheels remain partly exposed: During a belly landing, depending on the stores carried by the aircraft, the wheels that partially protrude from their nacelles can provide a cushion to absorb the impact with the runway; they can also reduce the risk of fire and, generally speaking, the overall damage to the fuselage.
In addition, when the gear is up, the wheels continue to guarantee the braking action, allowing the pilot to control the aircraft through differential use of the wheel brakes. That's why the MLG design is one the features that make the iconic aircraft so resilient.

Of course, it is prudent to drop all external stores before attempting this.

An A-10 Thunderbolt II sits on the runway after making an emergency landing March 25, 2008, at Edwards Air Force Base, Calif. (picture source). This view also illustrates nicely how the pulled-down wingtips will protect the ailerons from involuntary ground contact.


How does a flex takeoff increase fuel consumption compared to a TOGA takeoff?

Fuel consumption for the flight will be slightly higher when carrying out a reduced thrust takeoff.

Simply put, the flight is operated at lower, less efficient altitudes for a tiny fraction longer, so less time is spent at more efficient altitudes. It’s a rather small amount, but nonetheless measurable.

From Airbus‘ Getting to Grips with Fuel Economy:

  Compared to a full thrust take-off, flex thrust will generally increase fuel burn. The increased time at low level offsets the slight reduction in fuel flow induced by the lower thrust.

The source goes on to list typical fuel burn increases, e.g. for an A320 it’s 1kg (!) when taking off in CONF 1+F and 5kg in CONF 2.


Is an ekranoplan less efficient than a regular plane?

There are a couple of inaccurate trains of thought in the question.

  The ekranoplan uses more thrust to fly in ground effect because it has to overcome air drag which is significantly stronger due to high angle of attack required to maintain the ground effect.

All aeroplanes need to overcome air drag, which grows quadratically with airspeed. Ground effect creates more lift at a given speed, therefore requires less thrust at that speed. Or: ground effect creates more lift at a given wing area, requiring less thrust than the larger wing required for the conventional aeroplane.

  ...thicken the air cushion to the point where the ground effect is lost and the aircraft will loose altitude down to ground effect.

Thickening an air cushion cannot result in losing ground effect. The ekranoplane cannot fly out of ground effect - increasing Angle of Attack does not make much sense and altitude will auto stabilise to within ground effect, indeed at higher thrust level at higher AoA for a given speed. I believe this is what OP means, but it does not equate to ekranoplanes being less efficient than conventional aeroplanes. Ground effect creates extra lift without a drag penalty.

Whether ekranoplanes are more or less fuel efficient than standard aeroplanes is not due to the ground effect, but to the interference with the water surface, sea state, having to lift the engine out of the spray etc. Depending on the speed, they may be less efficient than ships, but the payload arrives a lot quicker.


Which countries (if any) allow beyond-line-of-sight drone use?

The current situation (November 2018) regarding beyond visual line of sight operations (BVLOS) is heterogeneous:

Overall, not allowed in Europe, but there are notable exceptions where BVLOS is explicitly regulated, see below.
Regulated in Canada
Regulated in a few countries in Asia, Africa and Latin America.
Not allowed in the US

US

UAVs fall under Part 107 operations which prevents BVLOS (107.31). Waivers can be requested, but only 27 have been granted to date (enter "107.31" in the search box).

European Union or EASA member states

EASA is the European safety agency. For EASA member states (EU and a few other countries), there are two opposite situations today:

With no surprise North European countries (Iceland, Norway, Sweden), with many isolated locations have allowed BVLOS operations early, including for delivery of goods to consumers, e.g. Aha, an online marketplace, delivers goods using drones in Iceland. Not only this is BVLOS, but it's even automated.

Many countries don't allow it but they are waiting for a EU regulation that would allow them. Actually current opinion of the EASA is it must be allowed (but more for industrial uses than for good delivery to public):

  EASA will develop standard scenarios that will make it simpler to
  obtain authorisations for well‑defined operations (such as, for
  example, linear inspections conducted in BVLOS, or crop spraying).

(Source)

In their declaration EASA mentions linear inspections, which has been actually something done in France since a long time for railways catenaries and electric grid lines.

France has kept with its pioneering role in aviation. BVLOS is regulated since 2012. A company located in Toulouse, another well known place for aviation, paved this road. As I'm not going to do their advertising, I let you read about them online, e.g. last year they were able to have a 50-km civilian flight with a 3G data link.

Switzerland

If you are asking for your home country, Switzerland, which is also an EASA member state:

LOS is required, but waivers are possible, though there are no public criteria provided, so you need to try, when you have defined all the details of your project.

As DeltaLima mentioned (maybe with a good insider knowledge) laws are rapidly evolving in the domain, as does UAV technology.

Around the World

Taken from International Commercial Drone Regulation and Drone Delivery Services by Rand Corporation:

  For countries that have drone regulations, these regulations typically
  incorporate a pilot’s license, registration of the drone, restricted
  zones, and insurance; regulation requirements vary based on such
  parameters as drone mass, population density, altitude, and use cases.

and the list of countries in 2017:

As visible there are legal possibility for BVLOS in many countries and across all continents.

Permission limits

Same document, excerpt for three countries:

For France already mentioned, we see the BVLOS is authorized up to 1 km for 2 kg+ mass, and unlimited below (but constraints like pilot license and registration still apply). Looking at the criteria for a permissive country:

Well, except height and insurance in certain cases, there is no other ones!

Future market

While B2B application have a large market, the B2C market is huge in an era of online sales and home delivery. Amazon is waiting for (experimentation in Japan), as quick food businesses do, for their delivery.


What is the best glide speed for the DC-3 with 2 engines out?

Maximum glide angle for the DC-3 with power off, both propellers feathered, gear and flaps up, no wind is computed to be 3.88 degrees. This angle will give the maximum glide range. Depending on the aircraft's weight the following numbers can be applied to give the maximum distance:
20,000 lbs. Gross Wt. IAS 92K   (MPH 106),
23,000 lbs. Gross Wt. IAS 99K   (MPH 114),
26,000 lbs. Gross Wt. IAS 104   (MPH 120),
The rate of sink at 20,000 lbs gross weight is approximately 680 feet per minute (11.3 ft per sec.) at 5,000 ft of altitude.


Why are true and indicated airspeed different?

Air pressure reduces with altitude, so while an individual molecule is striking the the aircraft at 100kt, there are fewer of them. This means there is less pressure placed on whatever surface is being struck.
The difference in indicated speed is simply one of a physical limitation with the air speed indicator - air speed indicators rely on dynamic pressure/ram air to give a readout. Because of that reduction in pressure, the readout begins to diverge from the true, physical speed as air pressure differs from the reference pressure of the gauge.
It would be possible to create an airspeed indicator which adjusts for this, in the same way as the altitude indicator does. However, as it happens, the planes flight characteristics also changes as pressure reduces in much the same way as the air speed indicator does. Because of this, for pilots, the IAS is the important speed outside of navigational purposes.
Hence, all design speeds are written in Indicated Air Speed and can be referred to at any altitude.


Why is True Altitude calculated using the difference from the QNH to 1013hPa?

Because it is preferable to work with standard atmospheric data,(ISA international standard atmosphere where at mean sea level, the temperature is 15° and the pressure is 1013hPa)

and because your navigation instruments will display your altitude with respect to a reference, on QNH setting, above the transition altitude the reference is MANDATORILY the mean sea level pressure of 1013 hPa

However it is possible to set your instrument with respect to the field elevation(QFE) so that at landing your displayed altitude is zero.

Airfield QNH is obtained by correcting a measured QFE to sea level using ISA regardless of the temperature structure of the atmosphere. As your altimeter is calibrated using ISA, it will indicate altitude correctly at the airfield reference point. At other altitudes, the indicated altitude is likely to be in error, depending on the temperature of the atmosphere.

All altimeters are based on ISA, notwithstanding instrument error, altitude readouts between aircraft will be similar, whether flying colder than ISA or at higher temperature than ISA, the most important matter is that above the transition altitude you must be on QNH ISA condition(reference:1013 hPa) to insure height separation between aircrafts.


What is the purpose of the string taped to the front of the canopy on gliders?

Yes, the yaw string on the canopy of a glider is there to show you whether or not you are coordinated, especially during turns.  It indicates the relative wind, so will be straight unless the glider is slipping or skidding, in which case it will swing to the left or right.

For those not familiar with them, here is an image that shows one:

According to Wikipedia, they are also used on other aircraft (even jet fighters and the U-2!) although they are used in almost every glider.

Now, the advantages that it has over an actual instrument installed in the panel are numerous:

It is directly in your line of sight while looking outside, so you don't have to look at the instrument panel to see if you are yawing.
It is more sensitive
It reacts faster to changes
It is cheaper
It is lighter
It doesn't require electricity (or even an electrical system on the glider)
It costs far less to maintain
It is easy to recognize when it fails (it's either there or not)


What are the costs and labour hours for converting a B767 airliner to an aerial refueling aircraft?

It's very difficult to answer this question directly, mostly because that the costs you or I would face when undertaking such an endeavour are primarily capital in nature. For a large airline (or other organisation), they'd have staff and equipment on hand already, and the price an organisation like BA or BAE pay for parts is almost certainly different to the list price.

That being said, the deal in question is notoriously bad value for money. From that source, the taxpayer will be paying around £10.5 billion for 14 Airbus A330 troop transport/tanker jets with a capital value of only about £1 billion, although the deal also includes maintenance. Although converted to military specification, the converted passenger jets will not be flying into a war zone any time soon.

Interestingly, it appears that the government itself didn't really know the answer to 'how much will this cost', even as they were signing the contract to provide new aircraft. Specifically, a critical report from the National Audit Office concluded that there was 'poor access to full cost data – the Department never gained visibility of detailed sub-contractor costs and margins for the aircraft and their modification'.

In other words, nobody knows!


What are those buttons pushed after thrust is set to max

They're starting the chronometer. This chronometer is displayed on the navigation display.

It lets them keep track of the time limit they are allowed to operate at takeoff thrust. The limit is 5 minutes normally extended to 10 with an engine failure. After this, they must reduce power to the maximum continuous thrust setting (MCT).

There is also a time limit between the setting of thrust and when the engine reaches commanded power. If it is too long, it indicates a malfunction and takeoff should be aborted.


Why were the F-35B lift fan doors changed after flight testing?

It was due to flow issues. Here's an excerpt form Air & Space Magazine

  We discovered a few things that would need to change before the
  aircraft entered production. On the X-35B’s STOVL variant, the doors
  above the lift fan had a bi-fold arrangement: They folded and slid
  outward, creating an opening for air to enter the fan. However, when
  the airplane was slowed to a hover, the air flowing across the top of
  the aircraft would not on its own make the turn into the fan
  efficiently; it needed to be guided. On the production F-35B there is
  a different arrangement: Instead of two doors sliding open, a single
  door, hinged aft, lifts up and acts like an air scoop, helping to
  funnel the air into the fan. But the new design of the lift fan cover
  created additional challenges for the two auxiliary air inlet doors
  that sit right behind it. Not all the air is channeled into the fan,
  and at higher speeds, the air that flows around its raised cover is
  turbulent, causing the open doors on the auxiliary air inlets to
  vibrate. The hinges on those doors, therefore, had to be strengthened.

You'll also note that the Auxiliary Lift Fan doors changed (bigger, hinged on outboard edges) as a result of the main door change.


Can an airliner be refueled while the APU is running?

Refueling an airliner with APU running is a perfectly normal procedure and it is done daily all around the world. The APU is located at the tail cone partially to reduce the risk of fire spreading to the fuel tanks, which are normally in the wings and center fuselage.

Some operators and authorities (not all) restrict starting and/or stopping the APU while fueling.


What is the straight-and-level altitude record for a heavier-than-air winged/lifting-body aircraft?

As of writing this, the official (as verified by FAI) "altitude in horizontal flight" category record goes to the SR-71 on 28 Jul 1976 at an altitude of 25 929 m (85 069 ft).
Second place is 24 463 m (80 259 ft) in a YF-12A, and third place is 22 670 m (74 377 ft) in a E-166 (modified Ye-152).

For more: www.fai.org


How to learn the back end of flight simulators?

The most advanced open source flight simulator is currently FlightGear. It doesn't fall too far short of its commercial brethren.

The repository is hosted on SourceForge, where you can download the entire codebase.
For documentation and discussion on how it works, see the forum and the mailing lists.

Once you have questions regarding the codebase per se, especially regarding the technical implementation rather than the business end of the simulation, they are best asked on the forums or on the main Stack Overflow site. Aviation.SE mainly deals with the flying aspects and real-life aircraft.


What modifications need to be made on an engine that normally uses AVGAS to utilize it with MOGAS?

For any certificated aircraft engine, the type certificate will specify the required fuel. If the TC specifies AVGAS, using MOGAS will require an STC for that engine.
Developing a MOGAS STC for an engine is a complicated and expensive effort, so you're realistically limited to purchasing the rights to an existing STC. If there isn't an STC for your engine, you're likely out of luck.
The two most common STCs for GA piston engines are available from EAA and Petersen Aviation. Check their web sites for a list of engines covered by their STC.
Once you purchase the STC, it will include the installation instructions outlining the necessary modifications for your engine. In many cases, it's nothing more than placards and a flight manual supplement.


How do pilots know that the switch/knob they just switched on/off actually did what it's supposed to do?

Depends on the system in question, but typically the following indications will serve as a means to verify that a system is functioning correctly.

Activation lights - some cockpit switches will illuminate when commanded by crew.  Granted this only can serve as an indication that the switch was engaged.

Indicator lights eg landing gear position lights, etc - remote switches on mechanical systems which are activated when said system are in a required positions or functioning.  The switch then can illuminate lights on an instrument panel.

Mechanical indicators eg flap position indicators - system provides either a mechanical or otherwise signal back to an indicator which mechanically moves in unison with with the system.

Information Displays - integrated flight decks and multifunction displays take inputs from similar remote mechanical, thermal, pressure and electrical inputs from aircraft systems and display either textual or graphic indications on displays.

Kinsethetic reactions - eg lowering flaps will cause the airplane  to decelerate and pitch up, landing gear actuation will cause sounds, vibrations, wind noises, etc.

Correct system function - eg autopilot mode engaged and the airplane is doing what the crew expected of the command.


Does the F-35B use its articulating rear jet nozzle for thrust vectoring?

In hovering or STOL/STOVL/VTOL flight yes it can vector its thrust but the system is not operable during conventional flight modes.  No version of the F-135 is publicly known to be capable of this.  Unlike the Harrier, F-35Bs cannot use the vertical lift system in the conventional flight regime.


What would happen if the sole pilot dies while flying an aircraft?

It has happened before that the single pilot lost consciousness while flying. What then happened is that the plane just went on until out of fuel after which it will glide down and skid to a stop (pilot survived). This is assuming there is no obstacle in the way.

Another example is the cornfield bomber, a fighter pilot eject and the plane still under power just kept going in a straight line and "landed" in a field.

A more deadly example is the helios flight 522. A mistake in the pressure regulation setting let the plane become unpressurized while climbing to cruise altitude. Both pilots lost consciousness and the plane's autopilot followed its programmed path following the waypoints and ending up in a holding patter until it ran out of fuel and crashed into the ground.

Survival depends on luck with obstacles, whether the plane is properly trimmed and which order the engines flame out in, asymmetric flame-out may result in a spin.


Why was the B-52's wet wing more susceptible to fatigue than its dry wing, and not less?

Earlier B-52s did not carry all their fuel in the fuselage. They also carried their fuel in the wings using rubber bladder-type wing tanks.

The new B52G “wet wing” was a weight savings measure which also increased the fuel capacity over the bladder-type in-wing tanks. The metal fatigue of the new wing was due to a poor structural design which was supposed to save weight.

http://www.joebaugher.com/usaf_bombers/b52_15.html

  The B-52G had a lighter structure than previous versions in order to save weight, but it carried more fuel. This meant that fatigue problems resulting from the structural flexing generated by the stresses of low-level flying and midair refuelling manifested themselves earlier in the life cycle of the airframe. This was especially the case in the region of the wing structure where most of the weight savings had been achieved by using an aluminum alloy. Fatigue cracks got so bad that stringent flying restriction had to be imposed, pending modifications. In May of 1961, a program was approved in which the wings were modified and strengthened as part of the regular IRAN schedules for the aircraft in the B-52 fleet. The project was finally completed in September of 1964.

Early B-52B,C,D fuel chart showing multiple wing tanks.


Is a hold short expected when given taxi directions to a runway?

Yes.  A taxi clearance enables you to taxi an aircraft through a controlled movement area within the terms of the clearance given by ground control.  Entering an active runway requires an explicit and separate clearance from the tower to do so.

In addition, crossing any runway which intersects your taxi path requires an explicit clearance from ground control to do so.  This clearance can be included in the original taxi clearance or a separate clearance wile your aircraft is currently taxiing.  If you reach the hold lines of an intersecting runway, you must hold short unti you are cleared to cross by ground control.


Why is pitch measured with respect to the horizon and not the ground?

Pitch is measured with respect to a plane orthogonal to the local weight¹ force, which is properly called the horizontal.

That is used because:

It is equipotential plane of the gravitational field. Moving around it won't change your potential energy.
Is always well defined.
Is smooth and locally flat (it is still a spherical surface globally, of course).
Can be measured by averaging inertial forces on board without external reference.

It is called simply horizon, presumably because looking at the horizon is the easiest way to find that plane by human senses.

Using ground, which is not flat, as reference wouldn't work. Aircraft need to fly mostly along the equipotential plane, because climbing to a higher one requires adding more energy by the engines and descending below means the aircraft accelerates and needs to dissipate (= waste) the energy. So following terrain would require quite a bit more energy than flying horizontal. Plus it would be very complicated.

¹ By weight I mean the sum of gravity and centrifugal force in the reference frame rotating with Earth.


What considerations should be taken into account for landing on gravel airstrips?

Standard soft-field landing and take-off techniques work on dirt, gravel or grass. The differences are more in ground operations, and even then they aren't really big differences: it comes down to being aware of what's around you and what condition the surface is in. That includes taxi and parking areas, not just the runway.

With gravel, the main risk is damage to the aircraft (especially the prop) or nearby people, vehicles or objects caused by gravel being thrown up by the prop. With dirt, you're more likely to have to worry about drag or even getting stuck, especially if the surface is wet.

Some specific considerations for gravel are:

If you're parked on gravel, be careful where the aircraft is pointed when you start up. You don't want to spray some unfortunate person, vehicle or building behind you. Re-position the aircraft before starting up if you have to, and you could also brush gravel away from the prop.
For the same reason, pick your runup spot carefully
Keep back pressure on the controls all the time while taxiing, to keep the prop as far away from the surface as possible. Don't feel you have to taxi in a straight line: taxi wherever the gravel is lightest and the surface is smoothest.
Open the throttle smoothly for takeoff or runups to avoid suddenly throwing up gravel

Dry, well-packed dirt usually isn't much of an issue (apart from visibility), but wet dirt - i.e. mud - is potentially tricky:

If conditions are very dry then you can throw up a lot of dust. That may not be as dangerous as spraying gravel around, but it's still unpleasant for anyone nearby and there is a safety risk if people can't see you or other aircraft/vehicles because of it.
If conditions are wet then there's a risk of getting stuck in mud. Once you're moving, try not to stop unless absolutely necessary. Consider doing a 'rolling runup' if you're confident you can do it safely (practice on tarmac first!).
Calculate your required takeoff roll carefully and know exactly where you have to abort. Mud will create a lot of drag, and you don't want to push your luck on what is most likely a short runway.
If you take off from wet dirt you'll leave ruts behind you. When the dirt dries out those will still be there, and they could be a hazard to other aircraft using the runway (some dirt becomes very hard when it dries). Try to find someone who can smooth them out after you depart.
If you do get mud on your aircraft, clean it off if at all possible before taking off. As well as decreasing performance, it could clog up pitot-static ports or otherwise affect airworthiness.


Is it legal to fly in RVSM airspace with an inoperative autopilot?

About whether or not you can fly with an inoperative autopilot, take a look at §91.180:

  §91.180   Operations within airspace designated as Reduced Vertical Separation Minimum airspace.

  (a) Except as provided in paragraph (b) of this section, no person may
  operate a civil aircraft in airspace designated as Reduced Vertical
  Separation Minimum (RVSM) airspace unless:

  The operator and the operator's aircraft comply with the minimum
  standards of appendix G of this part; and
  The operator is authorized by the Administrator or the country of
  registry to conduct such operations.

  (b) The Administrator may authorize a deviation from the requirements
  of this section.

You also can't say that your aircraft is allowed to operate in RVSM airspace:

  Section 4. RVSM Operations

  (a) Each person requesting a clearance to operate within RVSM airspace
  shall correctly annotate the flight plan filed with air traffic
  control with the status of the operator and aircraft with regard to
  RVSM approval. Each operator shall verify RVSM applicability for the
  flight planned route through the appropriate flight planning
  information sources.

  (b) No person may show, on the flight plan filed with air traffic
  control, an operator or aircraft as approved for RVSM operations, or
  operate on a route or in an area where RVSM approval is required,
  unless:

  The operator is authorized by the Administrator to perform such
  operations; and
  The aircraft has been approved and complies with the requirements
  of Section 2 of this appendix.

If it's not operational, the aircraft no longer qualities for RVSM, and therefore must be provided with 2000 feet vertical separation (each way) between other aircraft. Alternatively, ATC can refuse entry into RVSM airspace.

Regarding having the autopilot engaged, Appendix 4 of AC 91-85, Section "5. In-flight Procedures" states:

  e. An automatic altitude-control system should be operative and engaged during level cruise, except when circumstances such as the need to retrim the aircraft or turbulence require disengagement. In any event, adherence to cruise altitude should be done by reference to one of the two primary altimeters;


Do/why don't spaceplanes suffer from flutter?

Not Shuttle specific, but there are generally two ways to prevent flutter of a control surface; for a manually operated surface, you balance it to put the surface's CG at or slightly forward of its hinge line, so that motions of the parent surface have a neutral (if CG on the hinge line) or counteracting (if CG is forward of the hinge line) influence on exciting sympathetic motion in the surface (that is, if the wing flexes up, with the CG aft the surface it "trails" the motion and displaces down relative to the wing attachment, putting it on the hinge line neutralizes this effect, and putting it forward of the hinge line has the opposite effect, creating an inertial moment in the same direction as the wing motion).
If the surface is hydraulically powered using irreversible hydraulic actuators, balancing of the surface generally isn't required and flutter protection is from the rigidity of the hydraulic connection (both in holding the surface from moving, and also acting as a passive damper when unpressurized). You can usually tell an airplane with irreversible hydraulics because there are no tabs or balance horns, or offset hinge lines, and the center of gravity of the surface will be some distance aft of the hinge axis.
So jets with irreversible hydraulic controls typically have unbalanced control surfaces that depend on the hydraulic actuators themselves for flutter prevention, and may also require additional passive damper units if the number of actuators used doesn't meet the minimum damping requirements following loss of an actuator. Service backlash limits for surface hinge attachments and actuator connections (resulting in surface free play) are largely a function of maintaining the rigidity of the system for flutter resistance.
The Shuttle having hydraulically driven control surfaces, you can be sure that flutter resistance is ultimately coming from the hydraulic actuators and the stiffness of the connections and structure (I don't know if the shuttle uses dedicated flutter dampers to back up the actuators).


Is there a regulation that defines when to use QFE or QNH for landing?

AFAIK there is no EASA regulations forcing a pilot to use one or the other. The default option is to use QNH, which shall be transmitted to all aircraft:

(3) Except  when  it  is  known  that  the  aircraft  has  already  received  the  information  in  a directed transmission, an QNH altimeter setting shall be included in:
(i) the descent clearance, when first cleared to an altitude below the transition level;
(ii) the approach clearance or the clearance to enter the traffic circuit;
(iii) the taxi clearance for departing aircraft.

But there is an option to use QFE as well, and it is commonly used in some places, for example for certain operations in the UK and sometimes for military operations.

(4) A QFE altimeter setting shall be provided to aircraft on request or on a regular basis in accordance with local arrangements.

The "in accordance with local arrangements" part also incidates that EASA has left it up to the individual local authorities to decide whether or not to use QFE - so it is unlikely that EASA has a common rule for this.
Both quotes are from SERA.8015


Do aircraft use their lights to 'say hello' to each other?

Yes, it is true.  When two aircraft flying in opposite directions pass each other at night, it is quite common for one or both to briefly turn on their landings lights. This is done partially to "say hello", and also to increase situational awareness. I would guess it happens about 50% of the time.

Usually one aircraft will turn on their landing lights about 2-5 miles back and wait for the other to briefly flash their lights in response. It is not uncommon to get no response because the pilots on the other aircraft may have their heads down, and not see the other aircraft. Some pilots don't respond because they feel it is a useless practice, and can't be bothered.

When there is only 1,000' vertical separation of opposite direction, or crossing  traffic, some ATC jurisdictions might require the controller to inform the aircraft of each other's presence. In that case it is more likely that both aircraft will turn on their landing lights to be more visible to the other aircraft. There is no operational requirement to do this, but most pilots tend to go along with this practice.


Do any aircraft have liquid-cooled brakes?

A liquid heat exchanger system for brake discs, with coolant, lines, some way of transferring heat from the disc pack to the heat exchanger, that would somehow keep the entire apparatus liquid tight... yikes.  I can only imagine what a monstrosity such a design would be, even if it's technically feasible.

Brake temperature requirements don't affect gate turnaround times. 99.99% of the time you land and taxi in, and an hour later, off you go, long after they've cooled off.  On a reject, on the rare occasion the reject didn't require a return to gate for maintenance action of some kind, you have the Brake Temperature Monitoring System to tell you when the brakes are good to go even if you don't return to gate (most rejects are because of a Caution or Warning prior to V1 -  and if you reject in the "high energy" phase, usually above 80 or 90 kt, which is a callout during the roll, your airline will likely require you to return for a brake and tire inspection anyway, "liquid cooled" or not).  If the BTMS is MEL'ed, you will have to observe a minimum brake cool down time as per the associated MMEL Ops Procedure.

So yes there are times when regular brakes require you to sit and wait for a period of time, but it would happen on 1 departure in, well, thousands (departure delays from brake overheating, from pilots riding the brakes during taxi, is probably a bigger problem operationally).   In any case, in view of the actual operational impact, nobody would want to pay for such a cooling system even if it was feasible.


Where can I find the German GAFOR online?

You can find all the free aviation weather services of the DWD here:

https://www.dwd.de/DE/fachnutzer/luftfahrt/teaser/luftsportberichte/luftsportberichte_tabelle.html


What should I do to become a pilot for skydivers, in France?

Short answer: you need a commercial pilot's license. The drop zone will provide the extra training, it takes about a day (I worked at a skydive center for 10 years)

However, since you seem to not have any kind of pilot's license right now (or you would know this already) I will add that it isn't a full-time job at any except the busiest drop zones. Our pilots usually worked for a couple of years to build time and then went on to other aviation jobs. During those 1-2 years they had other income - flying for us was mainly a way to log flying hours without having to rent aircraft.


What is the procedure to turn an airplane when it flying?

Ailerons are but one type of primary flight control surface, which are used to roll the airplane about the longitudinal axis, thereby directing the lift vector generated by the wings from the vertical to the direction of a desired turn, thereby providing the required force to cause the airplane to change direction.  Ailerons aren’t the only primary flight control surfaces which can do this; other types can include flaperons, differential elevator inputs and differential spoilers.

Rudders are used to counter adverse yaw caused by the difference in induced drag created as a byproduct of aileron inputs, which cause the nose to swing toward the outside of the turn, resulting in uncoordinated sideslip and inefficient turning of the aircraft.  In the case of a V or Swallow tail, ruddervators fulfill the function of both rudders and elevators and would be used to counter adverse yaw as well.


How can I combine flight training hours flown under various legislations in a single logbook?

Based on what you've written, the main issue for you is TSA approval. As a foreigner, you can't receive initial flight training in the US from any school or instructor unless you have a TSA approval in advance. And you need one approval per school or instructor: if the TSA approved you for flight training at a 141 school, you can get training from that specific school only. To use another 141 school or a part 61 instructor, you would need a second, separate approval.

But, assuming that you do have (or can get) the TSA's approval then you can log the training time as usual. The instructor must endorse (sign) your logbook as described in 14 CFR 61.51(h):

  (h) Logging training time. (1) A person may log training time when
  that person receives training from an authorized instructor in an
  aircraft, flight simulator, or flight training device.

  (2) The training time must be logged in a logbook and must:

  (i) Be endorsed in a legible manner by the authorized instructor;

And your question about multiple logbooks has already been asked.


Have there been any studies on which fly-by-wire pilot interface is preferred; rate control or direct control?

I have no study to refer to, but I expect the results to differ very much from group to group.

For airline operations, I imagine the objective of the pilot is often to maintain a constant attitude, varied with a smooth transition to another attitude. This would be easy to achieve with the first option you describe.

For military operations, I think a rapid feedback is desired. This aligns better with the seconds option you describe.

When you would perform a study under pilots, the response you'll get will very likely be that they prefer whatever they are used to at the moment.


Is it possible to get into a spin situation while coordinated?

Yes, what you describe is perfectly possible. A stall in banked flight can result in a spin, given you fly the "right" plane.

My first flight in an ASW-20C was late in the afternoon, when most thermals had died down. I got a winch launch to maybe 350 m (the ASW-20 is rather poor in winch launches) and tried to find an updraft. In maybe 270 m I found one, but it was weak and narrow. So I slowed down to tighten the circle. Having flown a Discus all day before, I was not really alerted to watch out for a departure on stall. At some point the lateral stick force faded markedly, and out of the Discus habit I threw the stick into the circle so the inner aileron would deflect downwards to support the stalling wing. Bad choice! This aggravated the incipient stall, the aircraft rolled into the circle and pitched down. While the view from the cockpit before was blue above and green below, it got now all green. I was entering a spin.

The weakening stick force was the result of flow separation over the aileron, and while the Discus airfoil would still provide more lift with more deflection, the ASW-20 airfoil simply went into full stall.

I immediately pushed down and levelled the plane, and went on to land straight away, having lost maybe 100 m. It all took only seconds, and only long after the flight I could piece all details together. My next flight in the ASW-20 was when the thermals were much stronger. I went up to 1000 m and did stall training until I knew how it felt when stall starts and what my options are. I should had done this on the first flight, and do so on all subsequent new types I fly.


What runway alignment should I expect from a straight-in approach?

This is an interesting question because it turns out that RNAV approach criteria aren't defined in the TERPS as you would expect. Instead, there's a separate FAA order 8260.58 for RNAV approaches.

The TERPS does indeed give 30° as the maximum offset for most approaches (e.g. section 4-2-4) and 15° for VOR/DME RNAV approaches (section 13-3-4), but VOR/DME RNAV approaches are still based on ground stations (section 13-1):

  VOR/DME RNAV systems use signals based solely upon a VOR/DME, VORTAC,
  or TACAN reference facility. These systems use radials and distances
  from a reference facility to compute position and flight track
  information

On the other hand, the criteria for 'true' RNAV approaches not based on ground stations are defined in 8260.58 and they allow for offsets up to 30°  for approaches without vertical guidance (section 3-2-2):

  a. Offset. When the final course must be offset, it may be offset up
  to 30 degrees (published separately from vertically guided) when the
  following conditions are met:

  (1) Offset ≤ 5 degrees. Align the course through LTP.

  (2) Offset > 5 degrees and 10 ≤ degrees. The course must
  cross the runway centerline extended at least 1500 feet prior to LTP
  (5200 feet maximum).

  (3) Offset > 10 degrees and ≤ 20 degrees. The
  course must cross the runway centerline extended at least 3000 feet
  prior to LTP (5200 feet maximum). For offsets > 15 degrees, CAT C/D
  minimum published visibility 1 SM, minimum HAT of 300 feet.

  (4) Offset 20 to 30 degrees (CAT A/B only). The course must cross the runway centerline extended at least 4500 feet prior to the LTP (5200 feet
  maximum).

Since the approach you showed doesn't have vertical guidance, it would fall under this section and therefore the offset of 16.76° marked on the plate is normal.


What are the various thrust modes in the Airbus A320?

A normal climb is performed with a constant thrust1 and a constant speed. The autothrust system will take care of the constant thrust (THR CLB) and the autopilot (or flight director for manual flight) will take care of the constant speed. This means you maintain the target speed by pitching up or down. If the speed is below target, pitch down to increase speed, and vice versa.
The same is true during a descent. The autothrust will maintain idle thrust (THR IDLE) and the autopilot or flight director will maintain the target speed by pitching down.
During cruise, where the altitude remains constant, the target speed needs to be achieved by setting the correct amount of thrust. Now the autothrust system is responsible for maintaining speed and will show SPEED or MACH on the FMA (Flight Mode Annunciator).

The A/THR modes are selected automatically in conjunction with the AP/FD modes (except ALPHA FLOOR).

(Airbus A320 FCOM - Autoflight - Flight Guidance - A/THR Modes)

1The actual thrust produced by the engine is not constant, it depends on altitude. The FADEC will compute a thrust rating limit depending on the selected thrust lever position:

The FADEC computes the thrust rating limit for each thrust lever position [...]. If the thrust lever is set in a detent, the FADEC selects the rating limit corresponding to this detent.

(Airbus A320 FCOM - Powerplant - Thrust Control System - Thrust Rating Limit)


What is the difference between "R/C", "Drone", "UAV"?

Drones are simply the common name for Unmanned Aerial Vehicles. Representatives from the industry and the military use the term UAV for the aircraft and UAS (Unmanned Aerial System) for the whole system- including communication system, on ground controller etc.

In general, technical publications call them UAVs or usually UAS's and rarely (if ever) drones. On the other hand, the mainstream media refers to them usually as drones as it is easy to communicate.

The ICAO (International Civil Aviation Organization) calls them remotely piloted aircraft. However, there is a subtle difference in using this word as it means that it is being flown by a pilot (controller) on ground.

Though this may be technically true, most of the UAVs, at least those used in the military are capable of highly automated mission profiles (in fact, they depend on the controller only for weapons release) and are on the way to full autonomy.

The choice of wording is one of semantics i.e. about the meaning which is to be conveyed. For example, the nobody wants a system that goes and kills someone without human intervention. So, the USAF calls the MQ-9 Reaper a Remotely Piloted Vehicle in its official page and a UAV in press releases, but not a drone, as it has negative connotations in public mind.


Aborted take off due to not closed cargo doors. How this will be signalled?

You will typically get a DOOR OPEN alert displayed on the EICAS system.  A competent crew would have spotted such a discrepancy before pushback.


How does MCAS communicate with other systems to know if the flaps are retracted or not?

MCAS is implemented on the Flight Control Computers (FCCs). The FCCs communicate over an aviation data bus, ARINC format. The B737NG used ARINC 700 series standard for communication - sensor information is linked to the FCCs via the avionics data bus. The B737MAX may or may not use a later standard ARINC bus.

There are two FCCs on the B737MAX. From this link:

  Computer redundancy. As of 2019, the two flight control computers of Boeing 737 never cross-checked each other's operations; i.e., each was a single non-redundant channel. This lack of robustness existed since the early implementation and persisted for decades. The updated flight control system will use both flight control computers and compare their outputs. This switch to a fail-safe two-channel redundant system, with each computer using an independent set of sensors, is a radical change from the architecture used on 737s since the introduction on the older model 737-300 in the 1980s. Up to the MAX in its prior to groundings version, the system alternates between computers after each flight.[191] The two computers architecture allowed switching in flight if the operating computer failed, thus increasing availability. In the revised architecture, Boeing required the two computers to monitor each other so that each one can vet the other.

So not only do the FCCs know if the flaps are retracted, they now know if their computations correlate.


Can a holding pattern be in class G airspace?

By definition, Class G is uncontrolled airspace so the only separation you will receive there comes from using your Mk I eyeballs and good judgment.  A controller is not going to dispatch you to hold in uncontrolled airspace.


How to calculate W/V from true HDG/TRK/GS using a CRP-5 flight computer?

To work this problem in reverse:

Set the True Course (Track) at the Index and slide the grommet over the Ground Speed (GS) of 242 knots:

Draw a dot with an arrow behind it, marking the wind vector at the intersection of:

a)  8° right of center because the wind correction angle or heading is right of course (74° TH minus 66° TC); and

b)  230 True Airspeed (TAS)

Now, above, you are able to visualize the flight.  You could even draw your airplane in the middle and see the wind is a right quartering tailwind.

Finally, rotate the wind to the Index to read the answer.  Slide the center grommet over any line that's easy to read.  Read the wind speed up from the grommet (35 knots) and wind direction (from 180°) at the index:


Why isn't there some optional setting that can precisely move thrust levers jointly?

When the levers are set manually to the same position, the engines depending on their aging will not develop the same nominal thrust, some differences will appear on the indicated EPRs or on the indicated N1s, so no point to have them linked together.

With modern aircrafts, for instance the B777, even when flying manual thrust, in flight, when the levers are  set just close to each other, an automatic « trimming » function is automatically activated, it is transparent to the pilots and it corrects the engines thrusts as similar as possible by sending corrective orders directly to the FADECs, but however also preventing the beat noise that might occurs with fans having exactly the same speed; this occurs without any motion to the levers.

Taxiing with a single engine out of two is frequent for fuel consumption consideration and for noise abatement in many airports.

While forced to wait in a long chain for your turn to take off, and advancing step by step, pilots do use frequently one engine out of two.

On modern aircraft, you do not fly manual thrust but with autothrust or with autothrottles

On AIRBUS, the throttles positions have notches, so that when you select takeoff, the notch will set the throttles at similar position, nevertheless the commanded thrust do not correspond to the EXACT throttles positions but to a computed FADEC order.

On AIRBUS, at thrust reduction altitude the throttles are set to position CLIMB, for all the remaining flight, the levers remain there, and the thrust is managed by the autothrust


What are the differences between a GPS coupled autopilot and a GPSS autopilot?

Pugz provided some very good information back on September 29th.  As I recently installed a Garmin GTN 650 and add S-TEC GPSS to my 35 year old S-TEC 60-2 autopilot I thought I might respond also.  As I did this installation myself I am quite familiar with the wiring involved which helps in understanding how the autopilot responds so differently to GPSS (GPS Roll Steering) than it does to the CDI (Course Deviation Indicator).  First we need to understand that after installing GPSS the autopilot has two completely different interfaces.  When in NAV mode the autopilot responds to the CDI for lateral guidance (and the CDI glide slope if the autopilot has that capability like my 60-2 does.)  When in HDG mode the autopilot would normally respond to the Heading Bug on the Directional Gyro but if GPSS is installed the autopilot actually has two separate functions while in HDG mode:  1) Follow the HDG bug on the DG; 2) Follow the GPS Roll Steering commands that are provided by the GPS via ARINC 429 output that is routed to the autopilot GPSS module and converted into Heading Commands as if the HDG bug were providing them.  In order to implement this the GPSS module has a switch to change from HDG mode to GPSS mode.  As far as the autopilot is concerned he is just getting heading commands from a HDG bug on the directional gyro.  The autopilot has no idea that he is being driven buy the GPS while in GPSS mode.  Just imagine that a very skilled pilot is operating the HGD bug on the DG and the pilot knows exactly when and how much heading change to make in order to turn smoothly on the next route segment or intercept that route segment if off course. This is exactly what is happening except that the very skilled pilot happens to be the GPS receiver.  The GPS knows exactly what heading changes need to be made and when to make them in order to guide the aircraft around a procedure turn and intercept the final approach course.

The new Garmin GI-106B CDI that I installed along with the GTN 650 still has some very important functions.  After the GPS has guided the autopilot (via GPSS) through the entire route and possibly a procedure turn course reversal and intercepted the final approach course I switch the autopilot from HDG mode to NAV mode in order to engage the autopilot on the CDI.  Now if I am flying an ILS or RNAV LPV approach the autopilot has both vertical and lateral guidance via the CDI.  The CDI will either be getting input from the ILS signal or from the GPS depending on what has has been selected on the GTN 650.  Both autopilot interfaces are still important (HDG/GPSS & CDI) but the autopilot CDI interface is used only for the final approach where vertical guidance is needed.  Most of flight is best flown with the autopilot engaged in HDG mode either flying on the actual heading bug (being vectored) or with GPSS engaged and the GPS is turning the virtual heading bug for you in order to fly the programmed route.


Where can I find drawings or diagrams of the Boeing 737-800's internal layout?

Check out the "Airplane characteristics for airport planning" document for the 737, espcially from page 47: http://www.boeing.com/assets/pdf/commercial/airports/acaps/737.pdf

These kind of documents are created by the airplane manufacturer and are often publically available.


What use was there for Boeing to include customer numbers in their aircraft model names, and why did they end this practice?

It's an easy way to know what configuration options "this" aircraft has, long after it has left the factory.
Let's say that airline 1 ordered a bunch of 737's with one cockpit jumpseat & two aircraft batteries and the 3-hour cargo fire suppression option -- stuff you might expect for overwater flights.  They got, hypothetically, the 737-7E1 (just making that up.... a 737-700 with customer code E1).  Then airline 2 ordered a bunch of 737-700's with two cockpit jumpseats & a single aircraft battery and the 1-hour fire suppression system... a more short-haul sort of fleet.  And let's say that their code was the 737-7E2.  Years later, all of those aircraft from both airline 1 and airline 2, and perhaps others, have been sold to airline 3.  Airline 3 has some 737-7E1's and some 737-7E2's.  And if you're conversant with the codes in that fleet (as mechanics & others at Airline 3 would be), then you can see on a list that "this" aircraft is a -7E2 and so you know that it's the configuration with both jumpseats, one battery, and etc.
Those customer codes don't deal with things like the passenger cabin seating configuration; those can be swapped out pretty easily.  But stuff like batteries & cargo fire bottles and plumbing for an extra O2 mask in the cockpit doesn't tend to change, so those sorts of things get captured in the customer codes.
As to why they abandoned them, my only guess is that they may have decided to standardize all their product by removing customizations -- a 787 is a 787 is a 787, and (perhaps) they don't let customers configure them in ways that, down the road, may make the aircraft less desirable for somebody looking to buy or lease a fleet that doesn't have lots of variants between jets.
There are stories from guys who flew freighters where ever aircraft on the ramp was different in some way -- even though they were all the same type.  Newer INS, older INS, different flight directors, sometimes even different types of engines, etc etc.  For a freight operation looking for any aircraft they can get cheap, that lack of standardization may be no big deal. But for other operators, not having to deal with the headaches of dissimilar aircraft in the fleet may be an incentive to choose "this" type over "that" one.


How do pilots and controllers deal with TFR's that lie directly on an approach?

The NOTAM itself answers your question:

  THE RESTRICTIONS DESCRIBED ABOVE DO NOT APPLY TO THOSE AIRCRAFT
  AUTHORIZED BY AND IN CONTACT WITH ATC FOR OPERATIONAL OR SAFETY OF
  FLIGHT PURPOSES, DEPARTMENT OF DEFENSE, LAW ENFORCEMENT, AND AIR
  AMBULANCE FLIGHT OPERATIONS.

As long as the pilot is in contact with Air Traffic Control and has been cleared through the TFR, they can safely fly though the airspace.


Are there any locations where I could launch a rockoon with minimal red tape?

NAR / Tripoli
I would recommend getting in touch with NAR or Tripoli about your needs. They handle these sorts of things all the time. TBH if you or your range officer hasn't been certified by one of these bodies you shouldn't be launching anything larger than an E sized engine.

Both organizations offer memberships including training, certification, participation in sanctioned events, and liability insurance (some of which may carry an additional fee.) The minimal red tape stipulation will be achieved if you can join an existing sport launch which meets your needs. The biggest issue will likely be whether or not that particular launch is cleared up to your intended altitude.

NAR and Tripoli have had agreements in place with the FAA since the October Sky days and coordinate launches with the feds to make sure everything is safe and above board. If you can't join an extant sport launch, you can set up your test as a sport launch of its own. The fee you pay will be tiny in comparison to FAA fines and probably also cheaper than relocating to wherever there aren't rules.

FAA Waiver
You can, of course, choose to set everything up for yourself and apply for an FAA waiver on your own. It takes about as much patience as a moderately complicated DMV procedure. Generally speaking you can be approved for any class G or E airspace and for Class A airspace that is not in or near an air route.


Can the big "X" sign be used for purposes other than runway closure?

There are a couple of different NOTAM's stating runway closures at KLAX, including the below. Bear in mind that runways are closed regularly for maintainence (resurfacing) just like roads. No drama about that.

LAX 05/189 LAX RWY 07R/25L CLSD DLY 0800-1300 1705300800-1706011300
LAX 05/157 LAX RWY 07L/25R W 1300FT CLSD. DECLARED DIST: RWY 07L TORA 9665FT TODA 9665FT ASDA 9255FT LDA 0FT. RWY 25R TORA 10808FT TODA...
LAX 05/156 LAX RWY 07L CLSD TO LDG 1705252200-1708190659

There are also several closed taxiways.


Why don't some airlines assign seats to passengers?

It is mainly used by low-cost single-class cabin airline companies to make the reservation process simpler.


How much computing power is needed to keep commercial and military planes flying?

For commercial airliners: the computing power is set during development and certification of the type. The A320 was developed in the 1980s and still uses Intel 80186 and Motorola 68020 processors. Your i7 CPU would be able to run rings around anything on board of the average airliner.

But processing capacity is of secondary importance to airliners, safety and redundancy are in the limelight. Any processor capacity that can do the job is good enough, and is only the start of all the aspects that go into certifying an airliner including its systems.

Image source

Military planes are different, in that the requirements are more pressing and the accepted risks are higher. Yes modern fly-by-wire planes use digital systems, however when the F-16 first came out with a fly-by-wire control system, it was a quadruple redundant analog system, with a digital processing requirement of zero. These were upgraded to digital fly-by-wire in the block 40/42 upgrade in the early 90s, so again the fly-by-wire used pretty primitive processors by today's standards.

Generalising, the long development and certification/ready-for-mission time of aircraft systems means that any system on board uses processing power that is behind the latest-to-market specs.


How much power do planes use when taking off at London City?

Let's say there is an infinite runway, and a twin-jet capable of flying the whole route on one engine.
The jet starts its takeoff roll at maximum thrust, and at 40 knots an engine quits. Does the crew continue or not?

If they continue, they'll veer off the runway. Because the asymmetric thrust is huge and the airspeed is low, they won't be able to keep the plane on the centerline with the rudder.
Enter Vmcg

Vmcg is defined as the minimum speed, whilst on the ground, that directional control can be maintained, using only aerodynamic controls, with one engine inoperative (critical engine on two engine airplanes) and takeoff power applied on the other engine(s).

Why is it important?
The lower the thrust on short runways, the more you can carry...
It may be counter-intuitive, but here's why: there are three types of thrust reduction on takeoff:

Derate
Assumed temperature (aka flex)
Derate + flex

(Availability of the modes depends on the options available for the type and the options chosen by the airline for their fleet.)
Derate vs. flex and effect of derate on takeoff weight

The minimum control speeds associated with the FLEX take-off are related to VMCG/VMCA at TOGA thrust. Therefore, should the aircraft suffer an engine failure at V1, there is no limitation on selecting TOGA thrust on the remaining engine(s).
DERATED THRUST TAKE-OFF
A reduction in take-off thrust leads to lower VMCG/VMCA and hence, a lower V1. When taking off from short or contaminated runways where ASDA [Accelerate-Stop Distance Available] is the limiting factor, a reduction in the minimum control speeds may generate a take-off performance benefit and a higher MTOW.
As opposed to a FLEX take-off, the selection of TOGA following an engine failure during a derated thrust take-off is prohibited as long as speed remains below the first flap/slat retraction speed for the take-off configuration. The selection of TOGA below this speed in these configurations may result in loss of control due to VMCA considerations.
— A330/A340 Flight Crew Training Manual

Taking off from LCY
A BA A318 taking off from LCY headed to New York with lots of fuel might as well be using reduced (derate) thrust because of this shorter runway.
In short, it's very hard to compare even if the only variable is the runway length.
Flex example
The CFM56-5B3 jet engine (powers the A321) can reduce thrust by 35% when a Δ35°C assumed temperature is used. So 120 kN of thrust becomes 78 kN (per engine).

Further reading:

Airbus: Flex/Derate, Engine Bump and Derated climb
CFM: A320 Flight Ops Presentation


Why does the Boeing 747 have a nickname but other aircraft do not?

How Boeing 747 is called Jumbo Jet?

The Boeing 747 is the world's first wide-body aircraft. For a long time, it was the world's largest passenger aircraft1. When Boeing was designing the 747 in mid-1960s, it expected that in the near future supersonic travel would become the norm. Hence, there would not be a need for the passenger version of 747. Because of this, 747s were designed in a way that they can be easily converted into freighters.

Pan Am, being one of the first customers of 747, wanted to fit two rows of cargo containers2, instead of one. This meant that the fuselage had to be at least 16 feet wide, wider than any airliner at that time. This would have worked fine for cargo, but it would make loading and unloading passengers very time-consuming. To accommodate this, Boeing engineers designed two aisles, which ran parallel through the length of the aircraft, hence the term wide-body was coined.

When the press noticed the huge size, they described it with the catchy term Jumbo Jet. It is also known as Queen of the Skies but that is not common.

  Do other airplanes have nicknames?

Airbus A380 dubbed as superjumbo by media. The only A380 sold as a business jet is called Flying Palace.

Although there aren't official nicknames of airplanes, almost all airplanes earned some nick names. This list contains nicknames for mostly military aircraft.

1 Airbus 380 took over as world's largest passenger airplane in 2007.
2 At that time, cargo containers were cubes that measured 8 feet (2.44 m) per side.


What is the late BF109's (G models) internal fuel capacity?

The BF109G could carry 400 liters of fuel internally, and up to two 300 liter drop tanks externally.

You can also find the information in the flight manual, but you have to be able to read German. It's on page 7, under "Kraftstoffanlage".


Does it violate any regulations for a bag to sit on the flight deck floor?

There are some relevant links in the Cabin Saftey Index document under "crew baggage" indicating that all bags must be restrained. The document points to

  §121.576   Retention of items of mass in passenger and crew
  compartments.

  The certificate holder must provide and use means to
  prevent each item of galley equipment and each serving cart, when not
  in use, and each item of crew baggage, which is carried in a passenger
  or crew compartment from becoming a hazard by shifting under the
  appropriate load factors corresponding to the emergency landing
  conditions under which the airplane was type certificated.

The question remains if the cockpit is in anyway different than a "crew compartment" but I would say that could be applied to your question.

However if the bag in question is a flight kit then different rules apply which can be found here:

  A. Flightcrew Flight-Kits. Particular attention should be given to
  compliance with part 121 regarding restraints for any baggage carried
  on the flight deck. Flightcrew flight-kits are not items of crew
  baggage. This policy also applies to aviation safety inspectors (ASI)
  and additional flightcrew members. While it is logical that
  flight-kits be placed so that movement is restricted, the FAA does not
  intend that they be restrained in a manner that would interfere with
  the needs and functions of the flightcrew.

I can not find a further definition of "flight-kit" and/or if you can or cant put your lunch in it.


How does the DA 40 NG automatically control the mixture, pitch and power by just providing one throttle?

According to Diamonds website the NG engine is a:

  Austro Engine AE 300 turbocharged common-rail injected 2.0 liter diesel engine with 168 hp and EECU single lever control system

The prop is a:

  3 blade MT hydraulic constant speed propeller features advanced blade geometry for efficient performance, low vibration and noise. It is automatically controlled by the engine’s digital engine control through a conventional hydraulic governor.

From the sounds of it, it is as close to a full FADEC (Full Authority Digital Engine Control) unit as you can get

It is controlled by a computer module just like your modern fuel injected car.


Does European airspace use the metric system?

European Civil Aviation Authorities use the imperial system to depict altitudes and airspace restrictions (feet), speeds (knots) and distances (nautical miles).

Some VFR aircraft have speed indicators in km/h, gliders can have altitude and variometer in meters and meters/second and apart from a special ICAO VFR chart being available in metric in Germany, the AIP itself and all other charts always use imperial units.

Related question: What is the measurement system used in the aviation industry?


What's Permaswage / Harrison tube repair?

A quick google for "Permaswage/Harrison" reveals that

  Permaswage is the technology leader in the fluid fitting industry providing proprietary and standard components, tooling, and training to all major aerospace companies globally.

"Harrison" seems to refer to a variety of internal swage fittings that are separable ridge tube end fittings commonly used in aerospace fluid transfer applications:

  They are also referred as “Harrison”, “Stanley Aviation” or “Sierracin” fittings, due to the history of the product.

From this, I would deduce that one can use these products to effect a repair to hydraulic lines with these methods/products because:

  Internal swaging is a mechanical method for the attachment of fittings to tubing. This is accomplished by forming tubing outward into grooves within the fitting.

--From the "Harrison" link


AMDAR (Aircraft Meteorological DAta Relay) is a program established by the World Meteorological Organisation to gather weather data from around the world. It's run through a number of local and regional AMDAR organisations who negotiate with partner airlines arrangements to use existing aircraft sensors to gather and report weather data on each flight.

The gathered data is relayed by satellite or radio to ground stations and then forwarded on for processing and distribution.

(I've paraphrased from this source)

So, there is no specific AMDAR equipment. The AMDAR system is implemented by arrangement with partner airlines, and may be installed on some or all of the airline's aircraft that already carry suitable sensors.

There is no mention of a requirement that an airline partner with a regional AMDAR organisation, and thus no requirement for their aircraft to carry the system.

It's not clear from the pages at the WMO what the nature of the collaboration between the local AMDAR organisation and the airline is, so there may be some payment to the airline, or there may be some benefit in kind: free or reduced cost access to meteorological reports, perhaps.


Can TCAS be used to confirm "traffic in sight"?

No, "in sight" or "visual contact" means seeing the actual traffic visually, with your eyes. When you report "traffic in sight," then the controllers are allowed to issue a clearance such as "maintain visual separation" or "follow that traffic, cleared visual approach...". They can't issue those clearances when you only see the traffic on TCAS. In fact, having the traffic on your TCAS display doesn't really help them.

The only time that I'll even mention that I have the called traffic on TCAS is in a situation where it may save the controller extra transmissions pointing out the traffic "now at 2 oclock moving to 1 oclock" etc. If he knows that I'm getting bearing from TCAS & will call it when I see it, that may save some radio congestion, but until I see the traffic and report it in sight, he can't clear me for anything based on visual contact.

TCAS is a great tool for collision avoidance & for awareness, but it isn't designed as a "follow that traffic" tool.


How does one deal with a UNICOM operator directing aircraft like at a towered airport?

You're almost certainly talking about a UNICOM operator, who is just an airport (FBO) employee who gives information to pilots on their request. The FAA's Pilot Handbook says:

  UNICOM is a nongovernment air/ground radio communication station which
  may provide airport information at public use airports where there is
  no tower or FSS. On pilot request, UNICOM stations may provide pilots
  with weather information, wind direction, the recommended runway, or
  other necessary information. If the UNICOM frequency is designated as
  the CTAF, it will be identified in appropriate aeronautical
  publications.

The important point is that UNICOM is not ATC. A UNICOM operator cannot give you instructions, clearances or require you to do anything. He can only give you information, and as PIC it's up to you to decide how to use that information.

The article that Porcupine911 mentioned is a great example of that. A student pilot thought that UNICOM was telling him which runway to land on, whereas in fact the operator was only recommending a runway (presumably based on the prevailing wind or whatever). Unfortunately, the operator recommended the opposite runway to the one that was actually in use by other pilots.

Like pilots, UNICOM operators vary in their experience and competence. A good UNICOM operator (in my opinion) will give you the local wind and altimeter information, tell you if there are other aircraft in the pattern or nearby, tell you which runway is in use by those aircraft, and give you any essential safety information (like a closed runway). But as PIC, I'm still going to listen to CTAF and AWOS and look for other traffic before choosing a runway and joining the pattern. It's also common for no one to reply to a UNICOM call (because the operator is out fueling aircraft in his other role as lineman, for example), in which case you're going to have to sort things out without it anyway.

So there's no need to "report" anything: UNICOM operators are a well-known and official service, but you have to know how to use them and what their limitations are.


Could hydrazine be used as a scramjet propellant?

Technically yes, you could use hydrazine in a scramjet.

But there's no reason to do so. The singular purpose of building a scramjet is to get air into the combustion chamber, so that you don't have to use a monopropellant, which all have high cost and poor energy density.

Kerosene or H2 won't burn without air, so you need a scramjet or an oxygen tank to burn them. Hydrazine doesn't, so you can burn it in a rocket, at higher pressure with more efficiency and better aerodynamics.

Advantage: Rocket engines have a thrust:weight ratio of up to 133:1, scramjets about 2:1. So an equivalent rocket is up to 66 times lighter than a scramjet.

GE's patent refers to the use of a small amount of hydrazine in a catalyst-like role, or more accurately to act as a fuel/air mixer.


Would jet fuel for an F-16 or F-35 be producible during WW2?

Jet fuel is mostly kerosene, with some aromatic hydrocarbons mixed in for stability, temperature range and the like. You could probably run military jets on pure kerosene if they were magically transported back to WWII, but you wouldn't have to as it would have been possible to make reasonable jet fuel. The Jet-A standard was made in the 50s, and there were no major differences in the fractions available from WWII.

Before it was an engine fuel kerosene was primarily used for heating and lighting, and it was widely used across the world for that purpose in WWII. It still is in some places around the world where electricity isn't available. The aromatics in jet fuel aren't anything special, so it would have been entirely possible to make a jet fuel.

You could go farther back than WWII and still run a jet on raw kerosene as the modern process to distill it from petroleum was invented in the 1850s.


What could cause lower torque than normal during cruise in a King Air 300?

My guess, and it's just a wild guess, is humidity based ice forming somewhere in the inlet and/or the inlet plenum, more or less similar to carburetor icing.  The symmetrical torque drop is from the flow restriction and the random vibration is when the ice breaks up. I'll guess that you were flying though what appeared to be clear or clearish air with the inlet/plenum anti-ice turned off.

Double simultaneous random mechanical malfunctions are just too microscopic from a probability perspective to be likely at all.  A phenomenon like that, that happens to both engines at the same time,  must be due to an external source related to the atmosphere the aircraft is flying through, unless there is some other system on board that impacts both engines equally if it malfunctions, and that's something you won't generally see design wise.

I would try this question on PPrune Forums.  Somewhere there is a King Air or Twin Otter driver that's had the same experience.


Are there any best practices for transitioning from paper logbooks to electronic logbooks?

Logbooks are an interesting blend of personal and professional recordkeeping.  The FAA doesn't really make a big deal about what method you use to log your flight time, just as long as you log all flight time which you're going to later use to justify currency or a new certificate.

This means that you can do whatever works best for you, as long as you (and your future employers) are happy with it.

When I transitioned to Safelog, I decided to spend a few weeks worth of evenings and just enter everything, line by line.  I did this because I had a lot of spare time, and because from now on I've got a pristine digital copy of everything, which is a nice feeling.

However, this is certainly not necessary, and there is no reason why you couldn't summarize your totals with one or a few line items.  In fact, Safelog provides a function to do exactly that: you create a pseudo-aircraft type which is defined as "summarizes several aircraft".

You can get as coarse (1,302 hours in airplanes) or as fine (389 hours in blue C-172M's with the funny starter that sounds like you just dropped a shot glass in a garbage disposal) as you want.

I would say that whatever you choose to do, just be sure that you enter it using a format which will be compatible when you switch from Android to iPad.  It's bad enough to do it once, why put yourself through the hassle of doing it twice?


Is there a reason for a jet liner to raise the nose wheel early during the take-off run?

It's a 727 take-off technique used on unpaved surfaces.

Glimpse of the real deal here.

Possibly an old-timer was showing someone how it was done. Or someone was doing a recurrent for it.

It's to avoid nose gear damage if it hit a rock, or damage to other parts if said rock/debris were to be deflected. Also to avoid digging the nose gear into the soft field—reducing the rolling friction.


What are the weather requirements to log an instrument approach?

Update with relevant info from InFO 15012 (I'm skipping the FTD portions as not relevant to the question, and including the simulated parts but italicizing them as they're useful but also not relevant). Translated, you can log an approach when:

it is flown solely by reference to instruments, and

it is flown in IMC, and Actual Instrument time is logged, or
the PF is using a view-limiting device, and Simulated Instrument time is logged;

you must fly the complete approach from a feeder or the IAP (or Vectors to Final) and remain established the whole time. This means you fly initial, intermediate, and final segments, unless you're on vectors.

if flying the approach in IMC, you may log an approach that:

continues to DA/DH or MDA in actual, or
becomes VMC before DA/DH or MDA, provided you are inside the FAF.

if simulating the approach, you must continue to the DA/DH or MDA under the hood (or other VLD);

That's pretty much it. Here's the source text:

  A pilot may log an IAP for currency or training when the pilot
  accomplishes the IAP in accordance with the following conditions:

  When conducted in an aircraft, flight simulator, flight training device, or aviation training device, the pilot must operate that
  aircraft or authorized training device solely by reference to
  instruments [§ 61.51(g)(1)];
  When conducted in an aircraft, flight simulator, flight training device, or aviation training device, the pilot must be established on
  each required segment of the IAP to the minimum descent altitude (MDA)
  or decision altitude/decision height (DA/DH);
  When conducted in an aircraft simulating instrument flight conditions, a flight simulator, a flight training device, or an
  aviation training device, the simulated instrument meteorological
  conditions (IMC) must continue to MDA or DA/DH; and
  When conducted in an aircraft, the flight must be conducted under actual or simulated instrument flight conditions [§ 61.51(g)(1)].
  When conducted in an aircraft maneuvering in IMC, and the aircraft transitions from IMC to visual flight conditions on the final approach
  segment of the IAP prior to or upon reaching MDA or DA/DH.

Previously, I linked to Rod Machado, who cites the FAA in an answer to this that I quite like, and which was pretty frequently referred to when I was instructing at a flight school:

  Once you have been cleared for and have initiated an instrument approach in IMC, you may log that approach for instrument currency, regardless of the altitude at which you break out of the clouds.

...but this is not the latest knowledge anymore. It's functionally pretty close to the InFo rules for IMC approaches, though!


If Space Shuttle flies "like a brick", why does it need the wings?

The small wings make it fly like a brick. Without the wings it would fly like a stone.

Seriously, you are taking the expression too literally. The Space Shuttle is landing like a glider plane with a (not so good) glide ratio of about 4.5:1 (see What was the Space Shuttle's glide ratio?). No brick would be able to achieve that.

Designing the Space Shuttle as a lifting body ( ≠ brick) was actually considered. It appears that a lifting body design was not able to comply with the flight envelope requirements.