Why does it take so much fuel to start a jet engine?

The first figure, 1 litre per mile, is very wrong. The second, 39 to start, is most probably the fuel required for a warm up from a cold start. The Abrams tank weighs 62 tonnes, so you won't get 1 mile on a litre. Its fuel consumption is quoted as 0.6 mpg, or 1.66 gallons per mile, which is 6.3 litres per mile. Quite a difference.

The engine is the Honeywell (previously Lycoming) AGT 1500. It has a two spool gas generator, with a two stage power turbine. It features a heat exchanger through which the HPC exit air flows, to preheat it from the exhaust gas, prior to combustion, to improve engine efficiency.

The engine has a tactical idle that keeps it running at 1500 rpm instead of 950 so that it can rapidly accelerate from a stationary position if needed to avoid or engage a hostile force. In tactical idle it consumes 30+ gallons per hour, instead of 10 at the non tactical idle setting.

It's stated that "in 1990, Project on Government Oversight in a report criticized the M1's high costs and low fuel efficiency in comparison with other tanks of similar power and effectiveness such as the Leopard 2. The report was based on data from U.S. Army sources and the Congressional record."

Some critics say the tank fuel consumption is so poor, that in combat, it has to often wait for the fuel supply logistics to catch up. Other reports deny this. (See paragraph at the very top of the page).

The M1 Abrams was chosen after a competition in June 1973, between the Chrysler Corporation and the Detroit Diesel Allison Division of the General Motors Corporation to build prototypes of a new tank designated M1, and later named the Abrams tank. In November 1976, it was announced Chrysler won the competition.

  The M1 was faster and more maneuverable than its predecessors in the M60 series, while offering a lower, smaller silhouette. Besides the substantial gains in performance, the Textron Lycoming AGT-1500 turbine engine was far more reliable than the diesel tank engines then in use with the Army. There was still another benefit. The engine change, despite a penalty in fuel consumption, also resulted in much quieter operation, so much so that soldiers encountering the tank in early maneuvers started calling it "Whispering Death".

The Abrams wikipedia page also states a figure of 6.3 liters per mile, and also states the value of 38 liters to start. As suggested by user3528438 (thank you), the 39 litres (10 US gallons) is quite probably the fuel required to complete a warm up from a cold start. At the tactical idle setting, this would be the fuel consumed in about 15 to 20 minutes.


Why are pilots deemed unfit to fly after emergency ejection?

Ejection Seats are not a free ticket out. They are incredibly violent and rough on your body. This newspaper article has a more chilling quote from an interview:

  About one in three will get a spinal facture, due to the force when the seat is ejected - the gravitational force is 14 to 16 times normal gravity and it might be applied at 200G per second. Bruising and abrasions are typical from the shock of the chute opening or the air blast. In the early days, there were cases where pilots would eject into very-high-speed air and it would whip their arms behind and break them, pop their shoulders out; same thing could happen to the legs. Source

Hence, it is very possible to get back pains and a host of other problems as a result of ejecting. Since these type of things are not that easily reversible, you'd rather take the safe path and remove then from the cockpit than put then back in a work environment that known is pretty hard on your body. Aircrew seem to agree:

  “It was the most violent thing I’ve ever felt in my life,” says one of the B-1 crew members, whom the Air Force asked me to identify as “Captain IROC.” “I lost a full inch in height,” because his spine absorbed such tremendous G-forces. Source

Modern ejection seats are however increasingly intelligent and will gauge the ejection force applied to the conditions, cutting down the number of serious cases.

This paper discusses the symptoms of four individuals who crashed their jets in mid-air. The medical problems encountered with ejection can be classified as follows:

  Injuries from the emergency that causes ejection—fire or collision.
  Canopy jettison: burns from “MDC splatter” and cuts from fragmented plastic. For these reasons, aircrew are always advised to wear their visors down, to protect the face.
  Firing of ejection gun: spinal injuries.
  Entering airflow: wind blast may cause lung damage; seat tumbles at variable speed, which may be as high as 180 rpm. (All seats have a drogue parachute or deployable aerodynamic panels to prevent tumbling); flail injuries to extremities.
  Parachute deployment: snatch injuries.
  Landing: lower limb injuries.


Do you need FAA approval to land a helicopter on Miami Beach?

No; you may need permission from the local authority.  FAA doesn't regulate where you can land or take off.


Does maximum altitude increase when pilot is acclimatised?

Yes, maximum possible altitude at which a pilot can fly an Unpressurized Airplane without the need for supplementary oxygen does increase with acclimatisation. But the international aviation laws do not take this into account and hence they have a general altitude limit for unpressurized flying without supplementary oxygen.


What are these "pimples" on the jet engine for?

They are the roots of the variable stator vanes that control the direction of the airstream as it enters each compressor stage to manage and optimize the angle of attack of the compressor blades in each stage.  The vanes are connected to the ring shaped gang bar and somewhere around the circumference there is an hydraulic actuator, or a series of them, that drives the gang bar rings to move all the vanes connected to it at the same time.  The hydraulic actuator is usually powered with pressurized fuel and is operated by the fuel control system to keep the vanes at the optimal rotational position.

This video (thanks, @Mackk) shows how the vanes operate:


Are low pressure (LP) compressors and booster compressors the same thing?

The same. LP (low pressure) compressors in turbines are sometimes referred to as booster compressors.


The overhead bins are usually mounted to the aircraft structure. For example, in case of Boeing 737, they are mounted to the stingers using tie rods. From an accident report of Boeing 737-400:

  The forward inertial load is reacted by a diagonal tie, mounted at one end to stringer 6 or 7 in the fuselage crown and at the other end to a fitting on the upper surface of the bin. The vertical and lateral loads are reacted by short tie rods attached to the fuselage.

B737-400 overhead bin attachment. Image from the same report.


Change of Roll moment with change of wing position (z-direction)

For a first approximation, the coefficients will be similar enough, but not exactly identical. As you correctly point out the moment arms will be the same, but the interference effects of the wing-fuselage joint may not.

That is to say, your assumption that the lift distribution will remain unchanged will likely not hold out in reality.

The stability derivatives will not be similar, however.


When I'm flying east, pointing east, with a compass heading of about 090 (i.e. 90 degrees), when I land straight ahead I will be landing on runway 9. Just after I pass over the runway threshold, at about 50 feet above the runway, I'll overfly the big "9" painted on the runway, and I'll touch down some hundreds of feet beyond it. If I then roll all the way to the far end, the eastern end, of the runway, I'll reach the "27" painted there.
Conversely, if I'm east of the runway & flying west, my compass heading will be about 270 and I'd land straight-in on runway 27. My compass heading as I'm landing (or taking off) corresponds to the designation of the runway that I'm using.


In areas where the ATC provides the altitude in meter (China (PRC), North Korea, and Russia), depending on the equipment (altimeter), the pilot can determine what to do:

In case of older aircraft, where the altimeter is calibrated in feet, the pilots use a conversion card for determining the altitude in feet, before dialing in the altitude to the autopilot.

Source: aerosavvy.com

Note: The conversion charts are standardized for the airspace and the pilots have to use it. For Chinese airspace refer FAA document on Chinese RVSM

In case of modern aircraft displays, the altimeter can be made to display altitude in imperial (feet) or metric (meter) units.


How much extra work to get a glider licence?

(I am assuming your question is asking about the FAA regulations.)

If you already have a PPL, then the requirements are modest. According to the Soaring Society of America:

  Additional Pilot Rating
  Holders of a valid FAA Power plane license with 40 hours as pilot-in-command need a minimum of 10 solo flights to qualify to take the glider flight test. No written exam is required to add a glider rating to a power license. In all cases, refer to the Federal Aviation Regulations for details on pilot licensing.


How to define quarter-chord sweep angle for a cranked wing?

I think you have to define the sweep angles for every section on the cranked wing. You can use the same definition for each segment as for a "normal" wing. So practically speaking: Root Segment quarter chord --> create line between quarter chord of root and quarter chord of kink. Then you can measure the sweep angle of the root segment. Continue with next segment. The quarter-chord sweep angle is the angle between the y axis and the quarter chord line.


Not really.  That movie had more gags associated with everyday objects eg Capt. Oveur initiates taxiing the 707 by shifting it into gear, like a car, etc.  I don’t really recall any aviation specific elements - aside from that it took place on a commercial airline flight - that only pilots or someone with a deep knowledge of aviation would get.  One aviation item which gets a little overlooked was names of the flight crew - Captain Clarence Oveur (Clearance, Over), FO Roger Murdoch, and FE Victor Boston, being plays on common radio terms “Roger, Roger.  What’s out vector, Victor?”  Another one I recall was a minor scene between Lloyd Bridges and Robert Stack where they argue the pros and cons of letting Stryker do a normal landing vs foaming the runway and letting him land wheels up.  Of course what made that scene funny was the slapstick use of a water cooler.  Bridges had another scene with Stack where Stack remarks “That’s impossible!  They’re on instruments!” which cuts to a scene with Stryker, Elaine, and Dr Rumak playing jazz using musical instruments in the cockpit.  Most of the film’s jokes had to be more relatable to the man on the street’s concept of air travel eg “the White Zone, Red Zone” recordings they used to play, being pestered by religious irritants for money in terminals, etc.  I don’t think Airplane! would’ve have had nearly the appeal if it’s humor was based on a deep knowledge of aviation.


This website has the definition:

  Crosscheck is a generic term used by pilots and flight attendants
  meaning that one person has verified the task of another. In the
  cabin, flight attendants crosscheck one another’s stations to make
  sure the doors are armed or disarmed as necessary.


What is the stick at the bottom of the tail on a ATR-72?

It is a tail stand, also called as pogo stick and is used in the aircraft during loading/unloading. It is basically a stick, which is carried around in the aircraft and attached to the rear fuselage using a pin during loading/unloading operations, as can be seen in the image below.

Air Dolomiti ATR 72-212A (I-ADLS) - Removeable tail stand installed at the rear of the aircraft when it is parked on the ground. In case of weight imbalance, this prevents the aircraft from resting on its tail. By User:Mattes - Own work, Public Domain, Link

It is found in other aircraft like Saab-Scania SF340B etc.

You're right that it must be removed before takeoff to prevent potential structural damage. However, there have been instances where aircraft have taken off with them. There have been other issues too:

  First of all, there have been previous incidents where the ground crew have just tossed the tail stand into the aft compartment and not replaced it into the storage bracket. As a result, the tail stand has gotten jammed into the control cables for the tail surfaces which run through that compartment. ... . The second reason is that being less visible, the built in tail stand would occasionally be left connected to the aircraft on departure creating the potential for structural damage.

Because of this, external metal stools are used in some cases. Of course, the aircraft can be loaded/unloaded without the tail stand by loading the aircraft in appropriate sequence.


What does the runway distance mean under "Additional Runway Information" on Jeppesen plates?

From page AIRPORT-3 (page 3 overall) of this Jeppesen legend (site jump-off page here):


How is the zero-lift drag coefficient calculated?

You can look it up in reference books. For wings, the NASA report server is your friend. For complete aircraft, there is some data available in books about pre-design of aircraft. The one I have is Synthesis of Subsonic Airplane Design by E. Torenbeek, and gives the following numbers for $C_{D_0}$

0.014 - 0.020 for high subsonic jet aircraft
0.018 - 0.024 for large turboprops
0.022 - 0.028 for twin engine piston aircraft
0.020 - 0.030 for small single engine aircraft, retractable gear
0.025 - 0.040 for small single engine aircraft, fixed gear
0.06 for agricultural aircraft without spray system
0.070 - 0.080 for agricultural aircraft with spray system

Appendix F of the same book gives a method for more detailed estimation in the pre-design phase, when no wind tunnel data is available, based on data of the components that make up an aeroplane.


Aircraft structures are required to withstand the structural damage caused by birdstrike. According to 14 CFR 25.571 - Damage - tolerance and fatigue evaluation of structure:

(e)Damage-tolerance (discrete source) evaluation. The airplane must be capable of successfully completing a flight during which likely structural damage occurs as a result of -
(1) Impact with a 4-pound bird when the velocity of the airplane relative to the bird along the airplane's flight path is equal to Vc at sea level or 0.85Vc at 8,000 feet, whichever is more critical;

In case of aircraft with high cruise speed, the speed may be limited below 8000 ft to comply with this regulation. As Bird Strike Requirements for Transport Category Airplanes notes,

... to meet current bird strike criteria, some manufacturers specify relatively low $V_{MO}$ and $V_{C}$ airspeeds up to 8000 feet, that increase above that altitude.

The 'bird strike speed' is likely this.


What are good resources for learning more about communications?

Phraseology is standardized by the ICAO (but countries can notify differences to the standard) in Annex 10 and other documents. The ICAO quick reference guide presents phraseology examples for various situations (taxi, approach, emergency,...). If you are interested in recommendations concerning radio communications in general (not just what directly concerns the pilot), Eurocontrol released a European Action Plan for Air Ground Communications Safety.

Many CAAs also have some form of phraseology reference manual available for free. The general procedures and the phraseology will be almost the same from one country to the next, but variations do occur.

US:

The AIM has a section dedicated to radio communications which details procedures, phraseology and provides general recommendations. Communication examples illustrate the general principles.
The FAA also published an order prescribing ATC procedures and phraseology (but this is a very dry read. Not where I would start)
The Instrument Procedures Handbook contains information regarding radio communication procedures specific to instrument flying (e.g. how to receive a clearance at a non-towered airport)

EU:

Eurocontrol released a guide to phraseology for GA pilots describing good communication practices, phraseology for different flight phases and aviation acronyms. It also has pictures (picture books are always better ;-) ).

UK:

The CAA release a radiotelephony manual describing the phraseology for different flight phases with examples at the end of the manual. It also describes the differences between ICAO and UK radiocommunications procedures (eg FL ONE HUNDRED instead of FL ONE ZERO ZERO).

France:

The SIA has a phraseology training manual with phraseology examples for each flight phase and for using different flight services (ATC, AFIS,...)
The official text for radiotelephony with phraseology in French and English

And many more...

Knowing the phraseology is one thing, but understanding what is being said on the radio can be quite difficult. If you want to practice listening to and understanding radio exchanges, you can find ATC recordings on YouTube or go to LiveATC for ATC communications from all over the world.


What are the climb rates during the different phases of flight of an A320?

According to the EUROCONTROL Performance Database, the usual climb rates and speeds for an A320, for ATM purposes, are those depicted on the image below:

Source: https://contentzone.eurocontrol.int/aircraftperformance/details.aspx?ICAO=A320&ICAOFilter=a320

Note that rate of climb (ROC) is given in feet per minute, not degrees. If measuring degrees, you are talking about the climb gradient, not climb rate.


Since shock waves have non-negligible viscosity, why do the normal shock relations ignore friction/viscosity?

Neglecting friction does indeed lead to inaccuracies. Those, however, are small for weak shocks, so using the equations for inviscid shocks gives a good approximation. Especially in the times before electronic computers, this was a major simplification while the error was tolerably small.

Stronger shocks should be avoided and replaced by a cascade of weaker, oblique shocks in order to minimize losses, so for practical work there is little need for equations which include those losses. Only in academic work and the design of reentry vehicles with their blunt geometries would the precise calculation of stronger shocks be of any interest.

But how large are those losses? Wikipedia has a page on normal shock tables and the last column gives the ratio of the stagnation pressures ahead and past the shock. Since both should be the same in case of a lossless shock, the real number gives a good approximation of the energy losses incurred over the shock. The more the result deviates from 1, the bigger the losses. 1% of stagnation pressure is lost at a Mach number ahead of the shock of approximately 1.225. 10% is lost at Mach 1.587. It goes down from there: 50% is lost at Mach 2.5 and 90% at Mach 4.4. All values use a ratio of specific heats of 1.4, so they are valid for a two-atomic gas (or a mixture of predominantly two-atomic gasses like air).


Is it possible to lift a ship sized vehicle into the sky by following modern day aerodynamics and aircraft design?

Possible: Yes

You can in theory lift anything. To do this you will simply need to generate an equal or exceeding amount of lift than the weight of the object. You will also need to generate enough thrust to achieve said situation. The closest thing I can think of to this was Howard Hughes Spruce Goose which did actually fly. If you are talking about the kind of vertical hovering that the ship in the movie does you would need to generate an amazing amount of thrust to achieve that. A US Nimitz-Class aircraft carrier displaces 100,000 long tons (224,000,000 LBS) so you would need to generate at least that much thrust but in reality you would need to generate more to overcome drag and to actually accelerate the craft vertically. For a point of comparison the Saturn V rocket weighed 3270 tons (6,540,000 pounds).

If we work through a quick example (these are very very lose numbers), lets take the Nimitz at 224,000,000LBS and the GE90 jet engine (currently the biggest turbo fan jet). The GE90 generates about 115,000 lbf of thrust. So it would take just under 2000 GE90s to generate enough thrust. But lets round it off at 2000 for ease of use and a bit of extra power. The diameter of the engine is 3.429m and the Nimitz is 332.8m long. You would need arms with 10 engines a piece just to make all 2000 engines fit down the length of the side. If they were stacked directly next to each other the arms would be about 35m in length. The bigger issue here is fuel flow/mass. You would need to lift enough fuel to actually power these engines for a useable amount of time.

On the more sifi side of things, you could use the Nimitz's nuclear reactor to power ducted fans which overcomes the fuel problem to an extent but I dont have any numbers on that.


How do pilots avoid clouds under night VFR?

I will caveat my answer by saying that most of my night flying has been under IFR, but because of that I have lots of experience going in and out of clouds at night.

It starts with a good weather brief, and don’t forget to ask for PIREPS that might cover areas further away from the field.  True enough the bases can be ragged, and little puffies can lurk in unexpected places, but if you know where the layers are called you are well on your way to avoiding being at the same altitude.

To add to one of the comments, moonlight is helpful, but so is ground lighting.  At night distant clouds can be difficult to see, but you can use ground lighting to gauge where the coverage is.  For example, if your eyes can trace a lighted road off in the distance, but at approximately 20 degrees below the horizon the car lights become blurry, then disappear, it is probably because of a cloud between you!  Angle away, or descend below the deck until the horizontal visibility range increases.

If you start skimming clouds you will know it immediately because your anti-collision light will blossom and reflect red all over the inside of the cockpit.  If you still have ground lights in sight and you know the clouds are stratified, I would start a gentle descent.  If there are a lot of vertical buildups and you pop into one and lose sight of the ground, make a level 180 and get out of there.  Most non-instrument rated pilots are taught to deal with inadvertent IMC in this way.

As I mentioned in my answer to your other question, make sound risk decisions.  If you are uncomfortable with the weather conditions or your ability to remain clear of clouds, then choose to not fly VFR at night.  But once you get a few night flights under your belt I think you will find that they can be very enjoyable when conditions are good.  It opens up a whole new perspective on things!


They want to know how deep is your general understanding of W/S.  My answer would be, "What kind of wind shear are you asking about?  Microburst from a thunderstorm cell? Descending through a nocturnal jet (large change in wind velocity at a few hundred feet at night)? Wind shadow shear just above the surface?" (it's not unusual in a jet to hit a little 5 to 10 knot shear at between 100-200 ft when landing, just from the effect of trees and buildings slowing down the surface layer of air) and go from there, based on the research I've down beforehand.

There is no time limit. Could be 5 seconds. Could be half a minute, the time it takes to cross a mile wide microburst at 120 kt.  Whatever. The key thing is to do some googling and read some articles on windshear so you can sound like you've taken the trouble to learn about the topic.

So don't just look up that specific answer.  Become knowledgeable on the phenomenon itself.  That's what they want to see.


Why are Western helicopters more expensive, yet smaller in size, but Russian helicopters are way less expensive, and larger in size?

It's just market.
Like most markets, it's not even entirely rational. In the end, people may just have preferences. It commonly happens that a car X is cheaper than Y (and/or depreciates more), despite being better on every objective measure as a vehicle. But on the Y's side may be long-term reputation, familiarity, etc.
Still, there are many perfectly rational reasons for such disparity (lower cost of Russian aircraft), particularly in the West.

Service cost and, even more importantly, its availability. Russia is not particularly renown for its after-sales service, even within the country. A grounded aircraft is a big money drain.
Likewise, availability and cost of pilots for such less common aircraft. This includes training, licensing them etc.
Typically higher fuel consumption per unit payload (for the same generation of aircraft).
Typically smaller service intervals and shorter overall lifetime. This is partly due to military origin of most Soviet/Russian helicopters.
Depreciation and later sale prospects. This is somewhat a vicious circle, but it's an important factor affecting purchasing decision.


Can a Boeing 747 take off fully loaded on 3 engines?

The short answer as detailed to some degree in previous answers and comments is that a 747 can takeoff if the engine fails after the V1 speed is reached but not if the failure occurs before reaching V1. Unfortunately, in my opinion, the owner of one of the answers has deleted his answer, which while perhaps imperfect did provide useful information, and perhaps as important will remove the comments.
It's best to understand the V1 speed within the context of a balanced field takeoff. See this Wikipedia article for a full explanation. The first two paragraphs are:

A balanced field takeoff is a condition where the accelerate-stop distance required (ASDR) is equal to the takeoff distance required (TODR) for the aircraft weight, engine thrust, aircraft configuration and runway condition.1 For a given aircraft weight, engine thrust, aircraft configuration, and runway condition, the shortest runway length that complies with safety regulations is the balanced field length.
The rejected takeoff initial actions speed V1, or critical engine-failure recognition speed (Vcef),is the fastest speed at which the pilot must take the first actions to reject the takeoff (RTO). At speeds below V1 the aircraft may be brought to a halt before the end of the runway. At V1 the pilot must continue the takeoff even if an emergency is recognized.

Let's translate this into a practical situation using a 747-200 with old steam gauges. Prior to engine start five plastic bugs would be positioned around the rim of the airspeed indicator: the first at V1, the second at VR, the third at V2, and the last two at speeds not relevant to our discussion. We're rushing down the runway at takeoff power and all goes well. When we reach V1, the PNF says "V1" and the PF takes his hand off the thrust levers (he had them there in case of an abort). When we reach VR, the PNF says "rotate" and the PF brings the yoke back briskly but smoothly to a pre-determined nose attitude (usually 12 or 13 degrees). When the landing gear is off the runway, you'll hear the gear down lock retract unlocking the gear up lever. When the PNF sees a positive climb rate on the vertical speed, he'll say "positive rate", the PF will call "gear up", the PNF will move the gear lever to up. When the airplane reaches V2 the PNF will say "V2".
The important thing to remember here is that if there had been an engine failure after V1, the only difference would have been that the first person to know which engine had failed would have called "engine failure #1" say. On the old 3-crew airplanes, that would usually be the f.e. Even if the engine was burning, no action would be taken until after V2, and probably not until after you had a clean airplane.
Just as a matter of information, here are some V speeds for a 747-200 with P&W JT9D-7Q engines for a Flaps 10 takeoff at 840,000 lbs:

V1 168 kts
VR 181 kts
V2 189 kts

Now for an abort. An abort below 80 kts is no big deal. Between there and 100 kts gets more interesting. Above 100 kts it is not to be taken lightly, and an abort at say, 150 kts, is a bonafide emergency. A friend of mine had to do one of those, and he blew all of the 16 tires that had brakes. In my view, if an engine failure occurs within a few knots either way of V1, you're better off flying.
To quote from an accident report in which I was involved in the investigation:

The bang and the loss of power occurred around V1 speed. Two seconds after the bang, all four engines were brought back to idle, and braking action was initiated. The thrust reversers were not deployed.
The aircraft came to a stop 300 m after the end of runway 20, above a railroad embankment. The aircraft was severely damaged; it broke in three parts.


I think you are making things too complicated on yourself. To the best of my knowledge, fighter jet controls will in principle behave the same way as almost any other aircraft- they will in general actuate surfaces the same regardless of orientation. A left/right movement controls roll, a backwards/forwards movement controls pitch.

You would push the stick sufficiently to the right to bank until you reach the desired turn rate. You would have to maintain a little right stick to maintain the bank angle.
As you do the above, pull back a little to ensure that the vertical speed remains zero. You also need to add a little rudder to create a coordinated turn.

See the following images taken from here and here:


What is significance of N1 and N2 in Jet engine?

Compressor and turbine are connected by the same shaft. You have LP compressor+turbine and HP compressor+turbine. For Rolls Royce engines you have N3 too because they use three rotors instead of two.

N1 or N2 show the percentage of rpm for the respective shaft. Each engine has a particular number of rpm corresponding to 100% N1 or N2 in order to make numbers easier to understand for pilots between different engines.


What does a dot inside two parenthesis mean on a weather depiction chart?

From here, $(\cdot)$ means that there is precipitation within sight, reaching the ground, not at the station, but < 5 km from the station.

$)\cdot($ means that there is precipitation within sight, reaching the ground, not at the station, but > 5km from the station.

This source and this source give similar definitions, but without a strict distance cutoff, instead just saying "distant" and "near".

I couldn't find any references to this symbol in Nav Canada's weather code and symbol legend.


Is there a such thing as an ARINC label for the yaw angle?

Non-authoritative list of some labels:

ARINC 429 Labels

But labels are not all defined in ARINC standard, a specific LRU can define custom values. So you need to get label list from LRU documentation. For instance, labels used by Laseref VI IRS to output values to the bus are:

Source: Honeywell

Your question is ambiguous about what you are looking for: Yaw is the rotation around an axis normal to the plan defined by longitudinal and pitch axes. The origin can be multiple:

It can be seen absolute, for instance referenced to the north, and it would be the heading. It can defined relatively to a given direction, e.g. the wind, and it would be computed from other values. More likely it can be a rate.

Here are some related labels:

Yaw rate = 330
Heading: True = 314, Mag = 320
Track angle: True = 313, Mag = 317
Wind direction: True = 316

(octal values)

Could you provide details about your needs?


Why do some aircraft require type ratings to fly them?

The FAA specifies the airplanes that require a type rating in 14 CFR 61.31:

  Sec. 61.31 - Type rating requirements, additional training, and
  authorization requirements.

  (a) Type ratings required. A person who acts as a pilot in command of
  any of the following aircraft must hold a type rating for that aircraft:

  (1) Large aircraft (except lighter-than-air).
  (2) Turbojet-powered airplanes.
  (3) Other aircraft specified by the Administrator through aircraft type certificate procedures.

So in short, large aircraft (meaning that they weigh more than 12,500 lbs.), aircraft having turbojet engines, or any airplane deemed suitable complex that it needs it by the FAA need a type rating in order to fly it as PIC.


Why aren't passengers instructed how to lift aisle armrests?

The FAA provides some useful links in their cabin safety index document here. It seems according to this document, as well as this bulletin arm resets (in general) may actually provide a bigger safety risk when lifted and that they should be placed in the down position for takeoff and landing for emergency reasons:

  3-3484 PROTRUDING PASSENGER SEAT ARMRESTS. Inspection of the Hardman Model 9500 and other passenger seats installed on several
  aircraft disclosed that the armrest in the upright or stowed position
  can protrude approximately 45 degrees aft the seatback. In the event
  of an emergency evacuation, protruding armrests could present an
  obstacle between seat passageways, obstructing emergency exit access.
  Air carriers should emphasize to F/As that prior to takeoff and
  landing they verify that the armrests are in the normal forward/down
  position in order to ensure that they do not obstruct the passageway
  between the row of seats leading from the aisle to the emergency exit.

Also it would seem that according to §382.61   What are the requirements for movable aisle armrests? the movable arm rests are mainly there to allow the easier seating of those with limited mobility and not intended to aid in evacuation.


What is the EASA definition of night time?

According to this handy document from EASA, night is defined as:

  …the period between the end of evening civil twilight and the beginning of morning civil twilight, or such other period between sunset and sunrise as may be prescribed by the appropriate authority, as defined by the Member State.

(The FAA and ICAO use a similar definition.)

You can get the Civil Twilight times from a convenient astronomical calendar, but ignoring the specifics, the same rule of thumb the FAA uses for purposes of night currency will likely work for you too:

Night starts one hour after sunset
(Sunset being when the last of the visible sun disc drops below the horizon.)
Night ends one hour before sunrise
(Sunrise being when the first of the visible sun disk breaks the horizon.)

This actually cheats you out of a few minutes of "night" on either side of the calculation, but it's conservative guidance if you're conservative in what you log you won't accidentally mess up and give yourself more night time than you're really entitled too (i.e. you won't make yourself "night current" when you really aren't).

Note that I'm a US pilot -- since all my flying and training is based on FAA regs in the US if I'm completely off the mark and any European pilots or CFIs want to set me right it would be much appreciated :-)


Yes.  See FAR 119.1.  They have a list of other commercial operation you can do with a CPL but not an ATPL.


Can someone provide details about airlines dividing crew into personality groups?

I spoke to my friend at the one of the ME3 carriers. She tried to find any information regarding this matter but was not able to find it. However during your recruitment process you have to perform a personality test and based on this test you are placed in one of the total of 7 groups. During the scheduling they combine people from different groups so that there is a balanced and workable crew on board. Say that you're in group 5, then you will for example mostly work with people that are in group 1 and 3.
Questions on this personality test are like:

Would you rather (example: clean a room or work within a group)
Which statements best describes you? (leader, selfish, friendly, etc, etc)

These airlines are run on performance optimization and care less about human values.


How do planes benefit from flying in formation?

Energy saving

The wing creates lift, which is upward force on the wing. According to principle of action and reaction, there must be a downward force acting on the air. This force creates a downwash behind the wing. As the accelerated air interacts with the still air further away it turns to the sides and back up, creating a slight upwash outside of the wingtips.

Flying in this upwash adds a bit of lift on the next flying thing which in turn means it can fly at slightly lower angle of attack and have less induced drag. This recovers some energy from the wake vortex that would otherwise be dissipated as heat.

Birds

Migratory birds use the typical V formation to take advantage of this, each bird flying aft and to the side of the previous. Since the leader is not getting any advantage, the birds usually take turns in leading the flock.

Aircraft

I have however not heard of this being done with aircraft for energy purposes beyond experiments. Military aircraft usually use similar V formation, but for different reasons. They need to fly in group, because they need to provide mutual defence. And then the V formation is used during cruise to and from target area simply because in it the wingmen see the leader while remaining clear of their downwash and wake turbulence.


What happens when all passengers jump at once?

I will assume that the starting condition is level flight.

yes. momentarily the assumption of "rigid body" would not be satisfied. Also, for that 0.5s the aircraft would not be in contact with 10% of the weight, assuming constant thrust and velocity, you would have 10% more lift than weight, making the aircraft rise a bit before descend again when all the passengers land again. Velocity would not be greatly affected, as the drag would remain unchanged (no external change in shape or large attitude variations)
the difference between zero-fuel weight (ZFW) and Dry Operating weight (DOW) is probably what you are looking for. Airbus defines it as the "total traffic load". If you want to add catering, cabin equipment and the crew, you then take the difference between the ZFW and the Manufacturer's Empty Weight (MEW). As a percentage it can vary wildly based on the aircraft class (class 23 has much less cargo/passenger space that a class 25, for example)
yes. think of a beam in equilibrium on a pivot located at half its length: if you push just above the pivot, the beam will not rotate, any other location will cause it to rotate and flip over. This does not mean that the aircraft might flip over, as the beam is an uncontrolled and unstable system, while the aircraft is controlled, but it is a comparison that can help visualize the effect
I would define it more as shifting rather than jumping. This is a totally different scenario: the center of gravity at the end of this "jump" would be in a totally different location w.r.t. the start of the experiment, something that instead was not happening in the previous scenarios. By shifting the location of the center of gravity is likely that it might exceed the specified position limits and cause the airplane to be uncontrollable, to pitch up or down (depending if you shift the passengers backwards or forwards) and stall or nose-dive. On large aircrafts it is obviously not easy to achieve such unsafe scenario, as the cargo will be usually much heavier than the passengers, limiting the extent of the CG shift.


Are there helicopters with vertically mounted turbines?

Discounting the V-22 Osprey and the other tiltrotors, the drawbacks are:

Wasted cabin space
L-duct inlet(s) needed to guide the air in
With that potential problems with getting the air in as the air prefers fewer turns
A reduction gearbox is still needed
Gearbox still needed for the tail rotor
Harder maintenance access as it will be buried into the fuselage
If the exhaust is channeled downwards: potential tarmac melting, fuselage weakening, and handling issues in low hover
If channeled upwards, well, that's where the rotor is
Otherwise, extra heat ducting needed, i.e., added complexity and weight and expensive materials
Any fire or uncontained failure will cause grave danger.

Below is the best illustration I could find, and it gives you an idea about the previous points:

http://www.melm-md.com/images/N600_image_02.jpg


In helicopters, why not have electric motors controlling blade pitch?

How would you communicate with (and power) these motors?

The main rotor is spinning constantly - Wires won't work, they would wrap around the shaft and be shredded. A slip ring and brushes (as used in some electically-actuated propellers) would work, but would also wear away quickly and require frequent maintenance as losing control of a helicopter's main rotor blade pitch is a much more serious situation than losing control of a fixed-wing aircraft's propeller pitch (I believe this captures the consequences pretty well).
Because of the rotor speed balance is critical, so any motors, brushes, etc. would need to be balanced around the rotor hub (either by duplicating the equipment, which also provides redundancy, or by adding dummy weight) - get it wrong and the rotor starts vibrating and may come apart.

The motor would also have to be constantly moving: The swashplate adjusts blade pitch through the full 360 degrees of rotation, smoothly changing the pitch of each rotor blade as they rotate. Duplicating this would require the motor(s) to make constant adjustments as the rotor turns, moving and reversing very rapidly). The level of precision required and the forces involved would likely require high-torque stepper motors and a computerized control system of some kind would be needed to drive them and make the necessary blade pitch adjustments at "rotor speed".

So far the motorized solution has added at least one motor, a slip ring & brush system to communicate with it, and a fly-by-wire computer to read the flight control positions and appropriately adjust the blade pitch through 360 degrees of rotation (at whatever speed the rotor is operating).
That is already a lot of complexity and a substantially increased chance of failure versus the (relatively) simple mechanical solution of a swash plate, and I'm not even going out of my way to think of failure modes (actual engineers designing these things are far more paranoid, and could probably imagine all sorts of failure scenarios which eventually result in a helicopter plunging to the ground).


It contains the evacuation slide. From airspacemag:

  An escape slide sits inside a carbon fiber pressure cap covered by a casing of material similar to the aircraft interior walls—that big square box at the bottom of an airliner’s interior door.

Here's an image from Boeing:

Image from Boeing.com

According to Boeing, the positioning of evacuation slides inside the doors reduced the deployment time.

  By 1963, improvements in materials and inflation systems reduced the weight and bulk of the slide system, making it practical to move the slides out of the ceiling to the lower inboard face of the cabin doors (see fig. A). This location resulted in a still more efficient escape system, reducing the time needed to ready an escape slide from between 20 to 50 seconds to between 18 and 24 seconds, including door opening time.


Can lift be increased by increasing the angle of incidence of the wing?

Yes.  Angle of Attack is included in the Lift formula.  Lift generally increases with angle of attack in a linear fashion until AOA reaches stall.  This is why it is not a good idea to fly at too high an AOA.  Better to increase Velocity.  Lift increases with Velocity squared.

The Navy Vought F-8 Crusader had a "variable incidence wing" that was raised to a higher pitch relative to the fuselage for take-off and landing.  Interesting to note the variable incidence wing would also improve forward visibility on landing because the fuselage nose would have a lower pitch to the horizon while the wing was at a given angle of attack.  Trailing edge flaps also raise the wing chord incidence to the fuselage with similar benefits.

While in flight, most planes simply pitch the entire plane with the elevator to increase Angle of Attack.


How close is a pilot allowed to get to a runway without landing clearance?

From the Pilot/Controller Glossary:

  CLEARED  TO  LAND−ATC  authorization  for  an aircraft to land. It is predicated on known traffic and known physical airport conditions

A clearance to land is exactly that: a clearance to land. A pilot without landing clearance hasn't violated ATC instructions until their aircraft has, in fact, landed. So the answer to how close you can get is: anything that isn't touching the surface.


Are ETOPS rated planes denoted by a placard or other indicator?

According to FAA §25.1535 Appendix K,

  The airplane flight manual must contain the following information applicable to the ETOPS type design approval:

  (b) Required markings or placards.

  (e) This statement: “The type-design reliability and performance of this airplane-engine combination has been evaluated under 14 CFR 25.1535 and found suitable for (identify maximum approved diversion time) extended operations (ETOPS) when the configuration, maintenance, and procedures standard contained in (identify the CMP document) are met. The actual maximum approved diversion time for this airplane may be less based on its most limiting system time capability. This finding does not constitute operational approval to conduct ETOPS.”

It does not require any identification marking on the aircraft itself, though as @woakley5 noted above, a number of aircraft do have them identifying the aircraft as ETOPS certified, like below.

Source: www.thaiflight.com

I'm not sure about if any indications are there in cockpit (there are no regulatory requirements, till today that is), but won't be surprised if it is available (in some aircraft, at least).

The ETOPS do have some additional checks. According to Appendix G to Part 135,

  (This) This ETOPS maintenance program must include the following elements:

  (b) ETOPS pre-departure service check. The certificate holder must develop a pre-departure check tailored to their specific operation.

  (1) The certificate holder must complete a pre-departure service check immediately before each ETOPS flight.

  (2) At a minimum, this check must:

  (i) Verify the condition of all ETOPS Significant Systems;

  (ii) Verify the overall status of the airplane by reviewing applicable maintenance records; and

  (iii) Include an interior and exterior inspection to include a determination of engine and APU oil levels and consumption rates.

I'm not sure how the AA Flight 31 Flight and ground crew missed these checks.


What fighters have both 1 & 2 engine versions?

The Republic F-84F Thunderstreak was a fairly normal early jet fighter, powered by a single Wright J65 turbojet engine.

Its mutant offspring, the Republic XF-84H "Thunderscreech" was a experimental turboprop fighter, powered by an experimental Allison T40 engine, which consisted of two Allison T38 engines, joined through a common gearbox.

This was a twin-engine aircraft from the maintenance point of view, since there were two sets of turbo-machinery to go wrong. It looked like a single-engine aircraft, and flew like nothing on earth, owing to the strange effects of two sets of supersonic shockwaves from the contra-rotating propellers hitting the wings several times per second. Its first test pilot refused to have anything more to do with it after the first flight; the second test pilot flew it eleven times, but Republic did not submit the aircraft for USAF trials.

Edit: The reason for doing this was that early jet engines were very fuel-thirsty, while turboprops got much better mileage. The propeller was supersonic because that was necessary to absorb the power in a small enough propeller to fit within the aircraft's ground clearance. It wasn't remotely a good idea, but it may have shown the USAF that jet-age aircraft development was harder than it had been in the piston-engine era.


Does a military equivalent to civil ATC exist?

Yes, for their airspace.

Generally speaking, US Military has its own ATC for domestic military installations and other venues such as US Navy aircraft carriers. Most of these military-staffed airports are rarely transited by civilian aircraft, and are instead designed to let the military run their own show with their own aircraft.

At some airports around the country which provide provide joint military-civilian use, such as Charleston Air Force Base in South Carolina, Scott Air Force Base in Illinois, and Marine Corps Air Station Yuma in Arizona. These airports have significant military traffic and also allow civilian aviation operations. At such airports, typically FAA controllers are in place and military aircraft work with them.

Most of the airspace in the US is owned by Air Route Traffic Control Centers, which are staffed exclusively by FAA-employed civilian controllers. These controllers handle all air traffic between airports, including military aircraft transiting the national airspace system, which means that civilian and military facilities all around the country must interact with each other on a daily basis. As a result, both civilian and military air traffic controllers use a commonly shared phraseology.

For exclusive military use, there is special use airspace which includes:

  ... restricted airspace, prohibited airspace, military operations
  areas (MOA), warning areas, alert areas, temporary flight restriction
  (TFR), national security areas, and controlled firing areas, typically
  up to FL180 or 18,000 ft above sea level.

Source

As discussed in this question, supersonic operations in the US are also performed in airspace which belongs exclusively to military.


What is the effect of airflow speed on separation?

In a subsonic flow, the separation point moves downstream as Reynolds number increases, and Reynolds number increases with free stream velocity.

Demonstration on a cylinder-shaped airfoil:

Source

From Wikipedia:

  Reynolds number is the ratio of inertial forces to viscous forces
  within a fluid which is subjected to relative internal movement due to
  different fluid velocities

Separation occurs at the location the laminar airflow stops being accelerated, and is decelerated by areas of upstream turbulent airflow in separation bubbles created by friction (viscosity):

Source

Velocity gradients in the boundary layer at different points in the transition area where the flow transitions from laminar to turbulent:

Source, adapted

Velocity is decreasing near the surface due to friction, and at some point becomes negative. Separation bubbles appear between the laminar flow and the airfoil. In a bubble there is a secondary reverse flow and a region where air is stagnant. Downstream the bubble, air is turbulent:

Source, adapted

While other elements affect the boundary layer separation point, this one is the largest. To counter this effect, the momentum of the laminar stream must be increased relatively to frictional forces. This is done (by definition) by increasing the Reynolds number, e.g. by increasing the airspeed.

Increasing airspeed can be obtained by accelerating the aircraft, but also by other ways. For example, different devices are used to delay the separation of the boundary layer when the aircraft must be slowed down. It consists on accelerating ("re-energizing") "dead air" near the surface, e.g. using high speed jets or vortex generators.

This is for instance the principle behind slats and slotted flaps:

Source, adapted

The boundary layer separation is due to flow deceleration as it moves away from the leading edge and an adverse pressure gradient appears (potential flow theory).

The lower energy flow is more prone to perturbations, vortexes appear and disappear, increasing in importance. Portions of vortexes have a velocity opposed to the free stream velocity, this creates areas of "dead air". Viscosity takes over inertia. This ratio between inertia and viscosity effects is the very definition of the Reynolds number.

By increasing velocity (actually the Reynolds number), this effect is minimized: The separation point moves downstream, as the effects of the adverse pressure gradient are countered on a longer distance as visible on the velocity gradients shown on the flap/slat picture above.

Flaps/slats have the additional advantage (over vortex generators for instance) of increasing the wing surface, hence restoring lift lost when the airplane was slowed down.


How does fuel efficiency depend on wing configuration?

The largest losses on a wing usually occur at the tip, where high pressure air flows around the end from the underside to the top side. This can be minimised by making the wing longer and thinner, or tapering it so the tip is smaller. You can also add winglets to reduce tip losses, but they're tricky to get right.

If you fly near the speed of sound, you get shockwaves that cause a lot of extra drag. You can slightly raise the point where they become a problem by sweeping the wing, and wing sweep also helps to reduce the drag when you are supersonic - but supersonic is never an efficient choice.

Drag is proportional to speed squared, so if you just want to fly for as long as possible, it's most efficient to fly slowly. However if you want to cover distance it's more efficient to fly really high where the air is thin.

You can put all this together to get an airliner, with a long, thin, highly tapered wing (and winglets), flying so high that the air is only just dense enough to support it, and just below the speed that shockwaves cause extra drag.

You ask about wing position, and there is some interference drag where two surfaces meet. It is minimised by making the angle between the two surfaces as large as possible. Thus a mid-wing is slightly more efficient than other designs, but it's a relatively small effect. Wing position is usually determined by the undercarriage design and the pilot's field of view.


What is the difference between a MEL, MMEL, KOEL and Equipment List?

Definition of Master Minimum Equipment List from ICAO Master Minimum Equipment List/ Minimum Equipment List Policy and Procedures Manual:

“Master Minimum Equipment List” means a document approved by the Director General that establishes the aircraft equipment allowed to be inoperative  under conditions specified therein for a specific type of aircraft.
A Master Minimum Equipment List (MMEL) is an approved document created specifically to regulate the dispatch of an aircraft type with inoperative equipment. It establishes the aircraft equipment allowed to be inoperative under certain conditions for a specific type of aircraft and still provide an acceptable level of safety. The MMEL contains the conditions, limitations and procedures required for operating the aircraft with these items inoperative. The MMEL forms the basis for development and review of an individual operator's  Minimum equipment List (MEL).

Definition of Minimum Equipment List from the same document:

“Minimum Equipment List” means a document approved by the Director  General that authorizes an operator to dispatch an aircraft with aircraft  equipment inoperative under the conditions specified therein.

and

The MEL is a joint operations and maintenance document prepared for or by  an operator to:
a) identify  the minimum equipment and conditions for an aircraft to maintain the Certificate of Airworthiness in force and to meet the operating rules for the type of operation;
b) define operational procedures necessary to maintain the required level of safety and to deal with inoperative equipment; and
c) define maintenance procedures necessary to maintain the required level of safety and procedures necessary to secure any inoperative equipment.

Regulatory authorities use similar definitions. For example, Transport Canada uses nearly the same definition, replacing 'Director General' with 'minister'. So the ICAO definition can be used as the base.
Kinds of Operation Equipment List (KOEL) are lists one finds in some aircraft POH that indicates what equipment (generally optional) si required for flight under certain conditions. From FAA Advisory Circular Minimum Equipment Requirements for General Aviation Operations under FAR PART 91 AC NO: 91-67:

Kinds of Operations List (KOL). The KOL specifies the kinds of operations (e.g., visual flight rules (VFR), instrument flight rules (IFR), day, or night) in which the aircraft can be operated. The KOL also indicates the installed equipment that may affect any operating limitation. Although the certification rules require this information, there is no standard format; consequently, the manufacturer may furnish it in various ways.


What are the units for the bearing to center of an airport from radio aids to navigation in chart supplement?

It's almost certainly magnetic. Page 12 of the Chart Supplement (sample airport information) has this information at the bottom (emphasis mine):

All bearings and radials are magnetic unless otherwise specified. All
mileages are nautical unless otherwise noted.
All times are
Coordinated Universal Time (UTC) except as noted. All elevations are
in feet above/below Mean Sea Level (MSL) unless otherwise noted.
The
horizontal reference datum of this publication is North American Datum
of 1983 (NAD83), which for charting purposes is considered equivalent
to World Geodetic System 1984 (WGS 84).

Because this information is in a kind of footnote at the bottom of the page, I suppose you could say that it's possible it only applies to that specific page. However, the mention of "this publication" strongly suggests that the information applies to everything in the Chart Supplement.
You can also see that it distinguishes bearings from radials, meaning that it's highly unlikely that the word "bearing" is being used to mean "radial" on p.27.


Why would a flight from North America to Asia sometimes fly over the Atlantic?

Those routes are extremely similar.

They're basically two almost-a-straight-line routes over the arctic ocean, except that the second one has deviated a bit to the right, so that it's gone just on the right of the North Pole instead of passing by the left. At the pole itself, there's no such thing as "East" or "West", and if you pass very close to it, there is a discontinuous jump between passing it "going East" and "going West".

You can see this explicitly by going to FlightAware, asking to View track log, and downloading the flight tracking data to be viewed on Google Earth:

 Actual tracking data in white. Interpolations for the missing-data parts in green.

As you can see, there is indeed a nontrivial deviation of what's probably several hundred kilometers in clipping Nunavut vs the northeast corner of Greenland, but that deviation is within the normal ranges of what you'd get in your standard transatlantic flight, say. The only change here is that the variation now includes the North Pole itself.


Is it possible to use variable wing geometry on a fifth generation stealth fighter?

Of course it is possible. But it does not improve the outcome.

Swing wings were a fad of the Sixties. They never fulfilled their early promises, because the actuation mechanism is heavy. Variable sweep is only justifiable when the aircraft will fly both sub- and supersonically for extended periods. It turned out that the part of most missions which is spent at supersonic speeds is a lot smaller than anticipated in the Sixties. Just take the Rockwell B-1: Designed for supersonic penetration (B-1A) it became a subsonic low-level terrain following strike aircraft (B-1B).

For stealth, edge alignment is an important design principle. Making wing sweep variable is to throw this overboard, compromising the whole strategy of stealth. Also, the best stealthiness is only possible in subsonic flight - airframe heating at supersonic speed will broadcast the aircraft's presence to everyone with a low-cost infrared sensor.


Why does Chicago O'Hare have a penalty box?

In addition to what vasin mentioned in his answer, a mechanic from O'Hare mentioned hearing ATC direct aircraft to go there when they weren't ready for takeoff by the time they got to the runway in a comment on the video that prompted the linked question:

  They [the pilot of the aircraft not yet ready for departure] sheepishly called and told the tower that they'd need another moment or two before takeoff. The controller goes..."Uh....yeah, no.....cross Runway two-seven left and hold in the penalty box. We'll be in touch."

Apparently ATC doesn't like you holding up the line of departing traffic at ORD.

As mentioned in the comments, the concept of having a paved area on or near the taxiways for planes to park while waiting to be ready for departure, waiting for a gate, or other similar uses is not unique to O'Hare. Most significantly-sized commercial airports have such areas. The primary thing that is unique about O'Hare's is just that it's named and the name is on the airport diagram. And perhaps also this particular controller's snarky sense of humor.


From the picture I can see a bulk head forward of the telescope area. This modified 747SP might have a re-positioned bulk head then. Anything forward of the telescope would be pressurized.

This source confirms, bulk head was moved from the aft to be ahead of the telescope.


How serious is an impact like the 10/2017 Delta Airlines suspected bird strike?

Bird strike happens all the time - almost on a daily basis. See avherald : there are 9 instances of bird strike in the past 7 days at the time this answer is written. Usually it is ingested into the engine (which usually turns out to be a non-issue), other times it impacts the cone or leading edge of the wings or knocks off a pitot tube.

While a few incidents make it to mainstream news from time to time, bird strikes are a common occurrence in the aviation industry. It is an unusual situation, but not a dangerous situation if the pilots handle it properly.

How severe if it collided with the windshield? The windshield is tested against this type of impact during certification. At worst the outer layers will crack, and the pilot will execute the landing using the "cracked windshield" procedure (Yes there is a procedure written for this scenario).

A note about the UFO: technically it is an UFO, an Unidentified Flying Object. It could be a bird, a drone, weather balloon etc. Examination of the impact area might reveal what the object was.


For jetliners, how is a swept wing justified over a thin wing?

Yes, sweep makes a wing heavier and less efficient. But making the airfoil of a straight wing thinner runs into diminishing returns and also will drive up mass.
Since a thin wing needs to create the same lift as a thicker one, only the local speed increase from thickness can be tackled by making the airfoil thinner. The speed increase necessary for lift creation needs to be maintained, so the thickness contribution becomes a minor factor for the wings. However, a thinner wing requires a heavier spar to carry the same lift loads, so more lift needs to be created by the thinner wing to carry that extra weight. Now further thinning will drive up the speed increase from lift which will eat up the gains from thinning the wing.
If you look at parametric weight equations for airliner wings, the relative thickness at the wing root $\delta$ is part of them and generally occurs in a factor like
$$m_{Wing}\propto\frac{1}{\delta^{\,0.36}}$$
Now it is important to stress that this is valid for the range of thicknesses from which that relation had been derived, something between $\delta$ = 14% and 16%. If you drop below 14%, the exponent will most likely go up since the mass of the spar alone should be proportional to $\frac{1}{\delta}$ and becomes more dominant the thinner the wing becomes. But if root thickness is decreased from 15% to 14%, that means we stay within the limits of the statistical model, the wing mass increase should be 2.5%.
The same model gives the influence of sweep on wing mass as
$$m_{Wing}\propto\frac{1}{cos\varphi^{\,0.57}}$$
Based on 40° wing sweep, every decrease in spar thickness of 1% requires a sweep decrease of about 2.9° in order to keep wing weight constant, based on that relation. If that 1% thickness decrease allows you to desweep the wing by 3° or more, you come out ahead.
As always, a compromise is the best solution. Airliners of the propeller era had thicker wings than jet airliners. Some sweep and some thickness reduction will allow to push the critical Mach number to the highest value. Tank volume is indeed an important factor and is responsible for the comparatively low aspect ratios of early jet airliners.


Is the old paint removed before applying a new one?

Yes, paint imposes a significant weight penalty on larger aircraft. On commercial airliners, that weight translates to a reduction in cargo, passenger and fuel carrying capacity, and that means less money to be made on every flight. That is why some airlines have chosen to remove most of the paint and opt for the bare-metal look. However, there are tradeoffs to be considered, such as the fact that bare metal is much more susceptible to corrosion.

These days removing paint from an aircraft is a relatively straightforward proposition if you know what you are doing. There are a number of environmentally-friendly paint stripping chemicals available that when applied to the aircraft surface, cause the paint to bubble and lift off the underlying airframe.

The paint can then be scraped off with plastic tools or removed with a pressure washer, and the stripping chemical is washed off. Other products are then used to clean remaining residue, treat the metal for corrosion protection, prime and paint.

This explanation is intentionally simplistic, but it covers the basics to answer your question. If you want to see the process in action, you might check the many YouTube videos that show time-lapse recordings of aircraft being painted. Personally. I think they are fun to watch. :)


How do I pick the right ATC channel to listen to my flight?

As you would have noticed, it's not published which frequencies your flight will use. So it requires dedicating some time on your part (to some, it's time well spent).
The terms

Ramp control: For the big airports, those frequencies are typically not staffed by FAA controllers, but airport/airline employees handling a section of the airport ground where the planes park and push back.$^1$ Also see: How do terms apron, ramp, tarmac, taxiway, parking area, gate, hardstand relate to each other?

Ground: For the big airports, there may be more than one, say one for the northern part of the airport, and one for the southern. Figuring out which runways are used when (time of day; winds) will make it a bit easier. Ground handles ground movement, anything that is not ramp or runways.

Tower: Same as ground, there may be more than one, and this one is for runways (taking off and landing).

Departure: This varies wildly, even for a single airport, it will change depending on the winds, time of day, and traffic load. It may even be combined with arrival/approach. This is the airspace around the airport outside the tower's jurisdiction, which connects to the en-route/center controllers.

Figuring it out

Find out from which gate/terminal you'll board.

Start listening to all channels days ahead and try to find your flight. You can search for archives of recordings too (there is no need to free up your schedule).

Take notes of the other flights as well, and where they park. Some flight tracking websites show the planes that are parked on the ground (playback/archive functions exist on some as well).

Use the 4-letter ICAO airport code, in this case KSFO, to search for free parking charts. Plenty of flight simulation groups release custom made versions of those charts, but of course they are of no value for real flying. Note: FAA charts are public domain, but as far as I know the ones with the parking stands are not published.

Get the rest of the charts, and combined with the above, start learning how the airport operates.

Easy way 1
If your flight will receive its flight clearance by voice radio (computerized/data clearances are taking over) on the delivery frequency, just listen closely and start switching frequencies to match those given to the pilots (e.g., United xxxx, contact tower on xxx.xxx). If not, once you catch your flight on a frequency, start frequency-hopping with them.
Easy way 2
If United still offers "Channel 9", just cheat: How was I able to just plug in my headphones and listen to ATC and pilot chatter?

$^1$ https://www.nap.edu/read/24668/chapter/15


Can the need for an engine overhaul affect the ETOPS rating?

Every time an engine is shut down in flight, it is tracked.

Engine reliability does affect ETOPS certification. In addition to the aircraft being certified, each airline is also ETOPS certified. An aircraft or an airline with a poor record could have its ETOPS certification downgraded, or even potentially revoked.

Wikipedia ETOPS Approval

  ETOPS approval is a two-step process. First, the airframe and engine combination must satisfy the basic ETOPS requirements during its type certification. This is called "ETOPS type approval". Such tests may include shutting down an engine and flying the remaining engine during the complete diversion time. Often such tests are performed in the middle of the ocean. It must be demonstrated that, during the diversion flight, the flight crew is not unduly burdened by extra workload due to the lost engine and that the probability of the remaining engine failing is extremely remote. For example, if an aircraft is rated for ETOPS-180, it means that it should be able to fly with full load and just one engine for 3 hours.

  Second, an operator who conducts ETOPS flights must satisfy their own
  country's aviation regulators about their ability to conduct ETOPS
  flights. This is called "ETOPS operational certification" and involves
  compliance with additional special engineering and flight crew
  procedures in addition to the normal engineering and flight
  procedures. Pilots and engineering staff must be qualified and trained
  for ETOPS. An airline with extensive experience operating long
  distance flights may be awarded ETOPS operational approval
  immediately, others may need to demonstrate ability through a series
  of ETOPS proving flights.

  Regulators closely watch the ETOPS performance of both type
  certificate holders and their affiliated airlines. Any technical
  incidents during an ETOPS flight must be recorded. From the data
  collected, the reliability of the particular airframe-engine
  combination is measured and statistics published. The figures must be
  within limits of type certifications. Of course, the figures required
  for ETOPS-180 will always be more stringent than ETOPS-120.
  Unsatisfactory figures would lead to a downgrade, or worse, suspension
  of ETOPS capabilities either for the type certificate holder or the
  airline.


What makes fast decompression so dangerous for the fuselage?

Often it's the structural failure that results in decompression.

The comet (the aircraft in your example) was vulnerable to fatigue cracking that would propagate throughout the fuselage and compromise the structural integrity. Nowadays the fuselage is designed to stop such cracks from reaching further than the next spar and planes are retired when the number of cycles has reached the design limit.

There are factors to take into account when the vessel decompresses. If portions of the vessel are closed off from each other, then the pressure difference between those sections can exceed the tolerance of the divider and cause damage. This caused the floor to collapse when the cargo door blew off in Turkish Airlines Flight 981.


What is the blue range indicating on this manifold pressure gauge?

It's a manifold pressure limit with altitude.  It relates to a limitation on the differential between ambient and total manifold pressure at different altitudes with turbocharged or supercharged engines; a limit on the amount of actual boost with altitude in other words, not the total pressure.

At 30000 ft, standard atmospheric pressure is only just under 9 inches.  20 inches on the gauge is 11 inches of boost above atmospheric.

At 20000 ft, atmospheric pressure is just under 14 inches, and you're limited to 35 inches, which is about 21 inches of boost.

Between 16000 ft and sea level, with atmospheric pressure between roughly 16 and 30 inches, the limitation is the red line of 40, which is anywhere from 10 to 24 inches of boost above atmospheric.

The increasing limitation in maximum boost with altitude is usually related to the reduced cylinder cooling ability of the thinning air with altitude, and the potential for detonation.


While Accuracy and Precision are closely related, they're not the same thing.
In the context of your question both are important:

Accuracy

In the US altimeters are broadly required to comply with FAR 43 Appendix E limits for accuracy (technically this is regulatory for IFR flight, but TSO'd "sensitive altimeters" will generally meet these requirements - at least when they left the factory - and that's what you're going to find in most aircraft).

The accuracy requirements provided in FAR 43 are based on mechanical altimeters, and are subject to a number of requirements (friction error limits, hysterisis limits, etc.), but the test tables there are a good guide to the accuracy of "typical" altimeters.

Also note that the accuracy of sensitive altimeters depends on the pressure setting the pilot enters (an incorrect pressure setting could mean substantial error). In "the flight levels" everyone uses the same standard altimeter setting (29.92 inches of mercury / 1013 millibars) to avoid this issue (similarly the ATC transponder transmits an altitude assuming a pressure of 29.92 inches of mercury - ATC's computers correct that value based on local altimeter settings as required).

  Depending on the design digital altimeters may also be immune to some of the accuracy-affecting issues in an analog/mechanical altimeter - for example a solid-state digital altimeter should not suffer from "friction error" as there's no rotating/moving shaft involved.

Precision

Analog altimeters are "reasonably precise" -- take this example:

The tick marks are every 20 feet. One could easily eyeball 20 foot increments, and even 10 foot increments (with the pointer directly between two ticks). Similarly the pressure settings are marked every 0.02 inches of mercury (or 1mb), allowing for a fairly precise setting of the value.

Digital altimeters are extremely precise (often offering one-foot precision in their display, and 0.01 inches of mercury for the pressure setting).

  I believe the precision requirements for altimeter markings are specified in the relevant TSOs, but I don't have those documents handy.

In both cases the precision of the markings can exceed the accuracy of the device: At 10,000 feet the FARs allow an 80 foot tolerance, and whether your measurement is presented as a needle position (roughly to the nearest 10 feet) or a number (to the nearest foot) you could still be 79 feet higher or lower than you "think" you are and be "within tolerance".

So, combining all of this together - If we have two aircraft flying along indicating the same altitude (say 10,000 feet) and both altimeters are perfect there will be zero feet of vertical separation between them (the static ports of each aircraft will be at the exact same altitude).
On the other hand if both aircraft are at the outer edge of tolerance (one +80ft, one -80ft) there will be 160 feet of vertical separation between them (discounting visual "slop" in the analog altimeter and assuming the pointer is perfectly on the line and the pressure setting is perfectly dialed in).

(In either case the answer would be "WAY TOO CLOSE!")


What happened to Widereøe flight WF0597?

Your screenshot shows the path for flight WF9480. Flightradar24 shows 2 occurrences of such flight one on the 5th August and one on the 6th August, both are training flights for landing practice. From your screenshot, you were looking at the 6th August flight.

All occurrences of WF597 show an aircraft regularly departing Bergen and landing in Kristiansand. All have been operated by a Dash-8, none by an Embraer.

You have probably mixed up two aircraft that were close in the air.


What were the historical safety statistics of airplanes?

Accidents "per flight" is unfair when comparing a 10-passenger Ford Trimotor
to an 853-passenger A380.  Passenger miles is fairer.
Even fairer is accidents per passenger, ignoring miles,
because takeoff and landing have always been more accident prone than cruise.
But even easier to measure historically is fatalities per passenger.
Commercial airline travel as we recognize it started in 1926.
http://www.planecrashinfo.com/1926/1926.htm
reports 36 fatalities worldwide that year.
1926 had about 6000 passengers in the USA.
Luft Hansa probably had more. Let's generously guess 20000 worldwide.
So the fatality ratio was about one in 550.
In 1930, 385,000 passengers were "carried on domestic and foreign airlines under the American flag".  In 1935, nearly, 1,000,000 (Berkeley Daily Gazette).  PlaneCrashInfo in these years veers away from airliners, though, and I couldn't find reliable global crash or fatality info for those years.
During World War II, and immediately preceding and following it, statistics about nonmilitary air travel are bound to be noisy.
From 1950 to 1970, per-year fatalities went from about 1,000 to 1,500
(with a dip in 1955).
Over that same interval, per-year passengers went from roughly 50,000,000 to 500,000,000.
So fatalities per passenger dropped from 1950 one in 50,000
to 1970 one in 333,000.
That second figure is corroborated by another source:
The "fatality risk per boarding" in 1968-77 was one in 350,000.
In 1978-87, one in 750,000.
In 1988-97, one in 1,300,000.
In 1998-2007, one in 2,700,000.
In 2008-2017, one in 7,900,000.
-- A. Barnett, "Aviation Safety: A Whole New World," Transportation Science 54(1), 2020.
https://doi.org/10.1287/trsc.2019.0937 paywalled;
summarized at http://www.sciencedaily.com/releases/2020/01/200124124510.htm


What level of G-force does our body experience when we are traveling in a passenger plane?

I can't find solid references, hopefully someone will come along who can.

A 30 degree bank, the most you will normally experience, exerts a force of 1.15g, or 0.15 greater than normal acceleration you feel when motionless.  The autopilot is generally designed to begin descents and climbs with no more than 0.25g and are generally calibrated to manoeuvre in 0.25g increments.  A solid rotate or a firm landing might generate a bit more.

It's reasonable to work on a range of around 0.75 to 1.25gs. Anything more than that would be uncomfortable for many people.  You should only experience g outside that sort of range in heavy or severe turbulence.


Am I required to obtain a student license before a sport, recreational, or private one?

A student pilot certificate is just a medical certificate printed on yellow paper instead of white paper and with endorsement templates for soloing printed on the back.  Other than that presentation difference it is no different than the medical exam a certificated pilot takes for whatever class medical you apply for.  The fee for this varies by examiner and may set you back $75 or so, but that (and being able to pass a medical) is the only barrier to entry.  There is no flight training or knowledge requirement to get this certificate.

Once you have a student pilot certificate / medical you have one of the requirements to solo and can train directly for any of the sport, recreational or private pilot certificates.  You'll want to focus on sport or private training, as pretty much no one pursues recreational certificates.


Although this is a question based on opinion, it might perhaps have some value as a community wiki so I've marked this 'answer' as such. I also borrowed one of Manfred's links. Feel free to append stuff to the list.

In terms of free download, I can definitely recommend the FAA Airplane Flying Handbook which can be found on the FAA web site. There are also a number of other handbooks there which are great reads. To be honest, I find this the best introductory book I know, free or otherwise.
If you're out for a good reference book, something like Anderson's Introduction to Flight will be good, but bear in mind this is hardly an easy read but does cover virtually everything you will need to know. An older edition seems to be available online.


Why do many large turbofans have a gap (of turbine blades) between the LP turbine and HP turbine?

(Source) Cutaway for the GE9X.

The gap you see is not empty. Marked above is one of the nozzle guide vanes (they have removed most of them for illustration purposes). Those vanes are analogous to the compressor stator stages.*

Labels 91 and 99 below are those vanes—sadly the stators and vanes are almost always omitted from 'drawings', yet they are as important.

(Source) Turbine stages of the RR Trent 500.

The reason why the diameter difference is steeper in the GE compared to the RR, is because the RR Trent 500 is a 3-spool engine.

In short, the vanes in both engines when omitted from drawings, give the illusion of there being a gap (wasted space).

* Nozzle guide vanes have nothing to do with the propelling nozzle at the rear. In turbine lingo, nozzle means the stator stage for the turbine.

On the funny side, here's a thumbnail from RR's own YouTube channel, absolutely bonkers exhaust. Don't trust illustrations.


How can I convert a non-ICAO (Taiwanese) pilot's license to FAA or EASA?

I can't tell you anything about the EASA regulations, but there seems to be no way to convert a non-ICAO license directly to an FAA one. 14 CFR 61.75 says (my emphasis):

  (a) General. A person who holds a foreign pilot license at the private pilot level or higher that was issued by a contracting
  State to the Convention on International Civil Aviation may apply
  for and be issued a U.S. private pilot certificate with the
  appropriate ratings if the foreign pilot license meets the
  requirements of this section.

As you said, Taiwan is not a signatory to that convention, so the FAA can't issue a license under 61.75. (61.153 allows converting a foreign ATP license to an FAA one, but it also requires that the license come from a contracting state.) I couldn't find any special regulations or exemptions for Taiwan on the FAA's site.

You said that you know people who have "converted" a Taiwanese PPL to an FAA PPL, but do you know exactly what they did? My guess is that they applied for a regular FAA license, and used their flying time in Taiwan to count towards it.


Which aircraft feature stock exterior cameras?

I fly the A320 and 321 which, at our company, had been equipped with nose cameras. The pictures, though, where just used for passenger entertainment during takeoff and landing and keep being disconnected by maintenance when failed due to high spare parts costs.


The FAA offers a nice handbook on wing skin covering for fabric aircraft you can find here. They list, clips, screws, rivets and lace as the joining methods

(source)

  Rib Lacing Cord

  Rib lacing cord is used to lace the fabric to the wing
  ribs. It must be strong and applied as directed to safely transfer
  in-flight loads from the fabric to the ribs. Rib lacing cord is
  available in a round or flat cross-section. The round cord is easier
  to use than the flat lacing, but if installed properly, the flat
  lacing results in a smoother finish over the ribs.

In some cases, or even in adition to other methods fabric cement may be used.

  Fabric Cement

  Modern fabric covering systems utilize special fabric
  cement to attach the fabric to the airframe. There are various types
  of cement. Figure 3-9In addition to good adhesion qualities,
  flexibility, and long life, fabric cements must be compatible


What Makes G1000 NXi Different From G1000?

The official Garmin announcement lists all new features.

The new hardware features are:

faster processors resulting in faster start-up, map rendering, etc.
more modern animations
a new design with better readability
LED back-lighting (increased display brightness, clarity and better dimming)
lower power consumption

The new software features are:

wireless connectivity (database updates, flight plan transfer and information shared with a mobile device running the Garmin Pilot or ForeFlight apps)
flight path for visual approaches (both for visualization and auto-pilot)
full map overlay on the HSI on the PFD
SurfaceWatch (similar to a RAAS)
full ADS-B compatibility

Further features listed are:

  Advanced Doppler weather radar capabilities, including ground clutter suppression and turbulence detection as options.
  COMM frequency identification displays the station ID, as well as frequency type.
  Display of sectional charts, as well as IFR low/high enroute charts on the MFD.
  NEXRAD weather radar imagery can be overlaid on the moving map and animated on the MFD, as well as the HSI map.
  Vertical Situation Display (VSD) incorporates terrain profile view on the MFD, taking into consideration the active flight plan, altitude constraints and winds aloft.
  Pilots can preview departure and arrival procedures on the MFD prior to loading and activating the procedures.
  Pilots can optionally overlay European Visual Reporting Points (VRPs) on the moving map, as VRPs are standard within the navigation database.
  Three-color terrain shading incorporates green, yellow and red contouring, which depicts the aircraft is 2,000, 1,000 and 100 feet above ground level (AGL) respectively.
  Aircraft maintenance personnel experience faster system software upgrades and streamlined equipment replacement.


How practical is laser designation against helicopters?

There are a number of laser-guided ground-to-air systems, and a number of those have been adapted to air-to-air and air-to-ground as well. The key is the speed of the missile, not so much the guidance system itself. An example is Starstreak.

Lasers are well focused, but not perfectly, and are easy enough to defocus to any required degree. For this role, making the beam large enough to cover potential movement of the target during the tracking cycle (often manual) while still having enough energy fall on the target for the tracker to seek is pretty much all you need. Modern solid-state lasers make this relatively easy. However, unless you have a seeker in the munition, as is the case in a laser-guided bomb, then the cone-shaped beam means decreasing accuracy with range.

Starstreak takes another approach. It projects a 2D array of dots in space modulated so the receivers on the darts can tell where they are in the array. When used with the shoulder launcher, the operator keeps the beam on the target optically and the darts keep themselves in the center.

When combined with the optional launcher platform, a tracking camera is added. This receives the reflected laser signal from the target and uses the same modulation to determine how closely the array is to the center of the target. It uses this to automatically track the target, and thus the missiles get the benefit of semi-automatic tracking without having to carry the seeker on their nose.


What are the physical laws for upscaling an RC model to 1:1?

This is not a full answer: much is mentioned by Michel Touw, but I'd like to correct a common misconception.

The mass growing as the third power of linear dimensions applies only to solid objects. But the airplane is not solid; rather, it's a thin-skinned frame. (Unless it's a solid foam RC model). Therefore, its mass should grow with the area, as the square of length.

However, this is, of course, not quite true. In reality, you need thicker skin, thicker spars, etc., and these elements will get heavier 'properly' with the cube of length - and even more, because they'll need to support themselves as well, with their added mass.

In the end, the mass of airplanes grows between the second and third power, and much closer to second.

Let's take B734 and B772 for example, which differ close to twice in linear size. Their empty weight (roughly 33 and 140 tons, depending on modification) differs by 4.25 times, which is approx. 22.1. MTOW has a similar ratio: 68 vs 300 tons, 22.15.


How are insects and arachnids kept out of commercial passenger airliners?

Like anywhere else, they only become a problem if they affect safety. That is why things like pitot probes and static ports are covered to prevent insects like  mud-daubers' from building their homes inside. Depending on the area it could only apply if the aircraft is not flying for x amount of time but in areas where these insects are very active it could be required for shorter transits. The recent Malaysia Airlines case (Brisbane, Aust) where the pitot-cover was not removed before flight was a case where the covers were place for a short transit because of these insect activity.

If the destination country has laws in place where the entry of non local insects is not tolerated they may require the airline to spray the holds before departure. I remember doing this for flights to Australia. We had cans with a 'lock' trigger (continues to spray without finger pressure) which we would activate and leave in the holds before closing the doors. It was important to notify the crews beforehand as the mist could activate the smoke detectors.


How to identify transmit labels for a particular equipment in ARINC429?

As Gerry mentioned in their comment, the equipment ID label (377) indicates to the receiver how to decode the labels being received on that ARINC 429 channel.
The transmitting equipment (Tire Pressure Monitoring System) would send label 377 with the value 03C at it's appropriate rate (usually every 1000 ms) and then labels 060 through 064 at their appropriate rate.
The receiving equipment gets the Equipment ID from label 377 it received and then knows to decode labels 060-064 according to the TPMS definitions.


Why aren't Russian jet airliners popular even in Russia?

It all comes down to cost. It is rather easy to build a large jet aircraft. To build an efficient and reliable large jet aircraft is not that easy. If you read the Wikipedia articles you linked carefully you find in the Il-96 article:

  [...] the Il-96-300 had been deemed inferior to counterparts from Boeing and Airbus [...]

and in the Tu-204 article it is indirectly stated that the reliability of the engines isn't that great:

  The PS-90A2 [engine] is expected [to have ...] life cycle cost saving of 35% over the original engine with a simultaneous increase in reliability in the 50 to 100% range.

Your next problem is line maintenance capabilities. That is more or less a chicken and egg problem. The Il-96 is a long range aircraft and you need maintenance on your destination. You need a certified mechanic, tools, and components. Component availability is another problem. If there is only a handful of aircrafts of one type there is no large spare supply around the world thus increasing the cost for the operator.

Another problem is that at least the Tu-204 is not fit for the current airspace structure:

  The Tu-204SM [...] is an upgraded version of the Tu-204-100/300. [... T]here are numerous upgrades, largely aimed at meeting the current and near-future Russian and international standards [...].

And it requires a three man Cockpit Crew. Remember: The Tu-204 is an A321 sized aircraft.

  The new cockpit features allow the Tu-204SM to be flown by a two-pilot crew (as compared with the three-pilot arrangement of the original Tu-204 series).

So far the improved Tu-204SM hasn't materialized so far and likely never will.

  [... There are] currently no orders for the Tu-204SM, and Tupolev has frozen on development work on the aircraft and the UAC will withdraw it from their list of aircraft prices as soon as the Irkut MC-21 comes to the market.

As an airline has to keep the costs under control it is unwise to buy an aircraft which, from the start, is inferior to its competitors. It's a simple calculation: What costs more over the predicted lifespan. Initial costs (unit price) might be lower with one product but you have higher costs for fuel and maintenance. Add in some reliability problems and you get the costs incurred by those on top. Another product might have a higher unit price but the running costs are lower. Now do the math and choose whats best for your airline.

All quotes come from the Wikipedia articles on the Ilyushin Il-96 and the Tupolev Tu-204.


How are aviation sectionals and enroute charts created?

I believe the FAA got out of the printing business by implementing a new business model for charts where they license the product to private industry who then take on the risk/reward of the printing process for their customers.

From the FAA AIS website:

  The Federal Aviation Administration (FAA), Aeronautical Information Services (AJV-5), is transitioning aeronautical charts and related products print and distribution operations from existing contract(s) to multiple no-cost agreements with private industry. Digital product files allow industry the opportunity to print, sell, and distribute aeronautical charting products to the public in an Available on Demand (AOD) approach. Any party interested in the opportunity to become an approved print provider should submit product qualification samples from the files below (in accordance with instructions in the Print Provider agreement).

More detailed information about the program is also available through the FAA contract award management site via an official announcement. So to answer your question, the printing of charts is now handled by private industry, not the FAA.

Since you mentioned Jeppesen specifically, note that they are a bit of a different concept because they take raw data from each state's official AIP and then integrate it together in their own way and perform other value-added services. They then print their own end-product for their customers.  It is based on the same raw data but their product should not be considered the same as what is produced by the FAA.


What are the conditions for the percentage power vs fuel consumption figures in the engine operator manual?

The correct source for burn data is not the Lycoming operator manual, but the aircraft manufacturer's manual.

All modern POH have the consumption data qualified (in tables) relative to altitude and temperature.

When adding a new plane to our fleet, we enter that data in and do a linear regression on the data, so that we have a generalized equation for flight planning purposes.

You need to look at the aircraft documentation, not the engine documentation, because the same engine in different planes will have different performance. The POH will have figures which were established empirically, by the manufacturer's test pilots. Fuel burn tests are conducted at various altitudes, and temperatures.

Please note that to answer your fuel burn questions, it is essential to know the aircraft, configuration, and really, have that specific POH.  Then the questions you pose are readily answered.


Is it possible to disengage only one axis of a two-axis autopilot?

Some autopilots found on advanced aircraft can be engaged on selected axis only, for example Boeing 737, 747-200 & MD-11. There are three autopilot indicators on the Boeing autopilots: auto throttle, roll and pitch. Each can be in a different mode.

Here a Boeing 737's autopilot roll mode is set to Heading Select (HDG SEL) while the Pitch is flown manually (CWS P):

The pilot can pull or push the yoke, and the autopilot will roll the aircraft automatically. If the pilot steer the yoke left or right, the roll mode will change to CWS R.

In this image below, the pilot is manually Rolling the aircraft (CWS R), but the autopilot pitch mode is set to Vertical Speed mode.

Later models, such as the Boeing 777, does not have this feature - both pitch and roll modes must be engaged together.


How close can separation be during a landing clearance?

According to the avherald article, the airport was operating below visual minima, thus no visual approach would have been possible. Unfortuntely, the ATC communication transcript is not available, so we will will not know whether the CAT III AutoLand approach by the B773 was communicated to ATC, which would not allow the Avro to enter the runway protected area during the B773's approach or whether this was a decision by the B773 crew only.

Since the airport was operating under CAT I procedures, the B773 is likely to have been cleared for a CAT I ILS approach. The Avro will have been cleared for departure before the B773 was cleared to land, ATC has most likely used a non-withheld landing clearance.

  321.5 Landing clearance need not be withheld until prescribed separation exists if there is reasonable assurance that the appropriate separation will exist when the aircraft crosses the runway threshold. However, do not clear an aircraft to land before a preceding landing aircraft has crossed the runway threshold.

The runway is considered no longer occupied if the preceding departing aircraft has reached Vr and has rotated, although still being over the runway. If ATC can be reasonably sure that this will be the case when the landing aircraft crosses the threshold, the landing clearance can be issued.

The BFU bulletin reads:

  The B777 crossed the runway threshold of 08R at 12:09:09 in 40ft. Six seconds later, the BAe Avro crossed the opposite runway threshold at approx. 380ft.

(Source: BFU Bulletin NOV 2011 - Translation: Own Work)

Is it typical for aircraft to be so close during approach and departure? Yes, aircraft can be close during these phases, depending on procedures in use and meteorological conditions. Aircraft can be asked to maintain visual separation to preceding traffic in VMC, however without the full transcript of the ATC communication, this will not be answerable in regards to your scenario in Munich.