How do airlines handle their non-standard passengers for the load control process?

Airlines are responsible for weight and balance control programs. In the US, FAA AC120-27 describes how these work, and it specifically describes the treatment of special passenger groups like sports teams:

What are the standard average weights for special passenger groups that do not fit an operator's standard average weight profile?

a. Sports Teams.
(1) Actual passenger weights should be used for nonstandard weight groups (sports teams, etc.) unless average weights have been established for such groups by conducting a survey in accordance with the procedures established in Section 3 of this chapter. When such groups form only a part of the total passenger load, actual weights, or established average weights for the nonstandard group, may be used for such exception groups and average weights used for the balance of the passenger load. In such instances, a notation should be made in the load manifest indicating the number of persons in the special group and identifying the group; e.g., football squad, etc.
(2) Roster weights may be used for determining the actual passenger weight.
(3) A standard allowance of 16 pounds per person may be used to account for carry-on and personal items as provided in the operator's approved carry-on bag program.
(4) If the carry-on bags are representative of the operator's profile but do not meet the number of bags authorized per person, the operator may count bags and use a 16 pounds per bag allocation.
(5) Actual weights must be used in cases where the carry-on bags are not representative of the operator's profile.
b. Groups that are predominantly male or female should use the standard average weights for males or females provided in Table 3-1.
c. Military Groups. The Department of Defense (DOD) requires actual passenger and cargo weights be used in computing the aircraft weight and balance for all DOD charter missions. This requirement is specified in DOD Commercial Air Carrier Quality and Safety requirements (reference 32 CFR part 861, section 861.4(e)(3)(ix), as revised). FAA-approved air carrier weight and balance control programs may be used to account for carry-on/personal items for mixed loads of military and their dependents (such as channel missions). For combat-equipped troop charters, the Air Mobility Command (AMC) will provide guidance to account for the additional weight. If aircraft operators perceive that the weights provided are understated, they should seek confirmation of the actual weights and should make reasonable upward estimations and adjustments to those passenger and/or bag weights.

In other words, use actual weights or come up with an appropriate method to determine appropriate average weights for special groups.


Are there any problems opening a helipad close to an airport?

In the US, normally it is not a problem.  I would talk with the tower supervisor, to see if a planner could be consulted before you go too far down the road and start paving or something like that.

A good place to start would be a memorandum of understanding, where you and the FAA would work out the operations out of the field, and discuss arrival and departure coordination.

I could come up with a list of twenty heliports within 1.5 miles of Class C or D airports. Funny how hospitals end up near airports. Ditto for police facilities.

Life is easier if you do not plan on trying to get instrument approaches.


Why do we no longer have a navigation officer on modern commercial flights?

Navigation has gotten much simpler over the years.  Initially, navigation would be done by a combination of dead reckoning, looking out the window for landmarks, and for night or long-distance flights, by celestial navigation (many old airplanes have a window at the navigator's station specifically to let the navigator see the stars).  This took quite a bit of time and effort, so the pilot couldn't do it and also fly the airplane.

In the 1920s, radio navigation was added to the navigator's toolkit, but finding bearings to beacons and calculating a location was still an entirely manual process.  Additionally, radio beacons didn't cover the entire world, so older navigation techniques were still needed for most flights.

In the 1950s, fully-automatic radio direction finding systems became common and navigation beacons were available across most of Europe and North America.  At this point, the workload involved in navigation dropped to the point that the pilot could also navigate: plot out the sequence of NDBs to follow ahead of time, then tune the radio and follow the navigation display.

Very recently, navigation has been integrated with the autopilot to the point that the pilot can punch in a sequence of waypoints and have the airplane fly the route entirely on its own.

And yes, even today if the electronic navigation system fails, the fallback is map, compass, and slide rule.


Advantages to doing an initial instrument rating training in a Cirrus over a conventional aircraft?

There aren't any. Unless you are planning on purchasing a Cirrus, you'd just be burning money for no good reason by training in that. An instrument rating is an instrument rating regardless on what aircraft you train. What is important is the quality of the training, ground and flight. If you think about it, I am quite sure you can find better ways of spending the money you will save.


Why do NY ARTCC Standard Operation Procedures have different altitude limits than the NY Class B airspace?

The commenters have a good point that the SOP documents you liked are for hobbyist simulation and are not necessarily faithful reproductions of real-world procedures. But even in the real world who owns which specific volume of the air at which specific altitudes is not necessarily correlated with the regulatory airspace class for a given volume of air at a given altitude.
The two altitude limits are different (not "incompatible"!):

One is regulatory, and binding on pilots. No pilot may operate in the Class B airspace, unless they have received a clearance from ATC allowing them to do so. For IFR aircraft, they will receive their clearance on the ground; they will be cleared to fly a certain route at a certain altitude, and it does not matter what airspace class the route crosses or enters, because they have already received a clearance to fly that route. For VFR pilots, they may operate as they wish in Class E airspace, but before entering Class B airspace must receive a clearance from ATC telling them which heading to fly at what altitude. (There are similar but less restrictive requirements that VFR aircraft must abide by to enter Class C or Class D airspace.)
The other is not regulatory, and has to do with ATC. Regardless of the airspace classification of any volume of air, one and only one specific control position is responsible for all aircraft operating within that volume. The document you found lays out the boundaries (in 3D space) for those volumes of air, which are not directly relevant or known to pilots. The volumes will be designed so that certain activities (arrivals joining the localizer and coming in to land, or departures climbing away from the airport) can be monitored and controlled by only one controller without unnecessary handoffs.


What is the problem if the temperature of the oil and heads of cylinders is too high?

Piston engines are designed to run within specific temperature ranges. Going above this range might effect the lubrication [hot oil may not provide the right amount of protection to moving parts, If hot enough it could melt seals, or even catch fire.]
the other danger is as metal changes temperature its structural property's change. If a metal gets too hot it becomes softer and may become less resistance to forces. also there is the issue of shock cooling, if a hot engine gets cooled to quickly, it may unevenly cool, and due to the difference in heat expansion could crack or fail.


Where can I find data on the number of single propeller aircraft currently in operation in the EU and US?

You can download the entire FAA aircraft registration database and analyze it however you want.

I have no idea about EASA, but because aircraft registration is delegated to member states you'll probably have to look at each one individually (e.g. the UK). I don't know if all EASA countries consider aircraft registration information to be public or not.

You could also look for a commercial data provider that sells the data you need, of course.


What forces act on cascade-type thrust reverser blocker doors?

ATTENTION, very coarse analysis !

This is a bit vague, but maybe this will give you a starting point.

Generally on turbofans, about 70% of the total thrust is provided by the fan.
If you consider a high power brake using 80% of the max thrust, this gives you
TADAAAAA 25000*0.8*0.7 = 14000 lbs (yup that's rocket science).

Now, this gives an approximation of the power provided by the fan. However, the outlet angle is not parallel to the main flow. Assuming that the mass flow rate as well as the magnitudes of the velocities are conserved in the transfer and that the outlet angle is about 45° from the engine axis, it gives

qm x (v2-v1) = F where qm is the mass flow rate, v2 the outlet velocity vector and v1 the inlet velocity vector, while F is the force of the fluid on the structure.

Because of the angles this gives qm x (0.5+1) x v1 = FX and qm x 0.5 x v = FY on the doors.

Then, assuming (yes, I said to pay attention at the beginning of my answer) that Ffan = qm*V1 = 14000 lbs, which is quite doubtful unfortunately, we obtain FX = 21000 lbs and FY = 7000 lbs.

Regarding stresses, it is IMHO far to dependent on the actual parts of the engine to assess.

If anyone can check this to be sure, be my guest ;).


How do commercial flights get overbooked?

Airlines have lots of historical data for any given flight segment that they can use to give statistical probabilities of people missing flights due to various factors such as misconnection or just not showing up.  An airline is a profit driven corporation and to maximize revenue they want full airplanes.

If they know for a flight that 5% +/- 2% of passengers fail to board they can pretty safely sell around 103% of the seats to maximize passengers and minimize risk of overboarding.  Statistics are averages, however, and if you sell 103% of your capacity it is entirely possible for a given instance of that flight to be overbooked.

In most cases of overbooking, volunteers can be found that will give up seats if the plane becomes full.  US airlines generally top out at around $800 compensation for volunteers, so if you are willing to do so it can be advantageous to wait for them to get desperate for volunteers.  If no volunteers can be found it is possible to be involuntarily bumped off the flight and you should consult with the specific airline for any rights you may have in that case.


How do GLS avionics plot an entire accurate approach path?

The best reference is the ICAO GBAS Guide.  Unfortunately, it doesn't have diagrams to help understand it.

The Final Approach Segment (FAS) is a geodesic path to the runway. It is horizontally aligned with the runway center line and has a glide path angle that descends to the Threshold Crossing Height (TCH) directly above the Landing Threshold Point (LTP). This can be seen in the following figure:

Source: SlideShare

All the necessary data is contained in the type 4 message as the ICAO table below shows:

Source: ICAO

There is one Type 4 message for each approach supported by the GBAS ground station.

The LTP/FTP latitude, longitude, and height are coded in the data block. The FPAP is coded as a delta Lat/Lon from the LTP/FTP. Horizontally, the FAS will pass through both of these points and thus be aligned with the runway center line.

The vertical component is defined by the Threshold Crossing Point (TCP which is the LTP vertically raised by the TCH) and the Glide Path Angle (GPA).


Could an EFB-based pre-flight check be automated?

An EFB could not be used for this purpose, all your suggestion would do is replicate things that are already done by EICAS (engine indication and crew alert system).  The reason for this is that "receiving", "pre-flight" and "before takeoff" checklists all involve physically moving switches.  The EFB would be unable to perform these actions (e.g. an EFB cannot select flaps 9 degrees).

What an EFB could do, if tied into the aircraft ARINC data bus, is to verify things.  Such an EFB could verify that flaps are indicating a set position and could alert us if it were not.  However, as mentioned, the EICAS already does this, and if I were to advance a thrust lever beyond taxi power I would get a master warning and a takeoff configuration EICAS message as well as an aural warning "TAKEOFF FLAPS" (EMB-145).

You also mention the bulk of paper carried as a reason for this, but this is not relevant to the checklists.  The checklist on many large airplanes is a single sheet of paper, laminated and installed in the airplane.  Some airplanes may have a few sheets, but overall checklists account for very little paperwork and they belong to the airplane, not the pilots.

Where EFBs do help with paperwork are the approach charts, which account for 75% of what I carried on any given flight.  Three 2" binders, full of nothing but approach plates.  An EFB can condense that down to a tablet, and this is where the value of the EFB is.


Do pilots need to know how to use a sextant?

Ooh, a celestial navigation question...about airplanes... I never thought I'd see one of these in the 21st century!

To answer the basic question: Pilot training doesn't cover sextant use, but there is still a "Flight Navigator" certificate (you'll find it in Part 63 of the FARs), and an associated Flight Navigator Handbook (FAA-H-8083-18), last updated in 2011. The written test question bank is also available if you want an idea of what the FAA expects you to know in order to earn that certificate.

  Can a sextant be used while flying?

Yes, if you have a clear view of the sky overhead.
Aircraft used to be designed with "sextant ports" as shown in Stelios' answer, and special aircraft sextants (indirect-sighting, with a bubble to provide a horizon, and usually some kind of averaging mechanism and timer).

  How accurate/reliable is a sextant, both standing still and at 500+ mph?

A sextant is a pretty accurate tool under the right conditions, if you know how to use it.
Stationary on the ground you can do a surprisingly good job with a sextant, see for example the US/Canada border monuments. I'm out of practice, but on calm water I used to be able to fix my position to within about 1 minute of arc (1 nautical mile) on any given line.
To put that in perspective, that's slightly better navigational performance than a VOR provides at distance (2-4 nautical miles), but substantially worse performance than GPS (within a few feet).

As far as reliability, the reliability of a ship's sextant is pretty good: much like a mechanical E6B flight computer it'll work fine unless you abuse it (drop, step on, etc.).
Reliability of an aircraft sextant (or any other bubble sextant with an averaging timer) is not quite as good because there are more moving parts involved, but properly maintained they could be trusted to work when you needed them (and most failures could be compensated for by a decent navigator).

The problems with sextants that make them impractical for modern air travel are:

Speed
Sextants don't tell you where you are, they tell you where you were when you made the observation. The averaging mechanisms I mentioned earlier allow aircraft sextant to partially account for the fact that the aircraft was moving (both vertically and horizontally), but at modern speeds you cover a minute of arc pretty quickly. Radio navigation systems and GPS provide much faster position updates than you could get with a sextant.
Complexity of the instrument
Aircraft sextants are precision instruments. They need to be maintained and calibrated or they won't be accurate when you need them, and as I mentioned there are a lot more moving parts to an aircraft bubble sextant than a basic ship's sextant.
Complexity of the process
Using a sextant also require an operator (navigator) who knows what they're doing in order to take the sighting and compute the position, compared to radio navigation (VORs, VOR/DME, or GPS).
Most pilots don't have any training in using a sextant (my experience comes from sailing), so having one would be useless to them.
Weather
While the sextant is a reliable instrument the stars are not reliable: They're always there, but sometimes they're not visible. You can't see most of the stars & constellations you would take a sighting of during the day (usually only one star is visible), and clouds can obscure them when you want to take a sighting, delaying or preventing your position fix.

  Are sextants found in any cockpits today?

Certainly not in any light GA cockpit I can think of, and probably not in any single-crewmember cockpit: Even if you held both a pilot certificate and a flight navigator certificate a pilot with their head buried in the sextant is rather useless for actually flying the plane.

I would assume that most commercial cockpits also no longer have a sextant as modern jets don't include a sextant port, so there's no way to take a sighting.

There might be a few restored vintage aircraft that have a working sextant onboard, but I doubt those are used for practical navigation (they're probably not used at all, except possibly to demonstrate how it was done).


How does a (non-pilot) arrange a tour of an ATC facility?

For tours, call the facility and say you're interested in aviation, and would like a tour, same as pilots. Depending on the facility, business hour tours are preferred, though others will let you come any time they have available staffing to escort you around.

As far as I know, there are no video feed of any ATC facilities.


What causes the nose landing gear knocking noise on a Boeing 777 while taxiing?

(source)

That's a pilot taxiing perfectly on the centerline, which makes one of the two nose landing gear tires hit all the taxiway centerline lights.

Just like the sound the tires of a car make when they hit the cat's eyes on a road at speed.


Do promotional flight routes have a historical precedent?

It's not the first time they do it. Back in 2012 they wrote 787 and the Boeing logo:

Planes have been drawn before by others as well.


Can training for an Instrument Rating be applied towards a commercial pilot certificate?

Short answer: yes, if the training has been logged with the remark that it meets the requirements of both 61.129 and 61.65.

This topic became confusing because of an FAA interpretation that says:

  [...] are the requirements of 14 C.F.R. §61.129(c)(3)(i)
  [commercial certificate] met by the student getting an instrument
  rating or training for an instrument rating? The answer is no. The
  training giving to satisfy the instrument training aeronautical
  experience of §61.129(c)(3)(i) may also be used to count towards the
  aeronautical experience of §61.65(e) [instrument rating], but the
  opposite is not true. The reason for this is that the training
  required under §61.65(e) is general, while the training under
  §61.129(c)(3)(i) lists very specific operations that must be
  accomplished to satisfy the requirements.

But that interpretation was surprising to many people because it implied that a commercial certificate requires additional instrument training, even if you already hold an instrument rating. So AOPA requested a clarification (more information here); you can read the whole thing, but the key statement from the FAA is this:

  We are merely clarifying the requirement that the applicant for a
  commercial pilot certificate provide evidence that they have met the
  requirements of §61.129. There is not an exact equivalence between the
  training required for an instrument rating under §61.65 and the
  aeronautical experience requirements under §61.129.

Practically speaking (as the AOPA article explains) that means that your CFII should explicitly log the training as covering both requirements:

  [AOPA] urges instrument pilot applicants and flight instructors to be sure
  that instrument training is clearly logged to indicate that the
  training given meets the requirements of 14 CFR 61.65 as well as those
  of 14 CFR 61.129. That would avoid questions about the training’s
  applicability should the pilot one day advance to training for a
  commercial pilot certificate.


Can a "crash landing" be used for FAR 61.57 currency?

As far as I can find, the FAA doesn't define the term landing so it could be argued either way.  The "typical" definition of landing is:

  1: an act or process of one that lands; especially :  a going or bringing
  to a surface (as land or shore) after a voyage or flight

That definition doesn't say that it has to be "controlled" or that the airplane has to be usable again!  Even if you decide that it wasn't a "successful landing", you could always get your third landing later if you are still allowed to fly, and then carry the passengers.

So this brings us to the second part of your question:  Are you allowed to fly after an accident?

Since you had an accident (as defined by 49 CFR 830) you must immediately notify the NTSB of the accident.  Once you do that, you have 10 days to file the required report.

At this point, you still have a valid pilot license and can legally fly another airplane.

Chances are however, that you will be receiving a certified letter from the local FSDO requiring a reexamination in order to keep your license because your competence has been called into question.  If you don't call them to make an appointment, they will start the process to suspend your certificate.  During this time, you can also continue to fly because you still have a valid license.

The FAA can also use their emergency authority to immediately suspend your license if they feel that it is warranted.  This can be appealed to the NTSB board if you feel that it isn't justified, and they have up to five days to respond.  At this point you are not allowed to fly pending the response from the board.

This, and a lot more information can be found on AOPA's FAA Enforcement Webpage.


Why couldn't Air Moorea Flight 1121 use pitch trim to land safely?

All quotes in this answer are from the English translation of the BEA accident report.

The elevator cable broke at "an altitude estimated at between three and four hundred feet",(p. 7) and there were eleven seconds between that time and the point of impact. If it had happened higher, the pilot would potentially have had time to figure out what happened and pull out of the dive with trim. Taken by surprise and not knowing what happened, the pilot simply did not have time to recover.

The Twin Otter would have been demonstrated to be recoverable from an elevator cable break as part of its certification (p. 17):

  The CAR 3 regulation, basis of certification for the DHC6, requires a flight test demonstrating the aeroplane’s capacity to land using only the elevator trim in the case of failure of the primary longitudinal control of the aeroplane.

However, there's a big difference between "can be landed using just trim" and "can be recovered by a pilot who is surprised by the emergency". Flight tests performed during the investigation showed (p. 63, emphasis mine):

  At [the height the incident aircraft was at], only immediate action on the trim located on the centre pedestal would make it possible to recover the airplane. The test also showed that from level flight it takes about three seconds for a pilot trained for and prepared for this exercise to recover the airplane.

Unfortunately, on this flight there simply was not enough time to discover the problem, figure out what went wrong, and recover (p. 63):

  The highly dynamic nature of the events following the failure must be emphasized here. Eleven seconds passed between the pilot’s exclamation and the impact. This only left a short time for the pilot to analyse the situation and apply a solution that he had to improvise. In addition, the stress associated with the airplane’s attitude and the difficulty in estimating his height, in the conditions on the day, in relation to the surface of the water, certainly affected his powers of analysis. The pilot was not trained or prepared, either during his training or during type rating, as indeed most pilots aren’t, to react to a loss of pitch control. Only a reflex action could thus have
  allowed him to recover the airplane before the impact.

To answer the edits to the question, note that the airplane was not trimmed to "fall out of the sky". The pilot called out the trim checklist item before flight(p. 17), and so should have set it to the takeoff setting. Presumably this would require gentle back-pressure for rotation and climb. The event that initiated the failure process was retracting the flaps(p. 39). This changed the flight dynamics, and therefore the elevator control loads. The flight testing discovered that this created a "pitch-down moment"(p. 39):

  To counter this effect and maintain the aeroplane on its initial trajectory, it was necessary to exert considerable pitch-up effort on the elevator control.

This is not a cause for concern. The procedure is to hold pressure on the controls and adjust trim to relieve the pressure. However, it was at this point that the elevator cable snapped, so the pilot was interrupted and didn't complete the process. If the incident had happened at a higher altitude, the airplane would have recovered itself from the upset (p. 42):

  [S]tick free, the flap retraction led to a pitch-down moment varying the aeroplane
  trim between 20° and 30°, the rate-of-climb indicator going to stop at less than
  3,000 ft/min and speed reaching 140 kt in twenty seconds, then the aeroplane
  recovered on its own in level flight in five seconds, the total loss in height being
  seven hundred feet[.]

To the last question, flying inverted would not be necessary for recovery. I do not know the maneuvering characteristics of the DH-6, but I am unsure that an outside loop could successfully be completed starting at 300-400 AGL.


Are runway safety areas for both emergency landings and aborted take-offs?

Yes, the runway safety area is to provide a buffer zone for aircraft that leave the runway for whatever reason, including rejecting a take-off late or by overshooting on landing. It's not specifically for an "emergency landing": sometimes the emergency might only arise during the course of the landing, for example tyres bursting or pilot error.

If it were only for emergency landings, then parallel runways probably wouldn't need to all have a RSA, because the distress aircraft could be offered the one runway that has one. But in fact every runway needs an RSA, because any landing might suffer a runway excursion.


The Seaplane Pilot's Association publishes a Water Landing Directory that includes seaplane facilities and flight planning maps for cross countries. This lists facilities that offer seaplane rental's. There is a discounted price on the directory for SPA members.


What is the fluid released from the tail of this clipped Turkish airliner?

It is hydraulic fluid. This works on 3000psi so that would explain the geyser.

I am not familiar with the A320 family but on most aircraft hydraulic system there are usually isolation valves to ensure that part of the system remains serviceable if there is a sudden loss of pressure/fluid in one part of the system.


Does it make sense to use a canard in combination with a conventional aft elevator control surface?

Actually, for most tasks it would be most helpful to add the horizontal tail and to remove the canard. There have been only a few canard designs and even fewer three-wing designs in the past. Off-hand I remember just three:

Voisin-Farman biplane in the Musée d'l Air in Paris (picture source)
Gabriel Voisin was the founder of the first commercial aircraft factory and designed a biplane with forward elevator and aft stabilizer in 1907 for Léon Delagrange and Henry Farman. He had chosen a similar layout for his very first glider design in 1905 already, most likely because the question where the elevator goes on an airplane was a matter of hot disputes at those times.

The second one is of course the excellent Piaggio P.180 Avanti (picture source), where the highly loaded canard allows to move the wing behind the pressurized cabin and the lightly loaded elevator provides ample control authority at all flap settings and center of gravity locations.
The third one is the Sukhoi-30 MKI, which adds small, closely-coupled canard wings to the conventional layout of basic the Su-27 / MiG-29 design. Thinking of experimental Russian designs, I could also mention the MiG Ye-8, a MiG-21 with a free-flying canard surface (picture source):

If you don't expect to have a wide center of gravity range in your UAV, use fewer wings. One big one for the lift and a second one for stability and control should be all you need.


(See Included ILS Chart) What to Do After SMT RDL 084?

SMT RDL 084 is simply a lead radial, so it is there to let you know when to start your turn so that you can intercept the SIU 253 course without overshooting it during the turn.

Just below and to the left of the airport is the box which shows the ILS frequency.  It tells us that the DME identifier for this ILS is ITFR, so the distances are provided based on the distance from the DME transmitter associated with the ILS.


Are there any twin engine aircraft without counter-rotating props?

Twin enigned aircrafts without counter-rotating propellers

A great many twins don't have counter-rotating props:

One such aircraft is the BeechCraft Baron 58, as seen in this YouTube video.

Another aircraft I can think of is the King Air 350.

It is not any more or less common to have one or the other.

Contra-rotating propellers

Another interesting solution to the P-factor (prop pulling towards one direction), especially on single engine aircraft is contra-rotating props, two propellers on the same shaft that spin in opposite directions.

This is mainly for single engine racer aircraft, but there are multi-engine aircraft known to have it, such as the Soviet Tu-95 Bear bomber.

The pic shown here is a Spitfire Mk. XIV:

A better explanation of the P-factor

P-factor is the term for asymmetric propeller loading, that causes the airplane to yaw to the left when at high angles of attack.

Assuming a clockwise rotating propeller it is caused by the descending right side of the propeller (as seen from the rear) having a higher angle of attack relative to the oncoming air, and thus generating a higher air flow and thrust than the ascending blade on the left side, which at the other hand will generate less airflow and thrust. This will move the propellers aerodynamic centre to the right of the planes centreline, thus inducing an increasing yaw moment to the left with increasing angle of attack or increasing power. With increasing airspeed and decreasing angle of attack less right rudder will be required to maintain coordinated flight.


How do the vortex created by wing tips affects the lift?

The lift over a wing comes from an imbalance of pressure above and below the wing. The higher the pressure, the more force is imparted to the wing. Thus, by generating a higher pressure on the bottom of the wing then on the top, a net upward force is created which offsets the pull of gravity on the airplane. The greater the pressure differential, the more lift is created.

At the end of the wing, there's nothing to prevent the higher pressure underneath from causing air to "spill over" the end of the wing into the lower pressure area. Thus, the pressure at the end of the wing tends to equalize itself, with a corresponding decrease in lift.


What is the lifespan of a level D simulator?

As long as it's maintained, and replacement parts are available, there is no limit. Although maintenance could end up costing more than the simulator itself:

CAE says the Series 5000 will offer a 25% reduction in lifecycle costs, which tend to be two to three times the original cost of the simulator during a 20-year lifetime (...)
— flightglobal.com, 2008

The 20-year lifetime mentioned above is what would a training center expect, as that's typically how long an airliner model stays in service in sufficient numbers to promise a continued demand.
Delta Flight Museum still operates a full-motion 737-200 simulator (Delta introduced that model in 1983, almost 40 years ago).


Why is the maximum speed of current fighter aircraft lower than those from the 1960's and 1970's?

Speed was life in air combat until the jet age. The pilots who became Air Force generals in the Fifties had learned their trade in the Thirties when speed was the most-desired quality in a fighter. Naturally, the ability to be faster than any adversary was very important to them. When the requirements for new fighter aircraft were written in the Fifties, those generals made sure that a higher top speed was part of the specification.

When those supersonic-capable aircraft were used in real conflicts, something very surprising and unforeseen happened: They did hardly ever fly supersonic. When the Air Force in the late Sixties accumulated the flight data from several years of Vietnam war air combat, they found that all aircraft had accumulated just minutes at Mach 1.4 and only seconds at Mach 1.6 out of more than 100,000 combat sorties¹. Never was even Mach 1.8 flown in aircraft which had been optimized for Mach 2.4 (F-104, F-105, F-106A, F-4D/E and F-111).

To cite from this study why speed stayed mostly subsonic:

  The first of these reasons lies in the shape of the turn rate vs Mach number relationship for an aircraft. […] In combat, each pilot has the tendency to to fly his aircraft so as to maximize his turn rate. He thus gains angular position on the enemy which, in turn, may permit a missile launch or a gun firing. […] It can be seen that the pilot's urge to maximize his turn rate will unfailingly drive his Mach number to about 0.7. Thus, if the pilot is going to join in combat, […] his speed will inevitably drop to subsonic speeds. […]
  Note also, that even if the turn rate is held constant while increasing the speed, […] the turn radius and load factor increase, bringing with it increasing problems of keeping the enemy in sight.

The second reason given in the study is the dramatically smaller combat radius (the maximum distance the airplane can travel from its base, accomplish an objective and return) once the aircraft starts to fly at supersonic speeds. Even for flying into the combat arena supersonic speed was rarely advantageous. Northrop studied a multitude of intercept cases and found that speeds above Mach 1.1 were almost never helpful because they curtailed the combat radius severely.

Now you need to know that the top speed is an important driver in airframe design. Flying at Mach 2+ requires heavy and complex intakes, a heat-resistant structure, high wing sweep and heavy, low-bypass engines. This all degrades the combat qualities at high subsonic speed, which was where those aircraft were used the most. Building into them the capacity for Mach 2+ made them worse for what they were actually used for.

From the late Sixties on this lesson was incorporated into the newer designs like the F-16. Stealth again decreased the importance of supersonic capability, and the maximum sustained speed of the F-22 was actually reduced from Mach 1.8 to Mach 1.6 to reduce the heat load on the composite wing leading edge.

¹ Source: Northrop F-5 case study in aircraft design, AIAA Professional Study Series


Would a de-aerating fuel tank have any benefits?

There are ways of preventing air from being pulled into fuel lines due to change in speed,
direction, or orientation.  On of the simplest is called a "clunk" line, which is a flexible hose with a weighted fuel inlet at the end. The inlet and fuel simply fall to the "lowest" level G forces take it.

As far as fuel entraining air by agitation, important factors are viscosity and the chemical
make up of the fuel.  Fuel is generally "thinner" than oil so air can escape more easily.
Chemically, fuel does not have the tendency to form bubbles as a mixture of soap and water would.  Air entrainment simply is not an issue with flight maneuvers.  No doubt the oil
companies have a good number of chemists to keep it that way.


What are the costs of 1 hour flight in modern low-cost airlines?

For the low-cost model there's an article called The true cost of flying revealed, which uses a 154-passenger A320 for its figures.

  According to the calculations, each passenger on board an Airbus A320, which has a capacity of 154, costs the airline $68.50 (£47.06) for the 260-mile journey.

  The one-hour flight costs the airline an estimated $2.50 per passenger [for fuel].

The total cost equals \$10,549 per hour "with profits as low as \$10 [per passenger] on some flights".

Also from the article—

  If you want to be a millionaire, start with a billion dollars and launch a new airline.— Sir Richard Branson


The same system which populates all the data on displays in a Railway Terminal.
For a standalone airport, this data can be mined from ATC of that airport (Which has all the data regarding incoming/outbound flights ).
On an International scale, the data has to be mined from various different agencies. According to a data provider FlightStats:
It gets data from:

Complete, accurate data is the cornerstone of our business and what
sets us apart from competitive solutions:
Geographic Coverage - FlightStats provides definitive information for approximately 99.5% of U.S. flights, and better than 86% of
flights worldwide.
Completeness - FlightStats queries multiple sources to create a record for each flight enabling us to offer a broader range of
information (for example, gate information).
Accuracy - We have invested heavily in the areas of parsing, interpretation and error checking and developed the logic that enables
handling of difficult issues such as cancellations, diversions and
changing schedules.
Codeshare Support - Our codeshare logic enables us to deliver flight information for both the operating and the marketing carriers,
filling what is often a major gap in coverage.
Real-time data sources include:
FAA ASDI Data Feed
European Data Feed
GDS (Sabre, Amadeus, Apollo, Galileo)
Direct Airport / Airline Data Feeds

Batch data sources include:
Innovata Schedules
TSA Security Wait Times
Security Information
Health Information
Consular Information

For the system which gets all this data from various different sources, its the central computer database of the airport, which gets data from ATC and the a fore mentioned sources, and this database is accessed by many other end users, including the Screens in the airport


Judging from this video, it does not have an automatic prop sync. When throttles are advanced you can hear the harmonic beat of the twin propeller blades, and during the climb the instructor seems to manually set the levers to reduce the harmonic set the correct manifold pressure. He may or may not have an indicator to help him, but judging from the sound effects there is no automatic synching taking place.

And here is an old C-47 cockpit procedure training film, on how to fly the aircraft. Nothing on synchronising the propellers.

That beautiful engine sound is not produced by a turbine by the way.


There are no spinning parts in the VOR.

It typically uses 60 antennae in a phased antenna array to steer the beam in a rotating sweep.

The VOR transmits a constant omnidirectional signal.  The phase of the secondary sweeping directional beam is varied in time such that it is out of phase with the constant signal by the same number of degrees from North.  The receiver measures the phase difference between the constant and sweeping signals to determine its bearing from the transmitter.


What is a compounding wing and how does it increase helicopter performance?

This paper discusses wing compounding and appears to be a free PDF download.  Apparently the added wing provides lift to offload the rotor, allowing them to work more on providing forward propulsion and relieving some of their need to also create lift.  Figure at the top of page 6 shows the helicopter with added wing with outboard props on the wing.

  The compound helicopter configuration, known as the hybrid compound helicopter, features both wing and thrust compounding. The wing offloads the main rotor at high speeds whereas two propellers provide additional axial thrust as well as yaw control. This study investigates the maneuverability of these two helicopter configurations using inverse simulation. The results predict that a hybrid compound helicopter configuration is capable of attaining greater load factors than its conventional counterpart, when flying a Pullup-Pushover maneuver. In terms of the Accel-Decel maneuver, the two helicopter configurations are capable of completing the maneuver in comparable time-scales. However, the addition of thrust compounding to the compound helicopter design reduces the pitch attitude required throughout the acceleration stage of the maneuver.


What is the mathematical relationship between Specific Excess Power and an aircraft's acceleration at a given point on an E-M diagram?

You forgot that you accelerate not from standstill, but a considerable speed. So that equivalent potential energy change comes on top of the existing kinetic energy and makes the energy change look much smaller (resulting from the square of speed in kinetic energy). The correct calculation is
$$\frac{\delta E_{pot}}{\delta t} = 800 \;\text{ft/sec}\cdot g=(v_1^2-v_0^2)\cdot \frac{1}{2\cdot \delta t}$$
Your acceleration will decrease as speed increases. If I assume a speed of 800 ft/sec, the resulting acceleration is to a speed of
$$v_1 = \sqrt{v_0^2+2\cdot g\cdot h} = 831.55\;\text{ft/sec}$$
within one second which is 31.55 ft/sec² or just shy of 1 g. The initial acceleration is 1 g and decreases as the aircraft picks up speed. In mathematical terms:
$$\ddot x = SEP\cdot\frac{g}{v} = v_z\cdot\frac{g}{v}$$
When climb speed (or specific excess power) equals flight speed, both cancel, leaving gravitational acceleration equal to horizontal acceleration if all climb potential is used for increasing speed.


Can Transition Altitude (TA) and Transition Level (TL) be equal?

The TA and TL will always be at least 1000ft apart to ensure that aircraft flying at each will always be properly separated.
The TA will be a fixed value to ensure terrain and obstacle clearance, while the TL will be the lowest reasonable value that provides this minimum vertical separation above the TA. However, “reasonable” includes not having any possible numerical ambiguity.
So, if your TA is 8000ft, then the lowest possible TL is FL085. Depending on the QNH, though, the TL may be higher.


How can the A320 receive 3 DME signals if it has only 2 DME receivers?

Mighty interesting! There is a clue in the FCOM:
Four frequencies per FMGC
If you check FCOM Chapter 22 § 20-20-30 you'll note it says:

Each FMGC [Flight Management and Guidance Computer] automatically uses its four DME frequencies as follows:

One DME frequency for display. It is possible to tune it manually or automatically. This DME frequency is also used for VOR/DME position
computation.

Two DME frequencies in DME/DME mode for calculating the radio position of the aircraft. The FMGC automatically tunes these as a
function of their best accuracy. The flight crew does not receive any
indication that this process is happening.

One DME frequency is connected to the ILS/DME.

Note my bold emphasis above. Similarly for the A380, in clearer language:

In normal operation, each FMS can tune four DME s at the same time. (...)

Scanning DME
Wikipedia says:

Scanning DME (distance measuring equipment) that check the distances from five different DME stations simultaneously in order to determine one position every 10 seconds [emphasis mine]
—Wikipedia: Flight management system § Position determination

The patent for this scanning-type DME was filed in 1982:

(...) a scanning type DME unit which is rapidly sequenced to interrogate said multiple ground stations successively and determine distance thereto for all stations within range, and a computer to validate and process these distance measurements in sequence to provide an accurate computation and display of aircraft position and wind information. [emphasis mine]
—Meyer, Donald H. "Accurate DME-based airborne navigation system." U.S. Patent No. 4,583,177. 15 Apr. 1986.

Failure scenario
Regarding the failure scenario, each FMGC can tune both its interrogator, and the other interrogator if the other FMGC failed.[1] Each FMGC is still limited to four frequencies though. So, if one DME fails (antenna or its interrogator), you'll have two frequencies which you can control (one for display, and one for ILS), and two the FMGC will use for DME/DME position, but you can't have two different DMEs for display.
1: Airbus Single Aisle Training Manual ATA 34


What are ICAO English language requirements?

ICAO defined a framework of language proficiency levels for aviation. It ranges from level 1 ("Pre-elementary") to level 6 ("Expert" / native speaker). Level 4, "operational", is the minimum required for flight crews. Many airlines require at least level 5 from their pilots.

Native speakers can get level 6 with a simple proof of that they're a native speaker (I heard recently that e.g. for a German license the authorities see it as sufficient if the person visited an English speaking school). Non-native speakers do assessments to certify their language proficiency. An assessment for level 4 has to be repeated every 3 years, level 5 lasts 6 years and level 6 is life-long.

For languages other than English, there are assessments / language proficiency certifications that are regulated by country-specific authorities and it's practice in at least some countries that native speakers can get their native language put into the license as level 6.

There are detailed requirements for each level (e.g. pronunciation, vocabulary etc.), they are usually presented in a big table:


Did the Space Shuttle really wait until 50 feet above the ground before they put the gear down?

If you're looking for a definitive source, how about the Shuttle Crew Operations Manual. It's essentially the POH for the Space Shuttle. Secton 2.14-2 says:

  The landing gear is deployed at 300 ± 100 feet and at a maximum of 312 knots equivalent airspeed (KEAS).

Although, the targeted deploy speed was 288 KEAS according to the Normal Procedures section 5.4-7, which matches up with approximately what you see in HUD videos.

The manual says the gear may take up to 10 seconds to fully deploy, but based on HUD videos (measuring the time it takes for //GR// to change to GR-DN), this process pretty consistently took about 6 seconds and was completed by about 70-130 feet AGL depending on the deployment altitude.

The reason they deployed so late is because the shuttle was a very non-aerodynamic "airplane" to begin with, and lowering the gear would reduce its lift-to-drag ratio even further. However, there were non-standard procedures in place (see section 7.4-25) where, if the speed brake (a split rudder – not a wing surface) was stuck closed, they would have lowered the gear earlier in order to act as a speed brake. Note that the hydraulic system was incapable of raising the gear in-flight, so once down, it stays down.

Because the shuttle was a "glider" (a generous use of that term) at landing, with no chance of going around, the gear absolutely must work on the first try. A shuttle belly landing would have ended very bad due to its high speed and high angle of attack. In order to assure the gear would extend, there were several redundant systems in place:

The doors had a bungee-assist system which exerted 2000 pounds of force (~9 kN) on the nose wheel doors, and 5000 pounds (~22 kN) on each of the main wheel doors.
The nose wheel had a pyro-assist system which fired every time the gear was deployed, and helped assure it would lock into place.
The gear is normally deployed through a combination of "springs, hydraulic actuators, aerodynamic forces, and gravity."
However, if all else fails, and the gear does not begin to move within 1 second of issuing the command, a pyrotechnic initiator cuts the locks and forces the gear down.

So they were pretty confident it was going to work.

Interestingly, the original procedure for deciding when to deploy the gear was based on airspeed, not altitude. However, this resulted in an inconsistent safety margin. This quote from the Flight Procedures Handbook: Approach, Landing and Rollout explains it better (sorry, I don't have a link to a doc, I probably downloaded it from a nasaspaceflight.com forum a few years ago with a paid membership):

  The landing gear deploy cue for STS-1 through STS-4 occurred when the velocity decelerated through 270 KEAS. This corresponded to an altitude of 200 ft on the nominal energy trajectory. Flight STS-1 followed the velocity cue procedure which, due to its much higher than expected energy, did not occur until an altitude of 85 ft. Had the gear been deployed at 200 ft, some of that excess energy would have been dissipated. Flight STS-2 was very low on energy, reaching a maximum velocity of only 274 KEAS at 1100 ft altitude. The 270 KEAS cue occurred at 600 ft, but the actual deploy occurred at 400 ft, adding to the already existing low energy condition. Lower energy occurred since the nominal altitude for gear deploy would have occurred at 200 ft on a nominal trajectory. Flight STS-3 was high on energy, not decelerating through 270 KEAS until an altitude of 87 ft. T/D occurred earlier than expected on STS-3 and the gear was actually down and locked only a couple of seconds before first wheel contact. It was after STS-3 that altitude was selected as the gear deploy cue because it would compensate for off-nominal energy conditions, not make them worse, and still satisfy safety concerns. Downrange was also considered as a gear deploy cue, and it too, had advantages over velocity.

As far as the sign you are referring to, I see three possibilities:

They were referring to the very early missions which sometimes saw very late gear deployment,
They were rounding down for dramatic effect, or
They simply made it up on the spot as if it were a statistic.


What is the production status of the Pipistrel Panthera as of March 2017?

I may have more news on that next week from Sun 'n Fun 2017.  Pipistrel will be an exhibitor at the show and may have a Panthera prototype on display.

Currently the Panthera is planned to be released as an experimental kit and may be type certified at some point in the future.

I know the program has suffered some setbacks, including an increase of empty weight by some 200 lbs.  New aircraft development is never fast nor without complications.

The Panthera does look intriguing - 200 KIAS on 10 GPH with good, stable flight characteristics and modern avionics, BRS parachute, etc.  I want to take it for a demo flight when production examples become available.


Can jetliner pilots program departures when specific RNAV procedures do not exist?

A Boeing 737 uses a Flight Management System (FMS, see this question for details: What's the difference between FMS and FMC?). This FMS takes inputs from multiple navigation sources/sensors, including inertial, radio, and GPS. One part of this system is the CDU (Control and Display Unit, actually there are two installed), which is one of the interfaces to the FMS:

(source, this is from a simulator, real one looks similar)

On the page in the image above, the departure runways and SIDs for EDDK are shown as an example. The pilots can select the departure procedure that was assigned to them by ATC. This assumes the flight is conducted under Instrument Flight Rules (IFR), but since you asked about commercial operations this will almost certainly be the case.

A departure procedure without any specific RNAV waypoints (e.g. fly runway heading, then radar vectors) will still be selectable in the CDU. An item VECTORS will be displayed on the LEGS page between the departure runway and the first enroute waypoint. Once ATC clears you direct to a waypoint, the CDU can be easily updated by moving this waypoint to the top.

It is also possible to manually enter waypoints into the LEGS page if a pilot chooses to do so. The 737 CDU allows creating pseudo waypoints e.g. by giving a reference waypoint, a distance in NM and a course. This way, a more accurate route can be shown on the Navigation Display (ND). However, when getting radar vectors from ATC it is more likely the pilots will fly using HDG SEL (Heading Select) rather than following waypoints programmed into the FMS using LNAV (Lateral Navigation).


Why and how were "eybrow windows" helpful in tight turns?

In a (steep) turn, airplane is actually flying partially upwards relative to the cockpit directions. It is simply because the turn is (usually) flown with more-or-less constant altitude, but the airplane is significantly banked, so plane of motion intersects cockpit in the same, bank, angle.
So these windows are located approximately in the direction where you are just going. As long as you see only sky there, everything is fine and as it should be. :) But would there be an another airplane, you really want to see it while there is still time to avoid a collision. Whatever you see through front window during a steep turn is either not on your flight path at all or about to collide with nose in nearest following seconds.


How do AHRS systems meet the "gyroscopic" requirement of 14 cfr 91.205.d?

In regulations, instruments are always defined functionally. They say what the instruments must measure, not how. Any actual implementation then has to be certified, but that certification concerns with accuracy of the instrument, its reliability and ability to detect its failure – because the pilot can only handle the failure if it is obvious to them – not it's principle. So anything that can locally (without external reference) measure attitude and rate of turn qualifies.
Note that the "gyro" root does mean “circle”, but don't forget the other half of the word:

[…] from Ancient Greek γῦρος (gûros, “circle”) and σκοπός (skopós, “watcher”).[1]:

It means, and always did, an instrument for observing rotation, though it was only used to describe one of the methods for doing so known to the person that coined the term (that person was Leon Foucault and the other method was obviously Foucault pendulum).


How to select the most efficient airfoil for low speed flight?

Please read the answer to this question first and try to answer the questions listed there. You need to provide more information!

Next, the best place to look is among glider airfoils. The Wortmann FX 63-167 is now 55 years old but still a good start. It was designed for the low speed of a human powered aircraft and has been used on gliders and motor gliders.

But the airfoil still can be improved, for example by adding flaps or by narrower tolerances for the surface contour, especially around the nose. But this will make construction more complicated, so the overall best compromise might still be the Wortmann airfoil.


Can two opposite localizers to a single runway be on simultaneously?

ICAO Annex 10 Volume 1 has the answer:

  3.1.2.7 At those locations where two separate ILS facilities serve opposite ends of a single runway, an interlock shall ensure that only the localizer serving the approach direction in use shall radiate, except where the localizer in operational use is Facility Performance Category I — ILS and no operationally harmful interference results.

In plain language: only one localizer can be on at a time, unless the ILS in use is only CAT I and it has been confirmed that no harmful interference will happen.


What are these acceleration parameters produced by the Inertial Reference System?

I can't be sure without seeing actual documentation of the thing, but I would expect:

Flight path is direction of the total velocity vector, i.e. the direction the plane is flying, in Earth-relative frame of reference. This differs from direction of longitudinal axis by alpha (angle-of-attack), beta (side-slip) and wind.
Track is projection of flight path to horizontal plane.
Heading is projection of the longitudinal axis to horizontal plane.

Then:

flight path acceleration would be simply acceleration along the flight path
along track and across track are, well, along and across track as defined above.
vertical is vertical; should not include gravity, so when maintaining vertical speed it should be 0.
unbiased normal acceleration is most probably what is also called inertial normal acceleration, that is acceleration without gravity.
along and across heading are, well, along and across heading as defined above.


Is it possible to do linear interpolation on a manual E6-b?

My advice in this case would probably be: Once you know the density altitude, don't bother with the flight computer. The exact values are going to depend enough on the specific airplane that a general-purpose device will only get you approximations anyway, no matter what you do.

Rather, consider that for your fictious case, when going from a density altitude of 0 feet to 2,000 feet, takeoff distance increases from 1,865 feet to 2,602 feet.

Split the difference into reasonable, approximately equal-sized chunks. Say density altitude 0 ft, 700 ft, 1,400 ft, 2,000 ft. Calculate take-off distance for those, possibly based on a linear extrapolation (which isn't going to be exact), and note the change in take-off distance per change in density altitude. In your example case, for every 700 ft of density altitude increase in this range, the take-off distance increases by about 250 ft. Alternatively, for every 1,000 ft of density altitude increase in this range, take-off distance increases by about 370 ft. (If you're in a metric country, this happens to work out nicely to a little over 100 meters of runway per 1,000 ft of density altitude increase, so for a first order approximation you could just cross over the final digit in the density altitude in feet.) Note these values.

Now suppose that the density altitude for your airport of choice on the day and time of your flight is 1,370 ft. That's reasonably close to 2,000 ft minus 700 ft, so take the take-off distance for 2,000 ft (2,600 ft, give or take) and subtract 250 ft to get an approximate value of 2,350 ft take-off distance for this density altitude.

Or suppose the density altitude is 491 ft. That's closer to 700 ft than it is to 0 ft, so take the take-off distance for 0 ft (1,865 ft) and add 250 ft. That gives about 2,100 ft take-off distance. If you split into thousands, you could take half of 370 ft or about 200 ft, for a hair over 2,050 ft take-off distance.

For your example case, if the last hundred-ish or so feet of runway are going to be what makes or breaks the take-off, then I suspect you're cutting it too close anyway, so this level of accuracy should be sufficient for general aviation. With this, I'd probably have a rule of my own saying that if the runway length is less than, say, 150% of the calculated take-off distance, it needs a more accurate calculation or manufacturer performance data lookup; if the runway is less than 125% of the take-off distance thus obtained, it's a no-go. Remember that you have to be able to safely abort the takeoff even late during the takeoff roll!


What does "airspace above 14,500 MSL is controlled with few exception" mean?

Class E airspace starts at 14500 feet MSL except for the airspace below 1500 feet AGL or designated and charted to start lower (SETVODA). There are areas like the US Rocky Mountains that are more than 13000 feet in elevation.

Class E is controlled airspace. Sectionals and charts will give you the information for the controlling agency. But just as if not more important, the minimum VFR weather requirements have to match those of controlled airspace (3-152, 5-111).

§71.71 Class E airspace.
Class E Airspace consists of:

(a) The airspace of the United States, including that
airspace overlying the waters within 12 nautical miles of the
coast of the 48 contiguous states and Alaska, extending
upward from 14,500 feet MSL up to, but not including 18,000
feet MSL, and the airspace above FL600, excluding—

(1) The Alaska peninsula west of longitude 160°00'00" W.;
and
(2) The airspace below 1,500 feet above the surface of the earth.


How can an airliner make up for time lost?

That's a common scenario, that you're pushing off the gate late and would like to make up time.  There are a number of ways that making up time can happen, although how much of that the pilot can affect doesn't often amount to a huge impact.

The flight is scheduled for whatever length of time, gate-to-gate.  This accounts for the sorts of delays that the planners foresee when they're building the schedule: it's winter, so the aircraft may need to be de-iced.  It's a busy time of day, so they plan on a slower taxi than simply driving out to the runway & taking off.  The flight is usually scheduled around a moderately worst-case headwind/(lack of) tailwind.  And so for the 1+00 (in the air) flight, you might be scheduled for 1+30 gate-to-gate.

And if some of the negative factors don't materialize, then you'll under-fly the schedule, which is nice.  Maybe the delay at the gate caused you to miss the "morning rush hour" and you did get to taxi right out, no line or delay, and take off.  There's no precipitation, so no delay for de-icing.  The tailwinds are better than average today, so instead of 1+00, your flight will only be 0+55 in the air.  All good things!

But none of that is really under the pilot's control.

The two places that the pilot can most affect things are, going faster, and getting shortcuts.  Going faster essentially means using more gas, and sometimes guys are willing to do that... the high-school tour group is in danger of missing their connecting flight & being stranded in the hub for the night, let's go fast & get them there!  Another version of going fast is flying at a more "speed efficient" altitude, usually around FL290 or FL300.  If winds are all the same, you'll generally get more speed there because your maximum indicated airspeed (Vmo) and limiting Mach number (Mmo) are very close around that altitude.  The tradeoff is, however, that you are burning more gas by doing this compared to going higher.

If you have the gas to burn, this can typically work.

Also, you can request shortcuts.  Depending on the filed route and what's going on in the airspace, this may get significant savings.  From the West Coast to DFW or IAH, you're typically routed around the north or south side of White Sands.  But, if it's Saturday night and the restricted area is cold (not in use), then you may be cleared direct right through it & save some significant time.  Of course, requesting shortcuts also saves gas (unless it takes you off a wind-optimized route -- rare but possible), so there's no real reason not to do it on every leg.

ATC may or may not cooperate with your plans.  If the restricted area is hot, then you don't get the shortcut through it.  If you're inbound to a busy terminal area (DFW, LAX, IAH, BOS, etc) then ATC probably has a sequence in mind, and they won't approve anything that changes the orderly flow of aircraft into the arrival.  In fact, they may assign you a speed in order to fit the sequence together.

Other than that sort of planning, though, they typically don't mind if you fly fast, and if they aren't too busy, ATC usually approves requests for shortcuts that don't have you driving through restricted areas (or other special use airspace).

How much time can you make up as a pilot?  If you really want to burn the gas, you might make up 5-10 minutes by going fast on a typical 1-2 hour flight, but those extra minutes are getting pretty expensive when you do that.  Shortcuts may give you another 5 minutes or so, in the best case.  (Longer flights tend to be more direct, as a % of the time, so you can't get the bigger & bigger time savings on the longer flights with shortcuts as you do with speed, compared to the short flights.)

But when a pilot tells you that he's going to make up 20 minutes off the planned flying time, most of that will probably be already baked in (tailwinds, no delays, etc) rather than things that he's doing differently than he otherwise would.  (It's still a nice line on the PA, though.)

And some days, none of the above works the way you hope, and the late flight doesn't get any earlier, or even gets later, despite your best efforts.  Speed, time, and distance can just be a bear, sometimes!


Was NextGen simulated/tested against alternatives?

NextGen is an FAA programme that strives to modernise America's air transportation system to make flying  safer, more efficient, and more predictable.
NextGen is not one technology, product, or goal. As such, you can't test NextGen against an alternative.
Also the major benefit of ADS-B is not that it providing faster updates or that it is cheaper. It allows for a paradigm shift in ATC.
Separation minima in the TMA are not primarily driven by surveillance performance. They are driven by the latency in the chain from surveillance -> interpretation of situation by controller -> deciding resolution of situation by controller -> communicating instructions to affected aircraft -> pilots implementing the instructions -> aircraft reacting to pilot commands. Wake turbulence is another driving factor. Surveillance update rate is a minor factor in all of this.
The more aircraft there are in an area, the more the controller needs to monitor and to communicate, the more critical the separation becomes. We are reaching a fundamental barrier which can't be solved by adding more air traffic controllers. The only way to break that barrier is to automate some of the functions the air traffic controller performs in the Air Traffic Control System, or to offload them to the cockpit. ADS-B is an enabler for that.
ADS-B allows for the development of a Cockpit Display of Traffic Information (CDTI), increasing the situation awareness in the cockpit and thereby improving safety.
ADS-B enables applications like Cockpit based Interval Management, where the pilot receives speed and heading instructions from a system based on ADS-B in order to achieve a spacing distance or spacing time with respect to another aircraft, taking workload of the air traffic controller while achieving a higher arrival throughput.
ADS-B enables CDTI Assisted Visual Separation (CAVS), which will allow airport to achieve visual arrival rates in marginal visual meteorological conditions.
ADS-B allows for new types of TCAS, reducing the RF overload on the radar frequencies that are congested in some area. (Your suggestion of just adding radars on every runway end is probably achieving the opposite of what you want. It causes transponder overload and a very poor update rate as a result)
ADS-B allows for space based surveillance, providing global coverage and thereby improving safety and efficiency on oceanic flights.
I am sure alternatives were discussed. Some applications did not make it through the whole process, others did. But ADS-B, conceptually, is fundamental to the many of the changes in NextGen. That is not to say that ADS-B is perfect, or even good. On the technology level it could be a lot better and for example a lot more secure. But it would have costed a lot more too.


Advantages and disadvantages of air intakes above fuselage/wings in jet fighters?

Advantages of overwing intakes:

Little danger of foreign object damage (FOD). Remember that F-16 bases need to keep their runways spotless in order to avoid FOD. The low intake will hoover up all loose items around it while the overwing intake mainly sucks in air from above.

Disadvatages of overwing intakes:

Lower pressure recovery at high speeds. The air above the wing is first accelerated in order to create lift and then this accelerated air must be decelerated for maximum pressure recovery. This is less direct and incurs more losses than low intakes which operate in pre-compressed air.
Operation in low density air in supersonic flight. Especially when thrust is needed most, at high angle of attack, an overwing intake will feed the engine with lower pressure and lower density air, reducing the available thrust.
Noise: The North American F-107 was said to be the loudest aircraft from the pilot's perspective, and cockpit noise was one reason why it did not enter production. Granted, here the intake was not over the wings but on the upper side of the fuselage, right aft of the cockpit, but I thought I include this item here nonetheless.

Early stage of F-107 development (picture source), at this time called the F-100 B, but the low intake interfered with weapons release from a central belly bay …

… and that is how it turned out eventually with the re-located intake (picture source)


Are you mandated to use a Fault isolation manual when clearing a defect on an aircraft?

FIM contains procedures for both A/C systems (E.G. EICAS, ECAM, CPDS) messages and pilots/maitenance observations (e.g. smell of burning oil, windshield delamination).
All kind of reasonably possible faults should be covered by FIM.

Just simply use yor FIM preambule to determine if it specifies what to do when fault is not covered by FIM and to determine either mechanic judgement or OEM (A/C manufacturer)contact is requied in such case.
If such information is not included contact OEM.


Do aerodynamic forces and moments change aircraft pitch and yaw in the same way?

Of course will yaw also change direction if we define this as a change in the flight path. But it does so much less efficiently than banking.

Yaw creates a side force on the fuselage and fins which accelerates the aircraft sideways. This does change the resulting flight path, but the amount of side force is small due to the low aspect ratio of the fuselage. The lift-to-drag ratio of the fuselage is poor, so another change to the aircraft's vector is a deceleration if the increased drag is not compensated by more thrust.

Banking also creates a side force (when seen in the geocentric reference system), but now the wing is responsible for that force. Its lift-to-drag ratio is much better than that of the fuselage, therefore, the amount of side force is much higher and less drag is created. By first banking and then pulling more than 1g, the pilot changes the flight path much more effectively while maintaining altitude.

So the answer is yes, yaw behaves the same way as pitch. Only the wing and elevator are replaced by the fuselage and fins, with all changes to the magnitude of the forces this causes. The only difference is that pitch is needed to adjust lift, and changing the pitch attitude will change the speed of the aircraft or the load factor. Flying in a sideslip with no adjustment for the side force by a corresponding bank angle will continuously accelerate the aircraft sideways and will result in a uncoordinated turn. Now the sideways load factor (which is zero in coordinated flight) will be nonzero while in the longitudinal motion the normal size of the load factor is one (and be different from one when pitch is changed).

EDIT:

@TomMcW has contributed a practical example in the comments. Consider a crosswind landing with a glider or motor glider where crabbing is your only option to fly a straight approach over ground. Right before touchdown you should then step on the rudder to align the aircraft with the runway so the tires can touch down without moving sideways. Now consider that you stepped on the rudder too early and the aircraft floats along the runway with a sideslip angle. You will drift leewards, right? That is exactly the change in flight path I am talking about.

In crabbed flight the aircraft flies without sideslip. The fuselage with its forward center of pressure position destabilises the aircraft in yaw and the vertical tail adds the required stability. Both create no side force in crabbed flight. Now you want to align the fuselage with the runway and step on the rudder: The tail swings the aircraft around into a sideslip until the fuselage points into the desired direction. Now opposite rudder must be applied briefly to stop the yawing motion and then returned to a position between neutral and the initial deflection in order to trim the new sideslip. Note that this works exactly in the same way as the elevator when a new angle of attack is trimmed!

In the sideslip condition both the fuselage and the vertical tail will create a side force in the same direction. The side force of the fuselage is higher because its center of pressure is closer to the center of gravity than that of the tail, and in order to reach an equilibrium, both must point to the same side. This combined side force accelerates the aircraft sideways such that a speed component is added which reduces the sideslip condition. Since the aircraft is trimmed for a specific sideslip, the changing balance of moments with a change in sideslip will yaw the aircraft further so that the trimmed sideslip angle is restored.

Why is that? Remember that the rudder is deflected. This creates a camber in the vertical tail which moves its zero-sideforce angle of sideslip away from the sideslip angle of zero to a negative angle (for example, right rudder deflection will shift the zero-sideforce sideslip angle on the tail to a left sideslip value). Any change in sideslip will, therefore, bring a relatively larger change in side force at the tail which changes the balance of yawing moments such that the old sideslip is restored. Note again how similar this is to static longitudinal stability.

This means that the aircraft must maintain a slow yawing motion in order to keep the sideslip constant. The side force causes a reduction in sideslip and the yawing motion is a result of the sideslip-maintaining tendency of the vertical tail.

And, no, yaw is not a moment. Please let's all use an agreed version of English.


How much force can the landing gear of a Piper Arrow withstand?

The Arrow is certificated under 14 CFR 23, and the landing gear loading limits are specified in the ground loads and landing gear sections. I don't know much about this subject and the regulations are fairly technical, but 23.473 apparently defines the load limit. I don't really understand it myself, but it looks like the landing gear has to support at least 2.67 times the aircraft's weight in a landing:

  No inertia load factor used for design purposes may be less than 2.67,
  nor may the limit ground reaction load factor be less than 2.0 at
  design maximum weight, unless these lower values will not be exceeded
  in taxiing at speeds up to takeoff speed over terrain as rough as that
  expected in service.

In reality they should be designed to withstand more than this, as there are manufacturing uncertainties which can affect a component's performance.

Someone who's actually an engineer could probably explain it better (or correct me, as the case may be!).

As for testing, my limited understanding of the certification process is that the manufacturer has to prove to the FAA that the requirements in part 23 have been met, but there's no specific way of doing that. And indeed, 23.721(c) says:

  Compliance with the provisions of this section [i.e. the landing gear section] may be shown by
  analysis or tests, or both.


Is it possible to maintain horizontal flight with the angle of attack above critical value by increasing speed?

That is kind of what the mechanism of lift of a flat plate does: the sharp leading edge destroys the upper flow pattern almost immediately. This question has more info on it.

The lower side of the wing does provide as much or more lift, even when stalled, at AoA of 45°, so lift would not be the problem. Drag would be:

Image source

On this scale, drag for the NACA 0012 profile is very close to zero until the aerofoil stalls, after which it jumps up and continues climbing. At AoA of 45° the C$_D$ is 1.1 instead of about 0.02 when not stalled - you need over 50 times the thrust to maintain the stalled condition you are describing!


How can I use the "control hinge-moment coefficient due to tab" for sizing a trim tab on an elevator?

The trim tab is sized first, and then the tab hinge moment is computed. The trim tab is sized to the conditions required for maximum trimmed position of the aircraft at:

low speeds;
all relevant CG positions;
all relevant flap settings;

The contribution of the trim tab to the elevator hinge moment is tiny, see the right hand graph which is measured data from the F-27.


Does the F-16's neutral stability also extend to the negative-G flight regime?

The F-16 is unstable at low speeds, and stable at higher Mach numbers. It has a flight control computer though, which stabilizes the aircraft using the feedback from pitch rate (so from the view of the pilot an F-16 acts similarly as a stable aircraft). This applies to both positive and negative attitude disturbances, so for both + and - G loads perceived by the pilot.


How can a CFI renew their certificate with the FAA?

14 CFR 61.197 lists renewal requirements for flight instructors.

If your CFI certificate is still valid (unexpired) than you can renew by any one of the following:

Getting a new rating on your CFI certificate or re-taking a practical test for an existing rating on your CFI certificate

  (1) Passing a practical test for—

  (i) One of the ratings listed on the current flight instructor certificate; or

  (ii) An additional flight instructor rating; or

Having had at least 5 students in the last 2 years with an 80% or higher pass rate

  (i) A record of training students showing that, during the preceding 24 calendar months, the flight instructor has endorsed at least 5 students for a practical test for a certificate or rating and at least 80 percent of those students passed that test on the first attempt.

Being a check pilot, chief flight instructor, check airman or flight instructor for a part 121 or 135 operation and active in pilot evaluation during the last 2 years

  (ii) A record showing that, within the preceding 24 calendar months, the flight instructor has served as a company check pilot, chief flight instructor, company check airman, or flight instructor in a part 121 or part 135 operation, or in a position involving the regular evaluation of pilots.

Completing an approved refresher course within the preceding 3 months

  (iii) A graduation certificate showing that, within the preceding 3 calendar months, the person has successfully completed an approved flight instructor refresher course consisting of ground training or flight training, or a combination of both.

Passing a US armed forces military instructor proficiency check in the preceding 12 months.

  (iv) A record showing that, within the preceding 12 months from the month of application, the flight instructor passed an official U.S. Armed Forces military instructor pilot proficiency check.

If you are not actively instructing and just maintaining your certificate the easiest method is the approved refresher course.  There are a few weekend workshops and a online courses that are approved.  The last time I did this method I used an online course and submitted the 8710 via IACRA and completed the whole thing over a weekend and with no physical paperwork.

If your certificate has expired, even if you have completed the above but failed to submit the proper paperwork in time, then you can no longer do this the easy way and have to look at 14 CFR 61.199.  To reinstate an expired certificate you must either pass a practical test for one of your existing CFI ratings or pass a practical test for a new rating for your CFI certificate.


Is there anywhere one can buy or find plans to build a human powered aircraft?

Yes, contact Todd Reichert, PhD, or Cameron Robertson at Aerovelo Inc.   They have designed, built, and demonstrated the first human powered vertical aircraft at the University of Toronto, of which they are alumni, and they won the Sikorsky prize of $250,000 for it.

They have aero-velomobiles that can smoke the albatross.

Note: The ability to get airborne in these Ultralights is heavily dependent on the weight and athletic ability of the human operator.


High wing planes typically have less dihedral than an otherwise comparable low wing design, because of keel effect: they have more righting moment for a given dihedral angle because the fuselage hanging below the wing increases pressure near the wing root on the low side when a bank induces slip.

The value of the dihedral can be low enough that the wing may look flat (Piper Cubs and Taylorcraft look flat, to me), but if you build a high wing airplane with genuinely zero dihedral, the wing will appear to droop (take a look at period photos of Lindbergh's Spirit of Saint Louis).

Dihedral is present in nearly all high wing aircraft, for the same reason it's present in nearly all low wingers -- because it tends to support or raise the low wing when a bank without coordinated rudder causes side slip.  This produces lateral stability, which in turn makes the airplane easier to fly.


What are the FAA currency requirements for a foreign based certificate?

If you have that situation, you should ask FAA's Office of Chief Counsel. There is no univocal position about that.

The first position is that your EASA license should not be expired (which is not a case because EASA licenses do not have expiration date) or revoked, and should not list explicit limitations (according to Krauzs 2012 and Grossman letters). In that case your 61.75 license is good to go even with expired ratings in the EASA one. The only limitation is a current medical (because the license is invalid without it).

The second position is that all your EASA ratings should be current too, so they can be considered as limitations of your EASA license.

The second position is just safer. Nobody will have questions to you: neither FAA inspector, nor an insurance company.

In any case, it is required to be current by the FAA rules (BFR, medical, approaches/holdings etc.). For example, here (especially see Dave's comment) one had a problem with foreign-based license without current US medical.

In your case I would take FAA tests and obtain a standalone license, and forget about the problem (it's what I actually did recently). If it is not an option, either keep your EASA license current (just in case) or request an official answer in paper from the FAA.

Related topics on pprune: here and here.


Aircraft are not always moved with tugs (the small vehicle you refer to). Much of the time, they operate under their own power.

Airliners are generally pushed back from the gate using a tug, as that's the simplest and most efficient method. They then taxi to the runway (and all the way up to the gate, after landing) using their own engines to provide thrust. This is true of both jets and propeller aircraft.

Some work is being done on self-contained electric-powered ground propulsion; one major player in this area is a company called WheelTug. They use high-torque motors and the aircraft APU to allow the aircraft to move itself without starting its engines or requiring a tug to be connected and disconnected.


What does the ACARS Weight and Balance Request page look like?

As you said, it will vary by airline. Mine has a few screens, and the pilots enter in number adults and children in each seating zone, number of total infants, number of standard and heavy items in cargo, any additional weight in cargo (shipping cargo, mail, ballast, etc). Also the desired runways to get data for and their condition (dry, wet, snow, etc).
Many, sometimes all, of these items are auto-populated when the gate agent closes the flight, except for the desired runways.
When the response is received, it contains weights and center of gravity numbers, and then each runway will have specific thrust (temperature, ECS/bleeds, flex, and target resulting thrust) and flap settings, as well as the V speeds.


If an airplane touches down short of the runway, and doesn't reach it, is it still a runway excursion?

It depends.

Skybrary says

  The Runway Excursion category includes also two types of occurrences which do not fit the ICAO ADREP definition for a runway excursion, however considered appropriate for inclusion due to the commonality of a number of causal and contributory factors and/or mitigation approaches:

  An aircraft attempting a landing touches down in the undershoot area of the designated landing runway within the aerodrome perimeter.
  A runway or taxiway other than the designated one is used for a take off or a landing.

My emphasis.

The European Commercial Aviation Safety Team (ECAST) in the European Strategic Safety Initiative (ESSI) use the Skybrary definition when writing about Runway Excursion Prevention

  Articles within the Runway Excursion Category in SKYbrary:

  Overrun on Take Off
  Overrun on Landing
  Directional Control
  Undershoot on Landing
  Wrong Runway

My emphasis.

In an article "Language and safety issues" in Eurocontrol's magazine in 2011, Bert Ruitenberg wrote:

  The whole idea of putting a label such as “runway incursion” or
  “runway excursion” on a safety occurrence is to make it easier to
  file the data from the event somewhere and to compare it with
  similar occurrences. With the definitions above, a take off from a
  taxiway would be considered as a Runway Excursion when the
  Skybrary definition is used, but not with the other RE definitions
  (and rightly so, I say, better label it a “taxiway take off”). Moreover,
  in the ICAO definition, the B777 undershoot at Heathrow
  would not be a RE, but with the Skybrary definition it would be.
  Dear Safety Managers of the world, there still is a lot of work to
  be done...


The current position of regulators like the FAA is that dropping things off of airplanes in flight is a bad thing. Dropping extremely large and heavy things like engines would be extremely bad. This poses an unacceptable risk to people and property on the ground (or even in the water). Most aircraft with engine fires do not kill anyone on board, so why risk killing people on the ground?

The preferred method of dealing with engine fires is similar to that of fire protection for buildings; take steps to prevent them, and provide methods for putting them out should they start. We don't go blowing up buildings that are on fire just because it might be quicker than putting it out.

So instead manufacturers are required to provide many features to prevent fires. Areas around the engines are separated into zones by firewalls and seals, required to prevent spread of fire. Any flammable fluid is required to be contained and drained, and separated from ignition sources.

If a fire does start, the engines have fire suppression systems installed. The system has to be tested to show that it provides the required suppression to a fire, and the aircraft generally carries enough suppressing agent for at least 2 uses. Even if this doesn't work, the isolation features built in should prevent the fire from spreading, and possibly allow it to burn itself out of fuel or oxygen. In most cases an aircraft is close enough to an airport to land before this becomes an issue.

These measures have been shown to be adequate. When was the last time someone died because of an engine fire on an airplane? Fires are extremely rare, and fires that can't be dealt with by the existing measures are even more rare.

There are many more reasons why dropping engines is a bad idea.

Some designs allow an engine to shear away from the wing in the event of a crash, but this is not designed to work in flight. Aircraft that drop items like weapons in flight require extensive design and testing to make sure that the object will drop away from the aircraft properly. An aircraft in an emergency like an engine fire could be making extreme maneuvers that would make this even more difficult.

Objects like weapons that are designed to be dropped regularly still malfunction. How can you make an engine that's been installed for decades separate reliably? If you are relying on this feature for safety, there will be added cost for designing, installing, and maintaining the system. Those costs could be reduced if you don't rely on the feature as much. But then if the current measures are enough, why accept that extra expense?

Investigators generally take interest in engine fires. If you drop the engine, there goes the best evidence for figuring out how the fire started, and what could have prevented or mitigated it. Something large like an engine would be easier to find than smaller parts, but there is still the risk of loss or damage hindering the investigation. If the problem is bad enough that airplanes are dropping engines, it would be better to fix the problem than address the symptoms.

If you constrain pilots to only dropping an engine over water, this complicates things further. There are already rules about where airliners can dump fuel, but dumping fuel is generally a less stressful situation. The pilots chose to stay in the air and dump fuel, so any emergencies are generally less urgent and they have time and attention for where they could dump fuel. If there's an engine fire that requires jettison of an engine, things are going to be more hectic in the cockpit, and it may not be the best time to be considering where this would be allowed, taking things like trajectory into account. And going back to the cost issue, if this would be limited to only areas over water, you couldn't rely on this option to always be available, so is it worth the cost?

Airliners can fly with an engine shut down, but missing an engine is a different matter altogether. The aircraft is required to be tested and certified in many different conditions with an engine shut down. How can we test this with a missing engine? Do we drop an extremely valuable engine every time we test? Do we just make the flight with one engine, which is still in testing itself? Do we not test, and accept that after going to all the trouble of allowing jettison of an engine, the aircraft may not be controllable in some situations?


Short answer: an electronic logbook is legal; the FAA will accept almost anything as an endorsement; it's often most practical to collect endorsements on paper but electronic versions are also fine.
First, the fundamental point about logbook formats is that the FAA defines what you have to log (14 CFR 61.51), but not how you log it. And clearly electronic logbooks are "legal" in the sense that there's no law against using them.
However, I suspect that the main question you're asking is, how can I gather endorsements in an electronic logbook? AC 61-65E is essentially the FAA's practical guide to 14 CFR 61, and Appendix 1 lists recommended sample endorsements, with this comment:

The following examples are recommended sample endorsements for use by
authorized instructors when endorsing logbooks for airmen applying for
a knowledge or practical test, or when certifying accomplishment of
requirements for pilot operating privileges. Each endorsement must be
legible and include the instructor's signature, date of signature,
certificated flight instructor (CFI) or certificated ground instructor
(CGI) certificate number, and certificate expiration date, if
applicable.

So it's clear that you need a "signature" from your instructor and for most people that means paper. But you might start questioning what a "signature" really is and if you can substitute something else. Fortunately the FAA has an entire AC (AC 120-78) on electronic signatures that applies to part 61 and it says:

An electronic signature may be in the following forms.

A digital signature
A digitized image of a paper signature
A typed notation
An electronic code
Any other unique form of individual    identification that can be used as a means of authenticating a    record, record entry, or
document

That's a very broad definition of an electronic signature, although it seems clear that the FAA wants it to be "individual" and non-repudiation is a requirement:

An electronic signature should prevent a signatory from denying that
he or she affixed a signature to a specific record, record entry, or
document

However, there's also the practical question of how you collect endorsements. If you demand that your CFI creates an account in your logbook software, or generates his own digital certificate, or whatever else will make your electronic life easy, he may simply refuse. And how do get his endorsement when you're at that grass strip in the middle of nowhere with no cell signal or WiFi? How do you explain AC 120-78 to a skeptical DPE or FBO owner who's never heard of it before?
In the end, the simplest solution is often to just to get a physical signature on a piece of paper with all the necessary information as per AC 61-65E. If you then want to go digital and shred the paper, you can always scan it and add it to your electronic logbook as per AC 120-78.
But, if you want an electronic endorsement or signature and your CFI is willing to provide it, that's also fine. I use MyFlightbook for logging (no other connection and I'm not endorsing it) and their FAQ addresses whether electronic signatures are valid (links not preserved from the original):

The FAA does accept digital signatures, and outlines the criteria for
doing so in FAA circular AC No: 120-78A. While we believe MyFlightbook
is compliant with this AC (and we explain why we believe MyFlightbook
is compliant here), the FAA has thus far not indicated willingness to
even evaluate, much less certify, online logbook systems for
compliance.

My personal experience so far has been that DPEs have no problem with accepting electronic logbook printouts and endorsements. If something seemed suspicious then I assume they would investigate and ask some questions.


Technically the B-2 bomber has rudders, they are "drag rudders" (or split rudder) and are located on the outer portion of the wing:

Source: Quora
The rudders open in a clamshell configuration to create a drag force on the outer part of the wing. Because these are on the outer part of the wing, they can create a significant yaw force.


How do pilots adjust trim on the B777, where the control forces are simulated?

The basic idea, as the FCOM says, is to simulate control column forces (as in 'conventional' aircraft) so that the pilot knows that he/she is out of trim. So, once the aircraft has been trimmed, there is no force on the control column- the pilot stops trimming at that point.

Boeing 777 uses a feedback actuator to give an artificial feel to the pilot emulating conventional aircraft- this is no accident, as Boeing B-777: Fly-By-Wire Flight Controls notes:

  The philosophy employed during the design of the 777 Primary Flight Control System  maintains a system operation that is consistent with a pilot’s past training and experience. What is  meant by this is that however different the actual system architecture is from previous Boeing airplanes, the presentation to the pilot is that of a conventionally controlled mechanical system.

The control columns (yokes) have feel units, which provides tactile feedback to the pilots just like conventional aircraft:

  A gradient control actuator is attached to the two control column feel units. These units provide the tactile feel of the control column ... (This) is consistent with a pilot’s experience in conventional commercial jet transports.

The image below shows the Boeing 777 yoke with the trim switches.

... The buttons on the right side of the yoke control the trim surfaces for the elevator.; image from wired.com

This trimming system works just like the conventional aircraft- as you noted "they hold the required attitude using the yoke, then trim the aircraft until no force is required to hold the yoke in that position". Note that, though what happens internally is different from the conventional aircraft, what is presented to the pilot is same. From An Analysis of the Boeing 777 Fly-By-Wire System:

  ... the pitch trim system ... is used in the exact same way, that is, should the pilot find himself pushing the control column forward to keep his desired flight condition, pushing the trim "up" ... will gradually reduce the required force on the control. The opposite goes if the pilot is pulling back on the control. Just like in any aircraft, the ship will be "in trim" once the required force on the control column is zero.


Denver International Airport pneumatic tube systems

According to the Public Relations Department at the Denver International Airport, as of May 24, 2019 there is no such pneumatic tube system at the airport.

  Hello Juan,

  Thank you for contacting Denver International Airport. We have
  evaluated your email. I spoke with airport operations to find out if
  they had any information on using a pneumatic tube system and they
  advised me they do not. We do appreciate your feedback.

  Thank you, kindly, for bringing this matter to our attention.

  Warm Regards,

  Flydenver Team  Meseret


What is this equipment under nose of aircraft?

The report says the aircraft was undergoing a landing gear system check. The equipment looks like a trolley-mounted inspection ladder that could well have been used during such a check.


What is the difference between the FAA FNS NOTAM and the FAA PilotWeb NOTAM websites?

I got this response via email from the FAA:

  PilotWeb is considered a Legacy Application based on the USNS, United States NOTAM System. The FNS, Federal NOTAM System, NOTAM Search is a new application. Many Legacy applications will eventually be replaced with the newer FNS applications over the next year. Both applications should be able to provide you with the information you are looking for.