What is the best way to reapply for a denied Class 3 medical certificate?

Take steps and do your homework BEFORE applying for your medical through FAA MedXPress!
I suggest discussing your concerns with a qualified Aviation Medical Examiner or beforehand, assuming you are a member, with AOPA Legal and Medical Services. AOPA has an excellent list of resources on health conditions that may affect certification.
Because a possible history of counseling may qualify as treatment, consider the alcohol and drug abuse guidelines. Note the phrase complete abstinence.

1. To be considered for medical certification, you should write to the FAA, stating that you have completed at least one full year of recovery with evidence of complete abstinence after being treated for drug or alcohol abuse. Although the Part 67 regulations require that there be a sustained period of abstinence of no less than the preceding two years, pilots may be considered for recertification as early as one year after successful treatment with appropriate documentation.
2. The FAA will require the following:
a. Your complete treatment records and discharge summaries.
b. An evaluation conducted by a professional who has had training in diagnosis and/or treatment of addictions. These professionals include substance abuse counselors, psychologists or psychiatrists, other physicians with training in addictive disorders, or members of the American Society of Addiction Medicine (ASAM). (A psychiatric and psychological evaluation may be required if the initial evaluation is inconclusive).
c. Evidence of successful completion of an inpatient or intensive outpatient program with a documented commitment to abstinence.
d. Participation in an acceptable aftercare program consisting of individual and group counseling sessions for at least 12 months.
e. Establishment of a monitoring system that includes a physician with expertise in substance abuse disorders, and
f. Additional monitoring reports from employers, family physicians, or others, as well as alcohol testing when indicated.

The mental health section has a page on ADD/ADHD. Summary excerpt is below.

Because of the potential for significant underlying psychiatric or psychological problems and the side effects of medications, the FAA does not currently allow medical certification for a diagnosis of ADD/ADHD requiring the use of medication.
For medical certification consideration, you will need to have
discontinued all psychoactive medications for at least the preceding
90 days.  After being off the medications for 90 days, a
neuropsychological evaluation should be conducted.  The
neuropsychological evaluation must also include the following three
tests:

Trail Making Test
Wisconsin Card Sorting Test
Paced Auditory Serial Addition Test (PASAT)

If the airman is an adult who has been prescribed one of the
stimulant-type drugs for ADD, but has not been diagnosed with the
disorder, the medications will have to be discontinued for three days
before undergoing the neuropsychological evaluation noted above.

Because you may have a history of treatment with antidepressants due to the past prescription, the mental health section has a page on special issuance for depression with antidepressant usage. Summary excerpt is below with emphasis in the original.

Effective April 5, 2010, the FAA began considering individuals for
special issuance medical certification who are being treated for
depression with one of four specific antidepressant medications.  All
classes of medical certification will be considered, but individuals
who are granted a special-issuance medical certificate under this
policy may take only one type of antidepressant medication limited to
the following four medications: Fluoxetine (Prozac), Sertraline
(Zoloft), Citalopram (Celexa), or Escitalopram (Lexapro). All these
medications are SSRIs, antidepressants that help restore the balance
of serotonin, a naturally occurring chemical substance found in the
brain.
Increasingly accepted and prevalently used, these four antidepressants
may be used safely in appropriate cases with proper oversight and have
fewer side effects than previous generations of antidepressants.
While the focus of this policy statement is on individuals being
treated for depression, the FAA realizes that these four medications
may be used to treat conditions other than depression.  It should be
noted, therefore, that, in all instances, the FAA will continue to
consider applicants and make determinations on a case-by-case basis
under the special-issuance process just as it always has.
…
No regulatory changes are being made under this policy.  Further, the
FAA continues to believe that applicants requiring use of multiple
antidepressant medications or use of any other psychotropic medication
in conjunction with any one of the four specified in this policy will
not meet the criteria set forth under this policy.  The use of
psychotropic medication continues to be disqualifying under the
medical standards and special-issuance certification will be granted
only after thorough analysis of each individual case presented and
only when appropriate conditions and limitations are in place so that
the applicant may safely be permitted to operate an aircraft.  It
should be noted that as new information becomes available and
recommendations from the medical community change it may be necessary
for the FAA to again revise its policy.


What is the history of the CFI spin endorsement requirement?

I can't find a definitive answer but it looks likely - but not certain - that endorsements were introduced sometime between 1980 and 1991.
An AOPA article says that spins became an instructor-only thing in 1949, per CAR Amendment 20-3 (which I can't find online). That doesn't say anything about when an endorsement was introduced, though.
AC 61-67C - Stall and Spin Awareness Training has some historical information on page ii, including this (emphasis mine):

In January 1980, the Federal Aviation Administration (FAA) announced
its policy of incorporating the use of certain distractions during the
performance of flight test maneuvers. This policy came about as a
result of Report No. FAA-RD-77-26, General Aviation Pilot Stall
Awareness Study, which revealed that stall/spin related accidents
accounted for approximately one-quarter of all fatal general aviation
accidents. National Transportation Safety Board (NTSB) statistics
indicate that most stall/spin accidents result when a pilot is
distracted momentarily from the primary task of flying the aircraft.
Changes to part 61, completed in 1991, included increased stall and
spin awareness training for recreational, private, and commercial
Pilot Certificate applicants. The training is intended to emphasize
recognition of situations that could lead to an inadvertent stall
and/or spin by using realistic distractions such as those suggested in
Report No. FAA-RD-77-26 and incorporated into the performance of
flight test maneuvers. Although the training is intended to emphasize
stall and spin awareness and recovery techniques for all pilots, only
flight instructor-airplane and flight instructor-glider candidates are
required to demonstrate instructional proficiency in spin entry,
spins, and spin recovery techniques as a requirement for
certification. Part 61 was extensively updated in 1997.

In version A of the Flight Instructor PTS (May 1991), candidates are required to demonstrate a spin but the examiner can accept an endorsement instead, at their discretion (pp. 2-xliii - 2-xliv):

At the discretion of the examiner, a logbook record attesting
applicant instructional competency in spin entries, spins, and spin
recoveries may be accepted in lieu of this TASK.

The task itself is described as:

Demonstrates and simultaneously explains a spin (one turn) from an
instructional standpoint.

So we can say for sure that since 1991 at least, instructor candidates have been required to either spin the aircraft during their checkride or have an endorsement saying they were capable of doing it. (I say "since 1991" because the same wording is still in the CFI PTS today.)
Of course, getting the endorsement requires spinning anyway (see AC 61-67 again), meaning that the candidate always had to spin an aircraft in order to qualify. The endorsement wasn't a way to avoid doing that.
I can't find any earlier sources or PTS versions that show the pre-1991 requirements, maybe someone else will have more luck.
And to answer your second question, 1991 was 'only' 29 years ago. It seems very possible that there are instructors who have been active for longer than that. If you're wondering if some instructors out there may never have spun an aircraft, the AOPA article implies that they've 'always' been required to spin aircraft anyway, regardless of exactly when the endorsement became an alternative to doing it in the flight test.


Do propellers generate static electricity in flight and how is that handled?

While these might not be specifically for static from the prop, static dischargers help bleed charge away from the aircraft. Static definitely does build up on an airframe, requiring grounding (electrically) your plane before fueling.


Does the stream of engine thrust act as a good drag shield against the nacelle?

The nacelle is not some solid block. For the flow it looks like a hollow, slightly blocked tube.

The flow ahead of the nacelle is indeed slowed down in flight, but only a little, entering the intake face at a flow speed of around Mach 0.4 to 0.5. This compresses the air ahead of the nacelle when flying in cruise at around Mach 0.8, so what enters the intake is already slightly compressed. Note that this compression does not involve boundary layers or shocks, so it is very efficient. The effect of the compression is that some of the air flowing towards the nacelle is pressed aside to flow around it. To avoid flow separation, the intake lip is rounded.

Pre-compression helps, because it raises the pressure in the whole engine and increases its thrust. What might be looked at as drag is in fact increasing the thrust of the engine! Of course, by further compressing and heating the ingested air the engine accelerates it, so the outflow speed of the core flow is easily double its entry speed. The outflow fills up the cross section of the engine, so the outer flow never has to flow into a void and experience separation (which is responsible for most of the drag of blunt bodies). Instead, it meets a faster jet of air once it has passed the engine fairing and is accelerated during the mixing process.

Only if the engine is idling or off will the nacelle cause real drag.


Are there any runways that aren't labeled reciprocally to each other?

Elk City, ID has runway 14/35 with about 30 degrees between reciprocal approach paths:


Is it safe and effective to have "glider pilot mentality" when landing single-engine fixed-wing aircraft?

Diamond aircraft are very low drag and do not have particularly effective flaps, so sideslipping is certainly an effective way to approach the problem. However there are considerations you need to be aware of:

A steeper approach can bring you down on top of another airplane on final approach. Maintaining a more common approach angle is safer as it is less likely to bring you into a potential collision, and keeps you on a path where other pilots are likely to see you
Steep sideslips are not particularly comfortable for passengers, the steep angle and different feel can be frightening
Having your engine idle for long periods can lead to ice buildup in your carburetor, even with the heat on. It also lets your engine cool down quite a bit. Keeping some revs on keeps things warm up front
A steep approach angle makes it harder to round out accurately
A mishandled sideslip can lead to a loss of control. If the ball is to one side and you get past the critical AoA you will be executing a snap roll at low altitude, which = bad

There's nothing wrong with using sideslip and keeping up with the technique - it's very useful if you catch a thermal on approach, are given a slam dunk approach, or need to get on the ground fast. For me it's not the best tool for normal approaches when you have alternatives, especially if you come in at a very steep approach angle.

One technique I've heard of for approaches on Diamond single engine airplanes is to use a combination of both: a slight sideslip dirties up the airflow enough to create some useful drag, and power is used to maintain the approach angle.

I can't think of a light airplane you can't sideslip, or any airplane you can't sideslip for that matter (perhaps the Mig 15). Sideslipping was used successfully in the Gimli Glider incident, and that was a 767! There are limitations which will be listed in the aircraft documentation, for instance you should not sideslip a C152 above 20 degrees of flap. If I'm flying a C150/152/170/172 I follow that rule.


How frequent are TCAS resolution events?

I found a very interesting paper from 2007 that analyzed TCAS performance. They analyzed recorded data to come up with 1 RA per 116 flight hours.

  Over this time period, monitoring took place for approximately 190
  days, and roughly 200,000 Mode S flight hours were observed within the
  sensor’s 60 nmi coverage area. We observed a total of 1725 RA events,
  corresponding to an average of 9 RAs per day, or approximately one RA
  every 116 flight hours.

They explain that the data was taken in the Boston area, so the high amount of traffic contributes to the high number of RAs.

This thread on Airliners.net suggest differently, at least in the sense that for those pilots it is a matter of a few over years, depending on where they typically fly.


How can you fly at 0kts without stalling?

No, stalls can occur at any airspeed, attitude, or load factor.  All that is needed is to exceed the critical angle of attack and you have stalled the airplane.

Some places this can occur and does happen if mishandled by the pilot is at the top of inside loops, where the airplane can come very close to a zero airspeed if it's done wrong.  Another place this does occur is a hammerhead stall where the stall occurs in the vertical, just as the aircraft is at or comes very close to zero airspeed.


Depending on what country you live in, yes, but it will cost you.

It's probably the cheapest to fly an airplane you own in the United States.  Here, the answer is yes, with very little restriction, you can just drive out to the airport and fly an aircraft within the National Airspace System.  You just must abide by the legal and medical requirements for you, and the legal and operational limitations of the aircraft.  Most airports throughout the country are uncontrolled, so you may have limited, if any, interactions with ATC.  The ability to fly pretty much anywhere you like with very few restrictions is what makes GA so appealing in the United States.


What kind of airspeed does a (3D) GPS measure?

Q: "What kind of airspeed does a GPS measure?"
A: "None whatsoever."


Descending on a given glide slope (e.g. ILS) at a given airspeed-- is the size of the lift vector different in headwind versus tailwind?

EDIT: This question is really not about lift vectors. It is asking about the total amount or total value of lift needed with varying headwinds.

Everyone seems to be over complicating this very basic question which asks about two identical aircraft flying down an identical ILS glideslope with the exact same indicated airspeed. The only difference is the amount of headwind.

It is so simple. Rate of descent is a direct result of the amount of lift being produced.

It is a FACT that the aircraft with less headwind will need to produce LESS lift than the aircraft with more headwind, in order to maintain the same indicated airspeed, and follow the glide path.

The rate of descent with a headwind could be -500ft/min while the aircraft with a tailwind could be -1000ft/min.

The aircraft maintaining a -1000ft/min descent because of a tailwind will need to produce LESS lift than an aircraft maintaining a -500ft/min with a headwind.


Can I use parachute fabric to cover an aircraft fuselage and wings?

Is there an experimental aircraft association in your country? I would advise you to get into contact with them for better advice.

If you want to know whether this fabric is good enough for covering your airplane, you should plan to perform a load test on the finished airplane. For this you need to know which loads the structure will have to endure. That would be about three or four times the weight of the aircraft on the wings and a proportional amount of load on the tail surfaces. Also consider asymmetrical loading conditions - the photo implies you want to cover a fuselage, and there torsional loads will probably produce the highest stresses.

Another consideration are dynamic and aeroelastic loads. Here it is not only the absolute tensile or compressive strength that counts, but also the stiffness of your structure. The material has an influence, but the way you build the airframe is even more important (think fiber direction - fabric has different properties in different directions). Therefore, I cannot give a good answer without more details.

Lastly, how you finish the fabric will have a lot of influence how long the material will endure in real life. Do you intend to use dope? At least plan to add UV protection coating on top.


A cycle is a start to a shutdown.  Lets say there is a flight that is loaded with pax, bags, and fuel.  They push back and start both engines since the weather is good and their at an outstation.  As they taxi to the departure runway, BAM, ground calls up saying there is a groundstop for the hub and its going to be about 30 minutes.  The flight pulls into some empty ramps space, and shuts down both engines.  Groundstop lifts, both engines started again, and the flight departs.  After landing, pulling into the gate, and shutting down the engines, we can say that for this flight, each engine went through two cycles.  ALL of this info is logged and maintenance can access it.  With some of the newer engines and higher service packages, OEM


Do pilots have to consider unplanned delays for Part 135 duty time exceedance?

Note that if you operate under §135.267(b), that there isn't any specific duty time definition -- there are only regulations concerning the maximum flight time and minimum rest time in §135.267(d) (see this question for the definition of rest time). In a FAA Civil Penalty Order, it is noted that duty time is:

  any time that is not a rest period.

If you're operating under §135.267(c), "a regularly assigned duty period" is also not defined, however, a legal interpretation in 2009 states that:

  a pilot under a regularly assigned duty period "comes to work and ... goes home at the same time every day".

Now the question is, whether late passengers or being held up by ATC would be considered as affecting "the planned completion time of the assignment". The FAA has held in prior legal interpretations that:

  delays caused by late passenger or cargo arrivals, maintenance
  difficulties, and adverse weather are beyond the control of the
  certificate holder.

And in another legal interpretation:

  delays due to air traffic control, mechanical problems, or adverse
  weather could constitute circumstances that are beyond the control of
  the certificate holder.

However, it is noted that these provisions only apply if the original schedule was realistic. For example, if it is typical that ATC will place aircraft into a hold for 1 hour and this is not taken into account, this could be considered an "unrealistic" schedule for the purposes of §135.267.

Note that if no initial "planned completion time of the assignment" was calculated prior to accepting an assignment though, then "being late" may not be a legal defence if taken to court. In 1995, a case involving Charter Airlines, Walker and Mort questioned whether it was a violation of §135.267(b) & §135.267(d) to accept a flight even when it was known that the cargo would be late to arrive.

Because it was found that there was no "planned completion time of the assignment", they were on duty when waiting for the cargo (and therefore not "free of all obligations") and they had accepted the assignment after it was aware that the incoming cargo would be late, the FAA issued civil penalties amounting to \$10000 for Charter Airlines, and \$2000 each for Walker and Mort.


Is this explanation of adverse yaw correct?

First of all, in the diagram they show the force on each wing being the same.

In a steady roll, i.e. when the roll rate is constant, the forces are the same. A non-zero moment causes angular acceleration, so when the aircraft is rolling with constant rate of roll, the moment must be zero, which means the lift on both wings have to be equal.

That rules out difference in magnitude of lift as the source of the difference and leaves the difference in angle as the only plausible explanation. The explanation is correct.

When you first deflect ailerons, the wing with aileron down does indeed start to produce more lift and the wing with aileron up less lift. This difference causes rolling moment, which causes the roll rate to increase. It already starts causing adverse yaw due to the difference in magnitude of lift too.

However as the roll rate builds up, the angle of attack increases lift on the wing going down and decreases it on the wing going up until the lift equalizes and the roll rate stabilizes. At that point the lift is the same and the adverse yaw is caused by different direction of lift due to different angle of attack.

The fact that ailerons are deflected throughout the roll might lead you to think that there is still difference in lift. But there isn't. The aileron deflection just changes the roll rate in which the forces are in equilibrium.

Also while the angle between realtive wing and the total aerodynamic force (which corresponds to the relation between lift and induced drag) is in general not constant, in this case all the factors it depends on — wing span, air speed and density — are (almost) the same for both wings, so the difference in angle of attack is the main factor for the direction of the resulting force.

And last, but not least: How It Flies is very reliable regarding the physics (and most other things too). I would be very surprised to find an incorrect explanation there.


What role, if any, does visual aesthetics play in the design of modern airliners?

A friend of mine, who did the design of the Gulfstream G650 canopy, designed the cockpit windows on that jet after the lines of an Aston Martin sports car.  I suspect there are a few other features like that in various aircraft.

That being said, despite the aircraft design mantra of 'if it looks good it will fly good' most the the design choices made in aircraft is very utilitarian.  Aerospace engineers - and in particular the management at the major OEMs - are some of the most boring, unimaginative SOBs you will ever meet.  They generally leave creativity to the marketing departments and make every effort to pound flat any nail that sticks out.

The only exception to that rule that I can think of was Burt Rutan of Scaled Composites, who when his own way and designed unique planes as virtual works of art - but also were highly functional with great performance and capabilities.  From the Vari-EZ to Spaceship One, that guy is in a league of his own.


What's holding equipment manufacturers from going into multicore, RTOS-based equipment?

Development costs, complexity and need.

On a system that has to be hard real time multi-core is a pain(think expensive) and most things that need to be hard real time are not that complex. Things that don't need to be hard real time don't need to be RTOS, so you have one system that handles all the hard real time stuff and one that runs Linux and handles the other stuff.


What were DJI drones spying on? What data did they capture?

I doubt anything was gleaned per se, but there was recognized a significant security risk here and the military discontinued the use of the produce for fear of integral malware which could give an unfriendly foreign power a readily available means to spy on other nations.

If you have large numbers of these drones in operation all over the United States and other nations of interest equipped with a GPS receiver, and they make use of a controller linked to a smartphone or other device with internet access, you now effectively have an unwitting air force of spy aircraft operating within your target's airspace where the information transmitted from the drone is readily accessible to intelligence agencies within China.  It probably cannot gather sensitive national security information, but these kinds of drones could be used to uncover non-classified government or military activities which could be of use to Chinese data analysts.  We use to do this on a regular basis using spy satellites over Russia and Eastern Europe and thinking several levels ahead, considering how interference with more mundane activities could have a real impact on.

Analysts in China can glean through users until they find ones doing something of interest.  People operating drones near military installations and ranges, etc can be useful and their video can be analyzed e.g. a kid in Las Vegas who lived near Nellis AFB may have his drone targeted when he/she flies it.  If the video captures images of the airbase, analysts can look at day to day differences for things like base maintenance, vehicles in the motorpool, movement of aircraft on the flightline, etc. and the data could be used to predict patterns of behavior, operations protocol, etc. that can be useful to military intelligence.  It's no wonder the US military stopped using DJI products for that reason.


What options do the crew have when passengers go berzerk?

See Chapter 4 of this IATA document for flight crew management of unruly passengers.

http://www.iata.org/whatwedo/safety/Documents/Guidance-On-Unruly-Passenger-Prevention-And-Management-1st-Edition.pdf

In general, they will weed a lot of the negative behavior out on the ground prior to boarding by looking for signs of agitation or aggressiveness towards other passengers or crew.  Should a passenger becom unruly while enroute, the following is generally done.

Assess the situation and level threat:  what's happening? who is doing it? what are their grievances? Are the legitimate e.g. A family member having a medical emergency or trivial e.g. Passenger in 22B is drunk and aggressive?

If there are other than legitimate reasons for the disruption, action in taken using the use-of-force continuum:

Physical presence - flight crew will be nearby watching subject.

Verbal commands - confront subject.  Inform them of both the airline's and Law Enforcemnt's zero tolerance policy toward their exhibited behavior.  Inform them if they continue with this behavior the aircraft will be landed, they will be placed under arrest by LE on the ground, and that penalties for their actions are severe.  Try to calm them down as well, but do NOT serve them alcohol, even if requested.

If behavior continues, quietly inform the cockpit crew of the disruption and they will make arrangements to divert to nearby airport and inform local airport police and other LE agencies to be ready on the ground.

If passenger has become so unruly that they are posing an immediate threat to other passengers around them, physical force can be used to restrain them by the flight crew.  This poses a high risk and should only be done as a last resort to regain control of the cabin.  If there is a federal Sky Marshall(s) on board they can assist the crew here as well.

Restraints such as handcuffs and the waist belts may be used to immobilize subject until LE can take over.  Divert will become urgent.

Electro Muscular Disruptors - flight crews are now being equipped with and trained on the use of the TASER EMD systems to immobilize unruly passengers in order to restrain them.

If subject's actions pose an immediate threat to life and limb of passengers and threaten the safety of the aircraft and crew (VERY low probability but it is is a contingency), deadly force may be used to neutralize the threat.  Near as I know some Capt./FOs do carry firearms as do Sky Marshals.  I'm not aware of guns being issued to flight attendants.


How would one calculate the thrust-to-weight ratio for a minimum turn radius?

You can't. Turn radius is a function of true airspeed & bank angle, and nothing else. A J-3 Cub flying at 40 knots will have a pretty tight turn radius compared to an F-16 with its 9-G turn at 100+ knots, just because the Viper can't approach the Cub's low speed. Or take a KC-135R -- better T/W than a T-38, but not really a low-speed performer nor a high-G machine.

Turn radius in isolation will favor low-speed aircraft over high-speed aircraft, even when the latter have better T:W ratios.


Using 747-100/200 aircraft at the two 747 carriers I flew for in the 1990s as an example, the specific uses (not in any particular order) were:

pneumatic power to start the engines
pneumatic power to run the air conditioning packs when the engines were not running.
electrical power on the ground, available regardless of whether the engines were running or not. Many aircraft can use APU electrical power inflight, 747-100/200s do not.
hydraulic power on the ground when the engines were not running via the pneumatic duct. I can't remember whether that could be done inflight.

Assuming that electrial and air was not available from a ground cart, the APU on a cold airplane would be turned on when the airplane was opened up and turned off after the engines were going.

Prior to landing, the APU would usually be turned on a few minutes before landing. It would be left on until a ground cart (if any) was hooked up or until the aircraft was vacated and closed up.

Other aircraft types and operators employ their own procedures, and their APU uses may differ.


First let's clear up some things:

A SCRAM jet is a Supersonic Combustion RAm Jet, where the flow speed in the combustion area is still supersonic. Efficient combustion needs low speeds, hence a supersonic combustion is not a good solution to maximize efficiency. It needs rapidly mixing and burning fuels like hydrogen, lest most of the thermal energy release happens when the gasses have left the engine.
The operating principle of all aircraft engines with continuous combustion is that the kinetic energy of the flow is converted into potential energy, namely pressure. This pressure is needed to convince the hot combustion products to leave the engine at the rear end, where the pressure drops as the flow is accelerated again. If the engine flies at subsonic speed, the first area where supersonic flow is possible is in the convergent-divergent nozzle. Normally, pressure recovery is too small at subsonic speed, and either some turbo machinery or an oscillating pressure wave is needed to increase compression.

A de Laval nozzle (first developed by Ernst Körting in 1878) is a fixed convergent-divergent nozzle and needs high inlet pressure to function. Placing it at the subsonic inlet would require a near vacuum at the outlet to make it work. Using it in combination with a Ram jet would result in separated, subsonic flow with little pressure recovery in the combustion area, and very little thrust could be produced. In principle such an engine would run, but I doubt that it will even produce enough thrust to result in a net thrust gain. Efficiency would most likely be negative.


Is navigation around thunderheads done at the pilot's discretion?

If you are in controlled airspace its very possible ATC will direct you around weather, you can find out more about that in this question.

However what ATC can see on their scope varies from place to place and weather moves quickly. As such pilots can, and often do request deviation for weather. Lets say you are flying along dodging some clouds here and there, popping in and out, and all of a sudden you pop out with a cell forming in front of you. You may request something like:

  N123AB requesting left turn 20 degrees for weather

  N123AB left 20 approved for weather avoidance

It may also not be a bad idea to file a PIREP to help others out.

Ultimately as pilot in command you can deviate from any rule to ensure a safe flight. If you were about to fly straight through a storm and ATC was not allowing a deviation or not issuing one a case could be made for deviating any way. You can read more about that here.


A turbine is a machine that extracts energy from a moving fluid and converts it into work. In the turbine blades, the air is expanded, which produces work. In many ways, the turbines are the opposite of compressors.

"Two stage reaction turbine" by S.M.Yahya - Turbomachinery. Licensed under Public Domain via Commons.

The turbines used in the aircrafts are axial flow turbines, which employ multiple stages to extract work from the air coming out of combustion chamber.

The turbines have two parts- the stationary nozzles (or stators) and  the moving rotors. The purpose of the nozzles is to turn the incoming flow so that that it impinges on the rotors at the correct angle, while the actual work is extracted out from fluid by the rotors.

"Velocity triangle for an axial turbine stage" by S.M.Yahya - Turbomachinery. Licensed under Public Domain via Commons.

Basically, the rotors are 'turned' by the incoming fluid as shown above which produces work to rotate the shaft (which runs the compressor). In case of turbojet engines (and to some extent turbofan), the air pressure decreases, while the velocity increases. This provides the required thrust.

The main mechanism by which the turbine blades spin is that the flow turns the rotor blades by hitting them, rather than any lift being produced.


Could the Space Shuttle take off like an airplane?

Despite the scene in Moonraker the Shuttle orbiter carried no fuel for the main engines.

Further, the orbiter sat nose down on its landing gear, lacked the elevator authority to raise the nose off the ground at landing speed, and could not retract its landing gear (it used a straight-fall gravity deployment).  The OMS didn't have enough thrust or delta-V at sea level to accelerate the orbiter from a stop to flight speed, even without the pitch authority issue.


What is the difference between an engine "shut down", "cut-off" and "cut down"?

To be specific:

Shutdown: To take a step or series a steps to stop the operation of a machine and put it into its normal inoperative state. A shut-down procedure may include cutting off fuel, closing valves, and turning off pumps, or may just be flipping a switch to OFF.

Cut-off: To interrupt (or a noun describing something that interrupts) the supply of something to a machine; fuel, water, electricity.  Generally refers to closing of a valve or opening an electrical contactor or switch.  On a piston engine, you have a mixture setting called "idle cut-off" that blocks flow of fuel at the carburetor. You might see a switch that opens a contactor to an electrical bus, for use in emergencies, labelled "Bus XXXX Cutoff".

Cut-down: I've been working in aviation in N America since 1975 and have never heard of this term as relating to operation of an engine (maybe in UK?).  Normally if I see the word cut-down it's an adjective that describes something that has been physically altered to make it shorter or smaller.  Like a cut-down vertical fin, or a cut-down antenna, or cut-down propeller blades.  I'd be surprised if anybody on here has ever heard of the phrase "cut down power" as an instruction to reduce power, or thrust.  You just say "reduce".

You DO sometimes hear the word "Cut" by itself as an instruction to go to idle or to remove power completely on an engine.  A skydiving pilot may get an instruction to "Cut" when it's time for jumpers to exit.  Some day when you are on a jet type course, one of the simulator sessions will include "V1 Cuts", where one engine is failed just as you are passing V1 (whereupon hilarity ensues the first time you do it).  So in those cases, power is cut, but not "cut-down".


Does transport-type certification account for engine separation and its possible effect on hydraulic lines?

Unsure whether it is designed to withstand an engine separation, but Boeing 737 seems to have an engine separation memory items:
https://www.johanpercherin.info/airline-pilot-training/boeing-737-memory-items-engine-fire-severe-damage-or-separation/
And 777 has one as well:
https://www.theairlinepilots.com/forumarchive/b777/b777memoryitemsandlimitations.php


Is it legal to give flight instruction in my own airplane without 100 hour inspection if doing it for no charge?

I agree with acpilot that if you're merely renting the plane to this pilot then no 100hr is required. Rentals are not "for hire" operations.

I do that with a Cherokee that I rent out. I don’t provide the CFI and I do not fly it for others. Several students have taken their practical tests in the plane and I made sure they could explain the FAR to the DPE and they had no problems.

As several commenters have stated, it gets tricky when you own the plane and provide instruction. The FAA considers lots of things as compensation that you and I would not. Goodwill, logging flight time, paying for gas, or even paying for lunch or a beer.

I found a clarification letter from the FAA at Aviation Banter.
http://www.aviationbanter.com/showthread.php?t=11563&page=2

May 3, 1984
Mr. Perry Rackers
Jefferson City Flying Service

Dear Mr. Rackers
This is in reply to your request of May 1, 1984, that we render an opinion regarding the applicability
of the 100-hour inspections requirement of Section 91.169(b) of the Federal Aviation Regulations to rental aircraft.
Section 91.169(b) of the Federal Aviation Regulations provides that, except as noted in Section 91.169(c),
a person may not operate an aircraft carrying any person, other than a crewmember, for hire, and may
not give flight instruction for hire in an aircraft which that person provides unless, within the previous 100
hours of time in service, the aircraft has received either an annual or a 100-hour inspection.
If a person merely leases or rents an aircraft to another person and does not provide the pilot, that
aircraft is not required by Section 91.169(b) of the Federal Aviation Regulations to have a 100-hour i
nspection. As noted above, the 100-hour inspection is required only when the aircraft is carrying a
person for hire, or when a person is providing flight instruction for hire, in their own aircraft.
If there are any questions, please advise us.

Sincerely,
/s/
Joseph T. Brennan
Associate Regional Counsel

One correction to acpilot about the 100 hours. Once you start renting for hire, you need to do an inspection every 100 hours. The clock doesn’t restart every time you do the inspection or annual. You are allowed a little leeway to ferry the plane to the inspector, but you don’t reset the clock.
The 100-hour limitation may be exceeded by not more than 10 hours while en route to reach a place where the inspection can be done. The excess time used to reach a place where the inspection can be done must be included in computing the next 100 hours of time in service.


What is this intake at the back of a 737?

The APU insulation panels are not easily damaged, however, it the panels are punctured, you should repair the damaged panel as soon as possible. If you do not repair a puncture immediately, the panel can store fluids in the insulation. If fluids get into the insulation material, you must replace the panel. The air inlet scoop replaces the foam and support insulation (egg crate) that were installed between the APU insulation panels and the bulkhead. During an airplane operation, the air inlet scoop supplies forced outside air through the empty space between the APU insulation panels and the bulkhead for ventilation and for the removal of flammable or unwanted fluids. The location of the air inlet coop is behind the forward insulation panel and adjacent to the forward right side of the APU cowl door.

Source: Boeing training manual


What does a blue light by the toilet sign mean?

You don't indicate which aircraft make and model you were flying in. I'm going to answer with some general information regarding Airbus aircraft, since that's the predominant manufacturer of aircraft currently in SwissAir's fleet. There may be subtleties from version to version.

Short answer: a blue light typically indicates a passenger has pressed the "call attendant" button above their seat. It's used to provide a central indication that assistance is required, and may help localise the row the passenger is seated in by only illuminating a blue light in some parts of the aircraft in closest proximity to the relevant row.

Longer answer

The panel with coloured lights to which you refer is the Area Call Panel (ACP). These panels are situated at either end of the cabin, and possibly in the mid cabin or at other locations depending on aircraft type and age.

The ACP typically has multiple colour indications, such as pink, blue, amber and green. Their meaning is as follows:

Pink: communication from cockpit. Normally steady, flashing if an emergency call is taking place (initiated in either direction: cockpit to cabin or cabin to cockpit).
Blue, steady: passenger call using at-seat attendant button in the passenger service unit (PSU -- overhead panel above each seat row). This light may only appear on particular ACPs, which enables the calls to be segregated by cabin and further by seat location.
Amber: assistance request from the lavatory. Steady indicates a passenger in the lavatory has requested assistance from an attendant. Flashing indicates a smoke detector activation.
Green: attendant call, using the cabin interphone to call between interphone stations.

The indication panel is integrated with, and receives event indications from, the Cabin Intercommunication Data System (CIDS). The CIDS is a crucial network on the aircraft responsible for handling crew communications, managing some aspects of the flight attendant displays, operating the speaker system and giving the relevant indications. Calls requiring attention from a flight attendant typically trigger a notification on the attendant loudspeakers and illuminate the relevant light on the ACP (unless already illuminated) in order to draw attention.

Furthermore, for passenger calls, the relevant seat number light in the PSU is illuminated when the attendant button is operated. This allows the request to be localised to the relevant row and side of the aircraft. If an aircraft door is open, the row number flashes -- typically a door open event leads to the PSU row indications to be illuminated to enable embarking passengers to find their seats more easily.

References

Only a small amount of information is publicly available about the ACP, its role in the CIDS and the CIDS more generally. The information here is corroborated by two sources:

A Lufthansa training manual for the A319/320/321 aircraft, published online. See pages 166, et seq.
Jonathan Hurst's site, in particular the excerpts of A320 technical operations manuals, chapter 10 "Cabin".

Any further sources or references, especially for non-A319/A32x models, are gratefully received in the comments.


Why was I getting an uncomfortable feeling in an R22 at 3,000 feet?

Typical height for helicopters is 500-1,500 AGL, and almost all flights are conducted in this regime.

Below 1,500 AGL the surface is quite close and the ground moves by fairly quickly, so you have a good point of reference.

At 3,000 AGL, you can feel quite disconnected from the earth and can have a bout of altitude fear.

When I had to circle up above out of a valley airport in an airplane, with minimum VFR visibility due to smoke, I felt like I had to keep cross-checking my instruments to maintain airspeed and bank angle. It was an uncomfortable feeling, even having had lots of hood time and actual IMC. So its not unusual for unusual flight regimes to have an unsettling effect.

The circling could have also cause some disorientation.

The most important thing, which you accomplished, is recognizing the signs, not panicking, and you kept flying.


Does the Boeing B787 have safety issues with its battery and windshield?

The 787 is among the safest airliners currently flying. At the time of writing, it has been involved in zero hull loss incidents and there have been zero fatalities due to incidents.

While you can find numerous incidents including those you mention there have been exactly zero total losses and no loss of life on board (due to the aircraft itself - its possible people may have perished on board due to other factors not involved in aircraft safety).

It should be noted that A boeing report on this subject points out (page 19) that most of the aircraft which have had zero hull losses have also not accumulated 1 million departures. Therefore it might be too early to tell if there is any fundamental safety issues with these types. However, there has been 50+ years of learning about safety with regard to aircraft operations - and all of that feeds in to these modern aircraft.

All in, I would consider flying on the B787 to be objectively safe (or, at very least equally so as other similar airliners). Does there exist some "wrinkles" to be ironed out? Perhaps - but they do not affect the overall safety of this type.


Why does turbofan exhaust appear to reverse direction?

What you are describing is a characteristic of fluid dynamics known as eddies. As different portions of the fluid flow faster than others, the friction and surface adhesion between the two layers cause swirling of the fluid and reversal of the current, creating a turbulent flow region. It is this same principle that holds a ping pong ball stationary in a moving column of air.
For a simple overview, you can check out this wikipedia page:
https://en.wikipedia.org/wiki/Eddy_(fluid_dynamics)
For a more scholarly exposition, try this:
https://arc.aiaa.org/doi/abs/10.2514/2.1794?journalCode=aiaaj


Am I expected to stay on glide slope for landing in a light aircraft?

It is more important that your approach is stabilized and safe than you are strictly on slope (i.e. two red/two white). But let's discuss a few things before extending this answer.
ATC is not terribly concerned with where exactly you touch down (especially in a light aircraft) so long as you don't run off the end of the runway. When cleared to land the whole length of the runway is yours to work with:

If receiving “cleared to land” instructions from ATC, you are
authorized to use the entire landing length of the runway and should
disregard any LAHSO holding position markings located on the runway.
If you receive and accept LAHSO instructions, you must stop short of
the intersecting runway prior to the LAHSO signs and markings.

Different runways will call for different touchdown situations which is why it's important in preflight to understand what your landing distance and roll out will be.
In any aircraft you fly you should be proficient (or learning to be proficient) in various landing techniques than includes standard approaches as well as no flap approaches and short field landing maneuvers. If you have all these things in your toolkit you will be fine. If you are proficient in an aircraft you should be able to put it down on the numbers or the 1000 foot markers or any other spot your instructor asks you to demonstrate so long as there is sufficient distance to roll out and stop. You should focus on being able to deliberately put the aircraft down on a spot of your choosing rather than thinking of it in terms of "i always end up touching down on the mid point of the runway" as the latter statement means a very different thing on a 2000 ft runway than it does on a 10,000ft runway. This can generally be controlled with small pitch and power changes on final.
Generally speaking you should fly the glide path if it is available to you as this will guarantee obstacle clearance and keep you safe. While it is never bad to be a bit above glide path (three white, one red) it can be problematic to be very high (all white). The issue with 4 white lights on a PAPI is there is no further indication of how far above glide path you actually are. Making the assumption that you are anywhere near the glide path if you see 4 white lights is dangerous and can lead to a fast, unstable, slam dunk approach. Slope adjustments can be a bit delayed on approach and a power increase will generally bring you back up to slope if you are low while chopping the power will bring you down to slope but remember it will take some time to settle in so you need to think ahead of the airplane.
If you put it all together you will see that staying on slope brings you down to the 1000 'footers, keeps you clear of obstacles, and allows you to make small final adjustments to control your touch down if you want to land a bit short or a bit long.
It is not a question of focusing on one OR the other but focusing on both and realizing how they play together. If you come in on slope you can make small power changes to adjust your aiming point and suit your desired maneuver.
The FAA's Approach And Landing Chapter of the Airplane Flying Handbook has lots of good info on the matter and is worth the read.

Stabilized Approach Concept
A stabilized approach is one in which the pilot establishes and maintains a constant angle glide path
towards a predetermined point on the landing runway. It is based on
the pilot’s judgment of certain visual clues and depends on the
maintenance of a constant final descent airspeed and configuration.
An airplane descending on final approach at a constant rate and
airspeed is traveling in a straight line toward a spot on the ground
ahead. This spot is not the spot on which the airplane touches down
because some float occurs during the round out (flare). [Figure 8-9]
Neither is it the spot toward which the airplane’s nose is pointed
because the airplane is flying at a fairly high AOA, and the component
of lift exerted parallel to the Earth’s surface by the wings tends to
carry the airplane forward horizontally.

To address some points of your directly:

I thought that's what flaps were for - to allow for a steeper approach.

Flaps allow you to fly a steeper decent angle at a given airspeed, this is not a blanket security measure to fly arbitrarily steep approaches at 80Kts in a 172. They also help you to generate more lift at a given airspeed so you can fly a standard approach at a slower than normal speed (think short field landing).

...and approaching exactly on glide
slope usually means I have to add power on short final because I start
getting too low.

If you are on glide slope on short final you are not too low (thats the point of a glide slope). If you are high for most of the approach, cross the slope, then find your self sinking below slope your approach is not stabilized and you are likely coming in hot then cutting power and diving for the runway.

I kinda like being a little higher

While there is no strict regulation on flying above glide slope flying arbitrarily high is typically an indication of an unstable approach that will result in a slam dunk dive final. The glide slope exists for many reasons and should be followed for those reasons.
If you are student pilot (you dont mention here) work on flying stable, on slope approaches. If you already have your ticket I would start some Instrument training and understand what its like to fly the slope in the soup (or foggles) and how being high can be a real issue when you break out, it might help put it all into perspective.


How is maximum rate of climb defined in aircraft specifications?

The "maximum rate of climb" is the highest sustainable ROC for the following conditions...

sea level conditions (or standard atmosphere for other altitudes)
maximum gross or takeoff weight
cruise configuration
maximum rated continuous thrust/power

There are additional minor requirements given in FAR 23 such as the rated power 8 seconds (SFAR to 23, par 6 and 23.63-23.67) after the throttles are moved to the full thrust position but the above is a good generalization.


How does a commercial airliner measure its weight/mass?

Short answer

Determination of mass and balance (or weight and balance) is a critical task for the crew, an error in this operation may have tragic consequences.

Weighing passengers and carry-on items is mandatory per regulation.
Either standard predetermined weights, or actual weights can be used in this operation. Airlines usually use predetermined tables. Tables values take into account different types of travel (e.g. regular and charter).
While the weight must be checked, the center of gravity location is of equal importance. The distribution of the passengers in the aircraft is also taken into consideration.
Aircraft are not weighed prior to each flight, but the basic empty weight must be known and checked periodically per regulation.
Aircraft are weighed simply using scales under the carriages :-)

(source)
The other method is to use jacks. See further below for an image.

So this was the short answer. To understand why and how to balance the aircraft, there are quite a lot elements to introduce. For those interested, just continue!

Weight...

The different elements composing the takeoff weight:

All of these elements must be determined prior to taxi and takeoff.

The mass of these elements are necessary to check that the different maximum weights are not exceeded. However there is another aspect of the masses which needs to be secured: Where are the masses located?

Taking KeithS' example, if there are many heavy people grouped in the forward section, we may have a problem at Vr, even if the MTOW is not exceeded.

... and balance. Location of the center of gravity vs. the MAC

The masses must be distributed so that the center of gravity of the aircraft is located within limits determined relatively to the aerodynamic chord, and the center of lift.

This is required to ensure the stability and the maneuverability, to minimize the efforts on the horizontal and vertical stabilizers and to increase the maximum lift and reduce the drag. On airliners, the center of lift must be located between the CG and the center of lift of the horizontal stabilizer, so that the latter pushes downward to balance the weight.

On airliners the width of the wing is greatest where it meets the fuselage at the wing root and progressively decreases toward the tip. As a consequence, the chord also changes along the span of the wing. The average length of the chord is known as the mean aerodynamic chord (MAC).

The MAC is a portion of the wing, delimited by LeMAC (leading, 0%) and TeMAC (trailing, 100%). The CG must be located in the MAC.

In large aircraft, center of gravity limitations and the actual center of gravity are often expressed in terms of %MAC (on the roll axis, similar limits exist on the two other axis).

(image and text around: Aircraft Design, Mohammad H. Sadraey)

In general, in large transport aircraft, the most forward CG is located as forward as 5% MAC, while the most aft location as aft as 40% MAC. The average CG limits in large transport aircraft are between 20 and 30% MAC.

As commented by Calchas, using wrong weights for the passengers (adults instead of children) may move the CG to a wrong location, not balanced by the trim, and create strong difficulties during the takeoff and the initial climb.

PAX weight applicable procedures

For an airliner, the PAX portion is relatively small compared to the total mass, so the passengers mass is usually estimated based on standard passenger mass tables and the number of PAX per cabin section. Each airline may provide its own standard mass tables, but standard tables are proposed with the applicable regulation:

JAR-OPS1 or EU-OPS1 for Europe (section JAR - OPS 1.620 Mass values for passengers and baggage). Values valid in 2008:

(source)
Those tables have been establish using airlines data obtained by surveys. They are updated from time to time.
In case the operator wants to establish their own equivalent tables, JAR - OPS 1.620 provides a detailed operating mode to sample passengers and weigh them.

For the EU, a new survey was conducted by the European Aviation Safety Agency in 2009 and a proposal for table updates issued:

Passenger and Baggage weight survey

At this point you may want to download the documentation I'm mostly using for this post: Mass and Balance in Aircraft. We are at page 54.

Special cases

There are cases where it is obvious the actual mass and balance will be erroneous if the standard tables are used (this is especially true for a small cabin).

In these cases the operator must improve the evaluation by actual weighing of either all or a sample of passengers and their baggage. The procedure already mentioned for establishing standard tables is used (JAR - OPS 1.620).

Putting all elements together

All masses, arms (distance to the reference center) and moments are finally reported on the aircraft manifest to calculate the correction that must be used for the takeoff (trim amount).

Basic empty weight determination

The aircraft is not weighed for each takeoff, still it has been weighed to determine its basic empty weight and its center of gravity. This operation must be done every 3 or 4 years (9 or 18 years in a large fleet, this is a specific process) according to JAR Ops 1.605, Appendix 1.

Platform scales under the carriages may be used:

(source)

Another method is to use jacks equipped with a transducer at their top:

(source)

Related FAA regulations and JAR-OPS

FAA AC 120-27E and JAR-OPS 1.620 to determine the mass of the baggage, passengers and carry-on items.
FAA AC 120-27E, JAR-OPS 1.607, JAR-OPS 1.615 for the determination of operational items, which include the crew and the crew baggage (there is also a table, that I won't include to prevent comments on the differences with the passenger table -- All tables are based on survey from airlines). The operational items also include catering, emergency equipment, spare parts..

May be interesting too:

There is a confirmed trend of weight increase among the population (including myself). This has an impact on the operational costs. The way airlines manage this impact can be read in a two-part article: The true costs of heavier passengers, part 1, part 2.

Related:

Do some airplanes have weighing scales on the landing gear?
Do airlines weigh passengers and baggage before loading the aircraft?
How much time does it take to calculate the leveling and weighing of big and small aircraft?


Are Cargo Holds Pressurized, Non-pressurized, or vacuumed?

The cargo hold is indeed vacuumed, using a vacuum cleaner, regularly.
It is however NOT drawn vacuum (so having all air removed).
Some cargo holds may be pressurised, some are not. Depends on the aircraft and the requirements of the cargo (life animals want a pressurised cabin of course, just to give one example).


Where can I find sample data required for Engine Condition Monitoring?

Your list of parameters is on the right track, and is the minimum set. If you can add a few more temperatures and pressures at other “stations” within the engine, the diagnostic accuracy improves.
No one on the internet will send you real data. OEMs and operators don’t give out data, because it contains proprietary information. That’s why 90% of the papers you have read probably use simulated data. Also, with simulated data, you actually know what the fault was. With a real engine, you don’t because when you pull an engine apart, there is no simple dimension you can measure to tell you what the change in efficiency of the fan actually is, for example. But, the trick with simulated data is to add a realistic amount of noise.
To generate simulated data you need a gas turbine performance program, like GasTurb or GSP. The latter of these is free for personal use. Maybe if you google “gas turbine performance simulation software” you will be lucky and find something free that does enough for your research.


What produces thrust along the line of flight in a glider?

V is the airspeed. U and w are the horizontal and vertical components of V. The rest of the vectors are forces; W = weight, K = aerodynamic force, L & D are the orthogonal components of K. Those are all the forces involved in a glide.


How does a taildragger steer (taxi) differently to tricycle gear?

It very much depends on the tail-dragger. Many vintage aircraft don't have wheel brakes at all and steer using the rudder, which has the tail wheel or skid attached to it. On these aircraft, steering is ineffective at low speeds, just like when steering a ship with a rudder. Unlike on a ship, you can increase your steerage by adding a burst of power and using the slipstream over the rudder to push it sideways. Very experienced pilots can turn almost on the spot at very low speeds this way, but in a tricky situation it's a judgement call whether to make a wider turn at low speed or add power and risk speeding up. For this reason it's good to have a little extra room, to make sure you can stop completely at any point and still have room to make the turn.

Dan Pichelman makes a good points in the comments. If you take a tricycle and a tail-dragger with the same turning circle, and look at the tyre marks on the ground, the tail-dragger's marks will be much bigger. That tail wheel right at the aftermost point traces out a huge circle, while the tricycle's wheels are very close together. For this reason, you need the whole turning circle to be free from obstacles such as edge markers and lights, while a tricycle can do a full turn with its tail overhanging any obstructions.

One more taxiing issue is visibility. Tail-draggers (again, especially earlier ones) are nose-high on the ground, and the engine cowling tends to prevent the pilot seeing straight forward. There have been many incidents of tail-draggers taxiing right onto smaller aircraft or obstructions straight ahead of them. (It used to be very common with Spitfires.) To avoid this, pilots are taught to weave as they taxi, so they can always check the ground ahead by looking either side of the nose. (Think of it like the clearing turns you make on a long climb.) While a tricycle might go straight along a taxiway it can only just fit into, a tail-dragger wants a much wider taxiway so that it can weave like this. You also need to plan how you're going to make the weave go into a turn when you reach a corner: if you got to the corner as you'd weaved right over to its inside, pointing towards the outside of the corner, you'd need much more room to make the turn.

For all these reasons, while it's entirely possible for a good pilot on a good day to make turns just as tight as a similar-sized tricycle aircraft, it's a good idea to allow a larger unobstructed space on straights and corners if you're expecting tail-draggers, especially students.


The fact that Total Aerodynamic Force is capitalized indicates it is a term that can be researched:
http:// www.dynamicflight.com/aerodynamics/aero_force
Total Aerodynamic Force includes drag, therefor the answer is B)
the point where the lift force acts.


Do F-22 and F-35 use force sensing flight sticks like F-16?

They move, pretty much like an F-16 stick.
From this MIT lecture "F-22 Flight Controls", Lt Col Randy Gordon, F-22 test pilot (from the transcript):

It's a side stick.
Initially it didn't move.
Eventually they decided, I'll put in some deflection.
So I can go a half inch left, a half inch right, about a quarter inch
forward, I go about a half inch back because normally I really want to
get the nose going this way.
There's some deflection to give you feedback that you've input
something on the stick, but not so much deflection that it gets in the
way of everything else you're trying to do.


What daily commercial flight is the oldest / has been running the longest?

According to the Georgia Encyclopedia one of the oldest flights operated by Delta was Love Field, Dallas to Birmingham, Alabama from 1929 up to 2000. Birmingham ist still served by Delta, but not from Love Field.

According to this the first flight from London to Schiphol was in May 1920. This route ist still in operation by KLM. But London at the time meant Croydon Airport.

On 27 May 1936 Aer Lingus made its first flight from Dublin to Bristol, while the route is also still in operation, the airfields changed. (wikipedia)

Take your pick.


Cargo airplanes are ferried empty in some situations, sure. Maintenance is a common reason, or one leg of charter cargo flights. It's pretty rare in scheduled cargo flights as it would mean there's not a single package going that direction, there's almost always something to take.


That is one of two heated drain masts for the lavatory sinks.

How does the drainage of the gray water work?


What causes the phenomenon that pilots don't believe their instruments, while they're working well?

Human decision making is an entire field of psychological research and there are many, many studies and books about it. Yet for all that we really don't know exactly why people make the kinds of mistakes they do, so I will summarize the theoretical work that I personally have studied, which are Heuristics and Cognitive Biases.

The theory is that human brains simplify decision making by developing Heuristics, which are essentially algorithms which allow for quick and efficient information processing. Think of it this way; you don't have time to analyze every situation from the ground up. Imagine if every time you walked up to the cashier in a store, went to cross a street, or from a piloting perspective became too close to another airplane you had to examine it from first principles! It would be slow, exhausting, and possibly dangerous. Heuristics are the brain's sophisticated way to shortcut that so that decisions can be made fast, they are developed through personal experience, second-hand experience, and training.

The problem is that heuristics are prone to biases and errors of logic. Heuristics can be developed which get to the wrong result with a given set of information, these lead people to making the wrong decisions, interpreting situations incorrectly when thinking about it anew would give an entirely different result. Ambiguous data can lead to the wrong heuristic being used, several options being available forces the brain to choose the best one.

I think heuristics theory goes a long way to explaining some of the common mistakes that are made in the cockpit, this is from my study of the material and from time in the cockpit, what is not that well understood is how stress and motivational factors can influence them. There's also the role of biases, which cause deviations from logic and good decision making. Some relevant ones are:

Selection bias, where someone cherry-picks what they want to see so it fits their view
Confirmation bias, where someone ignores things that don't fit their view, this is also known as expectation bias
Attention Tunneling, where someone becomes fixated on one thing and ignores others

My personal view on this is that the human brain has a tendency to force heuristics to fit input when it is ambiguous, especially in busy or stressful situations. This can be a good thing as it makes people act when they might otherwise not have, but people tend not to notice when the brain's developed ways of interpreting information don't fit the context or arrive at an obvious error. We won't like the feeling of being wrong or we are busy with other things, so we don't re-evaluate information. Sometimes people die because of that.

This is why airlines have re-curring situational training, and why that training is so incredibly important for safety. They train pilots to match what they see and feel to sets of actions so that the right decisions are made quickly.

EDIT:
There was a comment asking whether these effects could be contagious, the answer is yes, sometimes incorrect ideas get passed along, and if they don't get challenged it can lead to disaster. Some of these effects are:

Availability bias, where an event happening to one person makes another think it is more likely to happen to them. One pilot's instrument failure makes another think theirs did too, even though it's not true
Authority bias, where someone believes something is true when the source is a famous or authoritative figure. A captain telling a FO that an instrument has failed makes the FO believe it because they're the captain
Groupthink, where social pressures to conform or avoid dis-harmony make people buy into bad decisions


What is the time-lag between an airline's decision to serve a route and the starting of its service?

I work for an airline. Normally it takes no less than 6 month from the GO to maiden flight. It depends on many factors, but simplified, it goes like this:
When Commercial teams look for new opportunities, they prepares a "business case" balancing the profitability of the route and costs. Main board evaluates the proposal and gives the GO.
It is very hard to open a new route before 6 months, as all airplanes are assigned to other routes with already-sold tickets. Assigning aircraft into the new route requires a very delicate coordination to maximize each aircraft's utilization and avoid unused ground times.
Having that, you can start to sell tickets. At the same time, legal, maintenance, operations and airports teams have to run to get in place all certifications, personnel, permits, contracts and requires stuff for the route.
(Prior to all this, it is important you have an available slot in the origin/destination airports, otherwise it could take much longer.)


What is a normal EGT range of a jet engine?

Turbofan without afterburner

In non-afterburning engines the exit temperature inside the nozzle is around 600°C at full continuous thrust. If the ambient temperature is low, less heating is needed for the same thrust, and exit temperatures are lower. The maximum temperature for a given engine is, however, independent of altitude and given by the materials inside the engine. In flight the continuous maximum can be higher than on the ground, when the cooling by the external flow is less effective.

Temperature profile at a distance

This report gives results of ground measurements on the Pratt & Whitney JT8D of the Douglas DC-9 and shows how quickly the temperature drops behind the aircraft due to mixing and radiation.

Jet temperature behind a DC-9 at take-off power. Picture source.

Jet temperature behind a DC-9 at idle power. Picture source.

With afterburner

With full afterburner the engine uses approximately five times as much fuel as when running dry, and it shows in the exhaust gas temperature. This report details measurements of nozzle pressures and temperatures on one of the General Electric F-404 engines used in the X-29 program. The plot below is taken from the report and shows exhaust-jet temperature summaries in the horizontal centerline for various power settings (PLA = power level angle; 120° is full afterburner and 87° is military thrust).

Nozzle temperature survey of the GE F-404 afterburning engine. Source.

The test conditions were 30.000 ft altitude and Mach 0.3, simulated in an altitude chamber. The temperatures were measured with a rake just a few inches aft of the engine nozzle. Note that the temperatures are given in Rankine; the maximum of 3800°R is 1838°C. The wake of the engine's center body causes lower temperatures in the center of the jet at XSRL = 0. The nozzle edge is at 12.7 inches from the center; due to symmetry only one half of the jet temperature profile is shown.


How is combustion directed in one direction in a jet engine?

The shape of combustion chamber does the trick. It's expanding towards the turbine. Pressure is highest when the air leaves the last compressor disk. Fuel is added to keep pressure from dropping. The pressure it's just a bit lower but the amount and temperature of the air is much greater so the air can be used to turn turbine. To increase efficiency pressure drop is kept to minimum. If something wrong happens or throttle is advanced very fast compressor blades can be effected. The surge happens and flow direction reverses.
Look at the cutout picture of a real jet engine. It will be obvious. There are very simplified pictures of the jet engine that can make understanding confusing as they can be just wrong.


Why can not two modes coincide perfectly for some cases in Flutter phenomena?

Flutter happens when the frequency of two modes coincide. These modes must be of different nature, so their frequencies can move in different directions. Typical examples are elastic modes (with eigenfrequencies independent of speed) and aerodynamic modes (with eigenfrequencies proportional to speed). When flight speed increases, the aerodynamic mode becomes faster (think of dynamic pressure as of the stiffness of the spring in a spring-mass system) while the elastic mode stays constant. At some point both have the same frequency, but flutter will already appear when they are close enough so each builds up the amplitude of the other. This will become more efficient when the frequencies are identical, but this is academic:  When flutter starts, it is a bad idea to accelerate further.

Example for an elastic mode: Wing bending. The first mode is just the tips moving up and down, the second mode is one tip up, the other down, which will rotate the fuselage, the third mode (or for pedants: The second symmetric mode) is again both tips up, but now with the midspan section moving down and so on. They are harmonics (like the oscillations of guitar strings), so their frequencies are at a fixed ratio, with the first mode having the lowest frequency. See below, from top to bottom.

Example for an aerodynamic mode: Aileron flutter, fast-period mode (especially when coupling to the bending mode in sweptback flying wings).

For me, your diagrams don't make sense. They should look more like that:

EDIT:

With Shellp's comments I realized that the answer above is too simple. The lines in the graph are for the static case of the elastic vibration. Once this wing moves through the air, it's movement will change the local aerodynamic forces, which will modify the flutter modes. The motion-induced aerodynamic forces counteract the elastic motion at slow speeds, adding damping (negative, because they reduce the motion). With damping, the frequency of the mode is reduced.

At higher speeds, delays in the buildup of pressures mean that now the aerodynamic forces lag behind the motion, and once this lag exceeds a quarter of a period, they produce positive damping (this is an unfortunate wording, so stay with me. The damping term is a negative number when it really damps the motion, but when the term becomes positive at higher speeds, it is still called damping, but now the motion is excited instead of damped in the common sense. So let's call positive damping "excitation" from now on).
This excitation now increases the flutter frequency, so in reality the two flutter phenomena now get locked together. The first graph in the question above shows the frequency going down with speed, which looks unusual to me. The second graph shows this locking-in with an increase in frequency over speed, but at very high frequencies (it must be a small structure). If you want, the excitation is pushing the elastic frequency up, so both lock together without converging completely. But that cannot last forever - at higher speeds they should diverge, but in reality the structure is overloaded way before that happens.


How come planes can endure more positive than negative g's? I.e. how come V-n diagrams are not symmetric?

The lines start at zero load factor because with no speed there is no lift. If you move further right, the upper line is determined by the maximum lift, while the lower line is determined by the minimum lift. Both have the same value only for symmetric airfoils - regular airfoils are optimized for creating lift in only one direction.

The upper and lower maximum load factor limits of the v-n-diagram are mostly determined by maximum gust loads in level flight, and in this condition they are represented by lines emanating from +1 g, such that the distance from +1 g in terms of positive and negative load factors should be the same. Add to this that your wings will create approximately 50% more force until they reach their maximum lift as compared to the minimum ( = maximum negative) lift (the details depend on the airfoil, of course), and then your load factor limits will be 1 + 1.5$\cdot$gust load factor in positive and 1 - gust load factor in negative direction.

For an example I have uploaded the polar of a supercritical airfoil which I calculated years ago with Mark Drela's ISES. It's the best I could find quickly - most polars only show the positive maximum lift, not the limit at the opposite end.

As you can see, the maximum $c_L$ is +1.3, while the minimum $c_L$ is only -0.8.

Let's look at a practical case: Utility category airplanes must be certified for +3.8 gs and -1 g. In level flight a positive vertical gust (updraft) might add +2.8 g. The same gust strength in negative direction (downdraft) will cause a load change of only -1.9 g (because the wing will stall earlier), which, when added to the regular 1 g at level flight will translate into a -0.9 g load factor. Close enough for limiting the negative load factor at -1 g.

At higher speed the gust will not stall the airfoil in either direction, and now we can simply assume that a gust will produce a positive load of 1 + gust load factor and a negative load of 1 - gust load factor. Let the gust load factor be 2.8, and your limits will be +3.8g and -1.8g, like in your example at 150 kts.

So far, I have looked at the rationale behind the load limits for certification. But also in real life there is a difference between positive and negative load factors: The wing spar has to carry the bending moment due to lift minus the wing weight. If it would need to carry the same aerodynamic loads in both directions (up and down), the wing weight would reduce the total positive load, but would make the total negative load greater. This is why the structure cannot endure the same load factors in both directions: You need to give the wing some margin to carry its own weight in addition to the aerodynamic loads.

Things look differently if you take the v-n-diagram of aerobatic category airplanes. Now you cannot readily assume that the plane will only fly straight, but you need to assume that it will be hit by a gust while flying upside down. Add to this that the symmetric airfoil will create the same lift in both directions before it stalls, and your envelope needs to be limited at ±6 g, making the envelope symmetric.


Do aircraft carry commercial VHF radios?

No, is the short answer. Aircraft generally only carry radios covering the bands they require as standard - i.e., those covering aviation communications and navigation. I have an airband transceiver here and it can't physically be tuned that high. As far as I know, the ones in the planes I fly are identical.
I can't see any advantage in doing otherwise, as standard, as the vast majority of pilots are not licenced to talk on such bands.
In terms of citation, here's a popular general aviation radio, the BendixKing KX 165A
https://www.bendixking.com/en/products/nc/navigation-and-communication/kx-165a

Communication Transceiver: 118.000 MHz to 13.975 MHz in 25 kHz
increments, 118.0000 MHz to 136.9916 MHz in 8.33kHz increments
(118.000 - 136.990 displayed per DO 186a and ED-23B) (8.33 kHz capable
KX 165A only) Navigation Receiver: 118.00 MHz to 117~ .95 M

And, here's another:
https://icomuk.co.uk/IC-A220T/Panel_Mount_Aviation_Radio
(From the manual: https://icomuk.co.uk/files/icom/PDF/productManual/A220-TSO-Instruction-Manual.pdf)

Frequency Range: 118.000 to 136.992 MHz (8.33khz)


Are there regulatory bodies for investigating UAV accidents?

This question is rather broad, and, as worded, does not admit to a good answer beyond "no" to the first part, and "yes" to the second. That said, the rest of this answer might be useful to you.

There is no international body to investigate UAV accidents, just as there is no international body to investigate ordinary aircraft accidents. There are a great many national bodies.

In the United States, the National Transportation Safety Board is responsible for accident investigations, however, in order to get involved they would have to both know about the accident, and consider it worth investigating. The FAA requires that pilots operating under Part 107 report any accidents involving serious injury, or property damage greater than $500 (excluding the UAV) to the FAA. Presumably they would do some form of investigation to assess the remote pilot's continued suitability to hold a license. Hobbyists don't fly under part 107, however.

Other countries have their own investigation groups, such as the Air Accidents Investigation Branch in the United Kingdom. Wikipedia has a list of organizations that investigate aircraft accidents and incidents, but I have no idea how complete it is, and you would have to check each one to know what their particular policies are.


How do turbofans and piston-engines compare in terms of maintenance costs?

Your question has some areas that depend on circumstances, models, etc. but to answer in general:

Piston engines are generally fully overhauled every 1200 to 2000 hours or so. Time to overhaul one varies with the engine model, and where the overhaul is done, as it can be done at the factory, at a repair shop, or by a qualified A&P/IA (a field overhaul). A piston engine overhaul can cost as much as $25,000 or more.
Turbofan engines will likely not require major service during those 10,000 hours. Most turbofan engines are inspected regularly and continue to operate on condition unless manufacturer recommended time periods are reached or exceeded. Time to overhaul varies greatly by engine model. Costs vary greatly as well, but in the case of turbofans you're talking in the hundreds of thousands of dollars.


What to do if carbon monoxide is present?

The first thing you're going to want to do is get fresh air into the cabin, by ensuring the vents/windows are open. This will dilute the amount of CO in the cabin and stop your symptoms getting worse - allowing you to land as soon as practical.

There is also some good information online which contains further advice:

  Turn the cabin heat fully off.
  Select maximum rate of fresh air ventilation to the cabin.
  Open windows if the environment, flight profile and operating manual permit.
  Consider using supplemental oxygen if available and if doing so would not  introduce another safety or fire hazard.
  Land as soon as possible/practicable.
  Inform Air Traffic Control of your concerns and intentions.
  Select a leaner fuel mixture if possible.
  After landing seek medical attention as soon as possible.
  Before continuing the flight, have the aircraft inspected by a certified mechanic

If you're wondering about the first point, the reason is that the cabin heat is the primary way CO enters the cabin of light aircraft.

  Typically most piston powered aircraft obtain their cabin heating by directing fresh (ram) air over the engine muffler (silencer). If there are any cracks, holes or poorly fitting components in the exhaust system, then CO-rich exhaust gases can enter the cabin. Engine exhaust may also enter the cabin through inadequately sealed firewalls and wheel wells etc.


How does the hinge mechanism of plug-type pressure doors work?

This video has a clear shot of how a classic plug door (in this case of a B737) works (or search for flight attendant training videos).

You can see the door pops in (tipping a bit downwards) and then rotates on a axis in the center of the opening and then moves outside sideways. This is possible because of how the geometry works out, moving sideways negates the boor being wider than the opening and tipping down lets it fit height-wise.


In the United States, is there any way I can fly without a medical certificate?

There are lots of options for flying without a medical certificate in the United States. Most of the regulations about medical certification are in 14 CFR Part 61, Section 23.

Note that even if an operation does not require a medical certificate, it's still illegal to fly if you have a medical condition which would make it unsafe for you to fly.

Your options for flying without a medical certificate are:

Fly with an instructor, or someone else as the pilot in command (FAR 61.23(a))

You usually need a medical certificate to act as the pilot in command, but you don't need a medical certificate to merely handle the controls!

This means that you can take flying lessons without a medical certificate, as long as you have an instructor with you. The instructor will act as pilot in command, but you will get to do some (or maybe even all) of the flying.

This also means that if you have a friend who's a pilot (with a pilot's license and a medical certificate), and you and her are in an airplane together, she can let you do all of the flying! She will need to act as pilot in command, meaning that she's responsible for ensuring that everything is done safely, and for taking control of the aircraft if need be. But she can have you do the flying.

In case you're working towards a pilot's license, flying lessons received from a certified flight instructor can be logged as pilot time. If you're flying with a friend who's not an instructor, you cannot log that time.

Fly a glider or a balloon (FAR 61.23(b))

You don't need a medical certificate at all in order to fly a glider or balloon. Even without a medical certificate, you can still:

Get a solo endorsement from an instructor and fly by yourself.
Get a pilot's license and fly with passengers.
Get a commercial pilot's license and fly for compensation.
Get a flight instructor certificate and give flying lessons. (In a balloon, you only need a commercial pilot's license to give flying lessons; there is no flight instructor certificate for balloons.)

If your goal is to get an airplane pilot's license, pilot time in balloons and gliders can be counted towards that license! To get a private pilot's license for airplanes, you need 40 hours of pilot time; some, but not all, of that time is required to be done in airplanes.

Fly a light-sport aircraft (FAR 61.23(c)(1) and (2))

If you have an aircraft whose maximum takeoff weight is 1,320 pounds or less, it's probably a light-sport aircraft. If you fly a light-sport aircraft under the sport flying rules, then you can satisfy the medical requirement using a driver's license instead of a medical certificate. If your driver's license has any limitations, then those limitations also apply to your flying.

However, there's a caveat. In order to fly a light-sport aircraft using a driver's license instead of a medical certificate, you must satisfy either of the following conditions:

You have never applied for a medical certificate.
After the most recent time that you applied for a medical certificate, you were issued the certificate, and that certificate has never been suspended and revoked.

This means that if you're a licensed sport pilot, and you don't have a medical certificate, and you apply for a medical certificate, the privileges of your sport pilot's license go away until the medical certificate is issued!

Time in light-sport aircraft can be logged as pilot time.

Fly under BasicMed (FAR 61.23(c)(1) and (3), and 61.113(i))

If you've had a medical certificate in the past, but it's expired, you can still fly if you meet all the requirements for BasicMed. The main requirements are:

You must have a driver's license.
If your driver's license has any limitations, then you must also obey those limitations while flying.
You must have held a medical certificate at some point after July 14, 2006.
Your doctor must do a medical examination and sign off.
Your most recently issued medical certificate must not ever have been suspended or revoked.
Your most recent application for a medical certificate must not have been denied.
You must comply with the operating limitations in FAR 61.113(i).

Fly an ultralight aircraft (FAR 103.7(b))

If you're brave enough to fly an ultralight aircraft, good news! You don't need a medical certificate (or even a pilot's license) to fly a Part 103 ultralight aircraft.

Time in ultralight aircraft cannot be logged as pilot time.


Could airliners' wings be thinner if no fuel were stored in them?

No.

The wing thickness is primarily dictated by structural demands. It has to provide an aerodynamic fairing for the wing spar. Making it thinner would drive up the mass of the structure inside.

To simplify things, imagine the wing spar as an I-beam. It has two flanges which carry tension and compression loads, and a web between the flanges to transmit shear loads. The bending moment carried by the spar is the product of the forces in the flanges and the distance between them. If you reduce the distance, the forces need to increase to keep the bending moment constant. Bigger forces will result in bigger flanges to keep the stresses in the material below the yield stress.

Limiting the thickness is the desire to fly at a certain Mach number. A moving wing needs to push the air ahead of it aside, and thicker wings need to do more pushing. This results in a higher acceleration of the flow around the wing, and thicker wings have a lower critical Mach number (the flight Mach number when local flow reaches Mach 1). This drag penalty is especially severe in supersonic flight.

Thicker wings also help with creating higher maximum lift coefficients, up to a point. The plot below (taken from this website) shows that an airfoil thickness of 12% gives the best results, which helps to keep the wing area low. A thicker wing also makes it easier to integrate complex high-lift devices, which again helps to reduce wing area.

The resulting wing thickness is always a compromise, and the fuel volume is only the result of that compromise. If a wing needs to store more fuel, the designers will choose a lower aspect ratio, but will leave the relative thickness unchanged. If less fuel is required, the tanks will become smaller, and again the thickness will not change.


Why aren't runways lit from overhead, like highways?

Because the planes might hit them and it's not great for your vision at night. Runway edge lights are not intended to illuminate the runway they are intended to outline it. Proper runway lighting very clearly outlines a runway at night

(source)

Generally speaking there is nothing saying that a planes wingspan needs to be narrower than the runway and at some smaller airports the wings may very well be wider than the runway. This means you would need to put any high mast lights far enough away to allow aircraft clearance. In turn they would need to be quite bright due to the distance.

Another key reason and perhaps more important is to preserve the pilots "night vision". Generally when flying at night its advised to not expose your eyes to any bright lights prior to flying and to ensure that no flash lights or other bright lights go off in the cockpit while flying. This can cause your pupils to constrict making it harder to see in a dark environment. Entering a very bright runway environment all of a sudden would be strenuous on your eyes, in the event of a go around you would then have night vision issues due to the exposure in the brightly lit runway environment. As per the FAA's suggestion:

  Before and during night flight, the adaptation process of the eyes
  must be considered. First, adapt to the low level of light and then
  stay adapted. After the eyes are adapted to the darkness, avoid
  exposing them for more than one second to any bright white light as
  that causes temporary blindness. If exposed to a bright light source,
  such as search lights and landing lights, remember that each eye
  adapts to the dark independently. By closing or covering one eye when
  exposed to light, some night vision acuity is retained in the closed
  eye.


How can I learn air traffic control as a high-schooler?

Join the Vatsim network.  This is a network of simulated pilots flying X-Plane, FSX, etc., and simulated controllers.  The simulated controllers use, as much as they can in a hobbyist network, real phraseology and procedures.  I personally knew several real-world controllers who controlled on the Vatsim network in their off-time, and I know several hobbyist controllers who went on to become real air traffic controllers.

While controlling on a hobby network is not the same as controlling real airplanes, you won't learn a lot you'll have to relearn.  That's because the hobbyist controllers on Vatsim make a serious effort to follow real procedures.  When they discuss air traffic control with each other, you frequently see references to the ".65", the official bible of ATC.


How is an off-field landing accomplished at night?

Off-field landings at night are inherently more difficult and hazardous than in the day because depending on conditions you may have no way to tell what is down there. Unless you have decently strong moonlight all unlit terrain will be completely black, and you won't be able to tell forest from field. This is why it's critical to protect your night vision, it gives you a chance to see what's below you. If there's a highway down there that may be your best option, but if you're in a sparse area on a dark night you have to pick a spot that's into wind and hope it's not badlands. Even then it's still survivable if you have good technique, keep positive control of the airplane and reduce the airspeed as much as you can before impact, without stalling of course.
Aiming for clusters of lights sounds good at first, but that usually means buildings or parking lots which are not good choices.
The best way to de-risk this is through good flight planning. Choose a flight path that goes over friendly terrain: adding 15 minutes of flying time is worth it if it means you are over fields rather than rough terrain or water. Study the terrain using google earth or a similar tool. If you have a GPS you could even put good off-airport landing sites on your map. Give yourself extra altitude, and keep practicing your forced landing technique.


Is it fact or fiction that Ashgabat control tower is misplaced?

It would seem your question ends with the first part. Having checked out the airport online, checking images, maps, etc, I can't see anything wrong with the placement of the tower. It actually seems nearly optimal... It's very near the center of the airport with an unobstructed view of the whole facility, and between the 2 main runways....  Parts 2 and 3 of your question become non-operative, so yes, this is a valid question here, and need not be sent to a skeptics group.

What was interesting to me though was that the image in google maps satellite view seems to show the parking spaces around the tower completely empty... No controllers on duty the day the image was taken?


What is the average temperature in the luggage hold of a passenger plane?

According to an A320 pilot quoted in this question on travel.SE (and see this one too), the temperature can be 7C at the low end but potentially above 18C if animals are being transported. Therefore, if you want to transport something in the hold that needs to be kept at a specific temperature range you would need to check with the airline about how to do that.


Does the center of lift have to be in line with the center of mass?

In my opinion the vertical position of the center of gravity (CG) is negligible.
First of all the variation will be very small. Between an airplane with lead on the bottom of the cargo and an airplane with all passengers on the upper deck the CG will not move that much. And statistically the CG will probably be somewhat around the centerline of the fuselage.
Then, yes drag forces and engine thrust could create a tiny pitching moment but the leverage will only be a few inches at max thus the moment being very small compared to the gravity VS lift pitching moment resulting from the horizontal distance between CG and CP.
In the end question is somewhat similar to :
"what's better low or high wing planes?". On one side CG is above or near the wings and on the other hand way below the wing. Both works fine and requires only small design variations for aerodynamics stability.