Is it bad form to call "ready to depart" when you know you won't be cleared yet?

Informing the controller that you are ready to depart and requesting a takeoff clearance aren't the same thing.

It isn't bad form to inform the controller when you're ready for the next phase; if the controller isn't ready yet, you won't receive a takeoff clearance, but the good news is that now the controller is ready to get you going as soon as possible since your intentions have been declared, and she also has some time to think about what will happen next.

It opens up time for the controller to plan and coordinate.

Situation A:  You wait until the landing traffic is clear of the runway before you state that you're ready for departure, and then the tower clears you; you takeoff.

In this situation, the tower had a short time to react to your request and possibly plan other traffic around you.

Situation B:  You state that you're ready for departure, the tower acknowledges and requests for you to hold short for landing traffic. The traffic lands, and then, the tower clears you; you takeoff.

In this situation, the tower could have altered other inbound traffic to provider a bigger safety buffer for you due to the increased time given to asses the current traffic conditions at the airport.


How do you determine how much "life" an aircraft has left?

I'm going out a bit on a limb here, and it isn't specifically an answer to exactly what you are asking (which is what Stack Exchange tends to strive for), but I think this is the answer you need, so at the risk of receiving a couple of downvotes, here goes.

  engine was rebuilt 556 hours ago but was a problem because was never entered in the log books

I think that boldfaced text makes your entire question moot. In other words, the answer to your specific question doesn't really make any difference; the above tells you all you really need to know. Which is:

As Simon said in a comment, if the seller readily admits to not entering an engine rebuild into the log, then what else has not been entered into the log? Especially if you are a beginner, that's the sort of thing I would expect will come back to bite you hard.

Total time is stated as 6300, Hobbs time is stated as 7142, tach time is stated as 8131. And that's by the seller (including the mechanic's report provided by the seller). Does the difference between these figures inspire confidence in the airplane's state, the seller's honesty, and your ability to get an accurate picture of what you are buying?

As has been stated, the only person qualified to answer your question about the state of the engine in a reasonably objective manner is the mechanic who inspected the engine. The odds that this particular mechanic will stumble across this question is already quite low. What are the odds that the mechanic will not only stumble across the question, but also recognize the particular aircraft you are asking about and decide to answer the question with anything that is not already in the inspection report (which you already have received from the seller)?

More generally, with well-serviced aircraft, it isn't as easy as just saying "this aircraft has X number of hours of service left" even based on the current state of a single piece such as the (an) engine, because with good servicing it's perfectly possible to extend the service life of an aircraft for a very long time. A well-treated aircraft is a very different beast compared to perhaps a car (which might be lucky to get a checkup once a year and an oil change every few thousand miles), of course in part because the failure mode is much more serious. (If your car fails on the highway you pull over and call a tow truck; if an airplane fails in mid-flight then what do you do?)

Personally and for the specific situation you describe, I wouldn't go near that particular aircraft if I can avoid it, let alone buy it. At the very least buy something where the trivially obtainable numbers match.


Would diesel (Jet A) cause less pollution than other fuels?

This is a good question which does not have an entirely straightforward answer as the different types of pollution produced and their effects on the environment are still being studied. Also, I know of no actual studies of aero diesel versus avgas versus unleaded avgas pollution in different types of aero engines to base a conclusion off of. I will draw some parallels with auto engines and fuels as they are similar in many ways.

Comparing the efficiency and pollution of a modern aero-diesel engine to the archaic avgas engine technology in most light airplanes is not really a fair comparison because modern aero-diesel engines have computerized electronic fuel injection, and often computerized variable pitch propellers which combine to create the best efficiency for the phase of flight. Old engine technology has no electronically controlled fuel injection (often no fuel injection at all), and often they don't have the gauges installed to inform the pilot how best to lean the engine. A better comparison would be a modern aero-diesel to a modern avgas engine with similar levels of technology, that's something I'd like to see.

There are many different types of pollution, and the different types of engines produce differing amounts. I will list the major types:

CO2: If you look at it from a CO2 perspective then auto diesels are less polluting than auto gasoline engines, which is why in many places across the world people have been moving to diesel. Governments (many in Europe) have in some cases taxes diesel less to make it more attractive. Whether aero-diesel engines produce less CO2 than a comparable technology avgas engines is not certain, as I said I've seen no actual data. Aero-diesel engines are heavier than avgas engines because they are partly made of steel, but they don't need magnetos which saves some weight, but then they are turbocharged which takes weight. Looking at the auto comparison I'd say aero diesels are probably better on CO2
NOx compounds: Nitrogen oxides are linked to asthma and breathing disorders, and diesel engines produce more of these than gasoline engines
Sulphur compounds: These are also linked to asthma and breathing disorders. Jet fuel has higher sulphur content than diesel fuel, and much higher than gasoline/avgas. Sulphur compounds may actually be helping to cool the planet though, as they help form clouds (acidic clouds) which reflect sunlight back into space
Fine Particulate Matter (FPM): particulates are a biggie from an environmental and health perspective these days. Particulates are linked to asthma and breathing disorders, and there is some evidence that black carbon particulates are heating the planet and causing glacier melt at an accelerated rate as they absorb heat. Diesels produce much more particulates than gasoline engines do

There is growing scientific evidence that the health and environmental costs of particulates, nitrogens and sulphur compounds of diesel outweigh the benefits of lower CO2 levels. I know in the UK the government is thinking about a U-turn on their stance on diesels, and many people are looking at going back to gasoline engines.

The biggest polluter with avgas is the lead though, in the form of Tetra Ethyl Lead (TEL) which is extremely toxic and very expensive to deal with. Unfortunately, without the lead avgas engines can rip themselves apart because of detonation at high density altitudes. This is an edge case to be honest, most light aircraft will never be in that situation, but it is potentially deadly in enough cases that you can't just get the lead out (pun intended). The lead makes avgas much more expensive than Jet fuel, which is one of the drivers behind aero-diesel; it's cost, not environmental benefits which make it attractive.


Is there a light civilian helicopter capable of a 250 NM trip without refueling?

I would need a definition of the word 'light' as it is a little relative.  Most light turbine helicopters eg a Bell 206 JetRanger or a Hughes 500 will do this job just fine.

It is a little difficult to locate a reciprocating engine powered helo that meets those criteria.  The Guimbal Cabri G2 and the Robinson R44 would be my choices for that but cost over $300,000 a piece.

The Schweizer (now Sikorsky) S333 would be another good choice.  It is a light turbine helicopter and can be obtained for just shy of 200,000 USD, though you may be required to put another 100,000 USD or so into it.


Why two passenger airplanes travel side by side?

The top one is Baltic 634, the bottom one BT684.

As you can see they had 2000ft seperation. That's 600m for us europeans not accustomed to aviation.

Furthermore, at 17:40:19 BT634 reported in at 52.409599,16.981899. 17:40:25 BT684 reported in at 52.423222,17.019314. While those are 6 seconds apart, the planes were north-eastern course at the time, so I guesstimate that they had 1-2km horizontal seperation as well.

As to why - they're going the same place. The separation is big enough that there's almost certainly no benefit to it.


What is this aircraft that has both piston and jet engines?

It is a double-hulled "YAK-110" (which is two Yak-55's), it was only recently completed and will be at Oskosh 2018 (and so will I, so I may be able to add additional pictures in August).

Here is an article about it.

Here is another video with the jet engine at its first airshow (and the picture you have is a screenshot from it):

It also isn't the only aircraft set up this way (jet/piston), the Screamin Sasquatch is another airshow aircraft converted to have both.


Is there (some form of) penetration testing in aviation?

There is lots of testing in aviation, in every step of the process from paper designs to an actual airframe. For situation based training the aviation industry turns to the tried and true method of

Simulation

This is similar to software in many regards (and often uses computer based simulations). Simulator tech has come a long way in the past 35 years and full motion simulators are a great way to get very very close to the real thing. If you want to test out a situation where you knock out some random approach lights, throw in low visibility and some wind shear there is no reason to risk an actual aircraft, and a pilots life. Just queue it up in the sim and see how they do.

When it comes to the physical testing of say an airframe the FAA (and other bodies) also tend to take the "...before we let it out there approach" to testing and certification. In other words before an airframe is certified for production it will undergo extensive flight testing that physically pushes the airframe and exposes it to situations it should never encounter in normal flight. Omega Tau does a great episode with an Airbus test pilot that goes deep into whats involved in this, its worth a listen.

The biggest difference in aviation is that you have control over the end to end situation. In computer security you simply cant tell people "please be careful, if you use this encryption it may break in the following cases and we dont know how to fix it". On the contrary in aviation you have the ability to train pilots and more importantly you have the ability to make (or enforce) a no-go call. If we know an approach system only works down to certain minimums you simply don't fly if the weather is below them, unlike in computer security where the system is expected to always work and always be secure and in a lot of instances, always be up.


Are 'human factor' specialists consulted during the UX design of cockpit controls and avionics?

My thesis, which I wrote so long ago that I no longer recall the title, was a complete redesign of the Boeing 747 cockpit from a human factors and usability point of view.

My designs, which were submitted to Boeing at the time, likely helped create the foundation for the modern glass fly-by-wire cockpit.

At the time, glass cockpits did not exist (the term refers to the glass in the CRT monitors that were eventually used within the cockpit, later replaced by LCD displays).  Fly-by-wire, which is the concept of replacing conventional flight controls with an electronic interface, was in its infancy.

I remember working tirelessly to create a comprehensive new human interface for pilots that would minimize errors and improve safety.

My research was based in the cognitive sciences, which consisted of university coursework in human physiology, neuroanatomy (rudimentary at the time), psychology, statistics, engineering, computer science, mathematics, linguistics, neural networks (the very first ones), and artificial intelligence.  It was a rigorous and diverse education.

I spent hours and hours watching films of pilots performing a vast array of different procedures.  Sometimes they were successful, and sometimes they were not.  When they were not, it often resulted in serious consequences.  I spent long nights listening to hour after hour of dialog between air traffic controllers and pilots.  I studied detailed accident and near-accident reports.  I also interviewed pilots and spent a fair amount of time inside commercial cockpits, between flights, gathering essential data.

One of the challenges that I vividly recall was reducing complexity for pilots, while keeping the tasks difficult enough so they would stay engaged to their tasks and not fall asleep or become distracted.

The most rewarding part of developing my thesis was converting the cockpit from what I called a control-based center to a task-based center.  Up until that time, most controls available to pilots were designed to directly impact a flight control surface such as the rudder.  There were some rudimentary "intelligent" controls to perform basic horizontal and vertical navigation (but nothing that integrated the two!).

I designed a new system that was based on high level tasks that the pilot would need to perform.  No longer were ailerons, elevators, flaps, and thrust the focus.  Instead, I changed the focus of the cockpit to center on essential tasks such as taking off, landing, route planning, communications, and traffic and weather avoidance.

During this work, I learned that I had to seamlessly integrate my human factors engineering and user experience design skills.  In my opinion, and from my personal experience, they always need to be.

Whenever I fly, I ask to take a look at the cockpit after we land.  It's a joy to see the evolution of my designs.  Whether I was the originator of these designs or one of many human factors engineers who came up with them at the same time, I will never know.  But similarities of the current designs to what I proposed in my thesis many years ago gives me a little insight into a possible answer to that question.


Why doesn't G-force knock this pilot out twice?

Your body responds to a lack of oxygen to the brain with physiological responses that can take up to ten seconds to be effective.

...The brain is highly sensitive to cellular hypoxia (lack of oxygen), so rapid impaired function and almost unconsciousness follows (A-LOC), and then ultimately total unconsciousness (G-LOC). To avoid this, your body will reflexively make adjustments in heart output and blood pressure to increase blood flow to the brain (by parasympathetic response–an adrenaline surge), but it takes 6-9 seconds for this reflex to initiate.  By this time, unconsciousness has likely occurred, which obviously means no one is conscious to fly the aircraft.

Raptor 9.0g turn

In addition, the pilot likely made greater effort to avoid a second blackout.

Breathing: Rapid (< 1 sec) exhalation/inspiration cycles every 3 seconds.  This maintains oxygen content and decreases carbon dioxide in blood, while also relieving increased pressure of chest, and allowing the heart to refill with deoxygenated blood from the rest of the body.

Isometric Contraction:  Flexion of skeletal muscles of legs and abdomen.  When muscles contract, the small blood vessels in them constrict, making them smaller with less room for blood.  This step increases pressure in chest and displaces blood away from these contracted muscles into the upper body and brain.

Together, some combination of these measures would prevent a repeat blackout.


Is a CFII required in order for a flight Instructor to provide training for added class ratings?

An instructor need not be a CFII to provide training for an additional class rating to an existing instrument pilot with a category rating under which the additional class falls.
If a customer already holds a commercial airplane certificate with a single engine class rating and instrument airplane rating, an instructor does not need to hold a CFII to provide training that customer’s multi-engine class training.  My regulation walk is laid out below.  Please read it before voting or commenting.
Important note: if the customer is NOT instrument rated and is seeking the instrument rating for the category -and/or- the customer is seeking to upgrade from a PPL to a CPL or CPL to ATP, the instructor must hold a CFII/MEI.
Regulation Walk
First, when is an instructor required to hold a CFII?
61.195(c) outlines instructor limitation and qualification related to the instrument training.  This reg specifies that an instructor must be a CFII to provide instrument training for the issuance of an instrument rating, a type rating not limited to VFR, the commercial certificate, and the ATP certificate.
If we stop there it sounds like an instructor needs to be a CFII to provide training to a customer seeking a simple ME class add-on to an existing airplane SE comm-inst.  But wait…
Are we really conducting “instrument training” while preparing for an additional class rating to an existing SE comm-inst ticket?  No, we’re not.  “Instrument training” has a definition in 61.1:

Instrument training means that time in which instrument training is
received from an authorized instructor under actual or simulated
instrument conditions.

61.1 also defines “flight training” which is different from “instrument training":

Flight training means that training, other than ground training,
received from an authorized instructor in flight in an aircraft.

The training for an additional class rating to an existing airplane SE comm-inst is not “instrument training,” it is flight solely by reference to instruments and that’s an important distinction.  It sounds pedantic, but the FAA intentionally uses these two terms very carefully:
61.109(b)(3) – PPL airplane multi-engine aeronautical experience requirement

3 hours of flight training in a multiengine airplane on the control
and maneuvering of an airplane solely by reference to instruments,
including straight and level flight, constant airspeed climbs and
descents, turns to a heading, recovery from unusual flight attitudes,
radio communications, and the use of navigation systems/facilities and
radar services appropriate to instrument flight.

61.129(b)(3)(i) – CPL airplane multi-engine aeronautical experience requirement

Ten hours of instrument training using a view-limiting device
including attitude instrument flying, partial panel skills, recovery
from unusual flight attitudes, and intercepting and tracking
navigational systems. Five hours of the 10 hours required on
instrument training must be in a multiengine airplane.

Do you see the difference?  It’s carefully written to allow a non-CFII to conduct PPL ME training but requires a CFII to perform CPL ME training (which is also true for CPL SE).  But wait, there’s more…
61.109 and 61.129 are aeronautical experience requirements for the PPL and CPL certificates.  Note that our customer already holds a CPL certificate for airplane SE and an instrument airplane rating.  The instructor does not need to meet the hour requirements in 61.129 because 61.63(c)(3) [Additional Class Ratings] gives us:

A person who applies for an additional class rating on a pilot certificate…need not meet the specified training time requirements
prescribed by this part that apply to the pilot certificate for the
aircraft class rating sought; unless, the person only holds a
lighter-than-air category rating with a balloon class rating and is
seeking an airship class rating, then that person must receive the
specified training time requirements and possess the appropriate
aeronautical experience.

This means that no “instrument training” is required and that any training that takes place is “flight training solely by reference to instruments” and can be performed by a MEI without a CFII.
So, to conclude…
…a customer seeking to add a ME class rating who already holds a commercial pilot certificate for single engine land airplane with and instrument airplane rating is not receiving commercial certificate training because he/she already holds a commercial certificate.  They're merely adding another class to their commercial certificate.
…a customer seeking a ME class rating who already holds a commercial pilot certificate for single engine land airplane with and instrument rating is not receiving instrument training because he/she already holds an instrument airplane rating.  Again, just a class add-on, not a new rating.  There are no ME or SE instrument ratings, it's a category rating.
…the training received is purely multi-engine operation training and covers how to exercise the privileges of their existing commercial pilot certificate and instrument airplane rating while flying a multi-engine airplane.  It is not training for an instrument airplane rating (they already have it) and it’s not commercial certificate training (because they already have it).  It’s an additional class rating per 61.63.
…our CFI/MEI (no CFII) can give the training and endorse the customer for a practical exam.
Important notes:
A customer seeking to upgrade a cert from PPL to CPL -or- CPL to ATP must receive training from a CFII/MEI.
A customer going for an initial instrument rating must receive training from a CFII/MEI.


What is the highest indicated airspeed ever achieved in a traditional aircraft?

The world low-altitude speed record was set by Darryl Greenamyer in a rebuilt F-104 on 24 October 1977 at 988.26 mph (869.67 kts; 1'590.45 km/hr) and it wasn't really at sea level (mud lake Nevada on a hot day density altitude can be quite high so we don't know KIAS exactly). That airplane is by most considered to be the fastest due to small wind and frontal area. And it might also become one of the fastest land vehicle ever as some clever guy thought that getting rid of the wings was a good idea...

The SR-71 had a designed airspeed limit of 500KEAS. It was design for high altitude flight and they did not bother about structural strength to withstand low altitude fast flight or high g loads flight as you can see in the full flight manual.
Other jet fighter were known to fly fast at low altitude during mission like the F-4 with operating procedures of 1.34 Mach (863 mph, 759.5kts, 1,389 km/h).
Finally more recently the F-16, not known as a fast airplane was nonetheless designed the limit of 800KIAS in mind. The canopy was meant to melt at 850KIAS and the engine supposedly would blow up at 854KIAS. And numerous reports show that the pilot had to pull back the throttle in order not to exceed the 800kts limit at sea level.
The reason why we don't have higher speed recorded is just that there are no need for it, the aircraft where therefore not designed to exceed "reasonable" speed and no-one was willing to push the limit further. The risk versus benefits to bet on some engineers over-designing their aircraft so that they would fly above their limit speed is just not worth it. But I'm pretty sure if you where to "floor" a MiG-29/31 or a f15 up to failure you would certainly exceed those speed. It's like the longest flight, some records won't probably ever be tried again.


As egid pointed out, pilots typically do not file a specific approach as part of their flight plan. ATC will decide what runways and approaches are in use based on the weather. As the pilots are on their descent to the destination, they will be told which approach to expect. Pilots can always request something different but ATC is trying to get everyone to their destinations as safely and quickly as possible.

It's easier to space and sequence aircraft if they are all on the same approach, rather than trying to get aircraft on multiple approaches to mesh together just right. It's also easier to sequence them if they are all on the same approach course along the localizer, where an RNAV approach may have multiple initial fixes that follow various paths to get to the same final approach fix.

An ILS approach gives ATC more control over the spacing and sequencing of aircraft onto the final approach course. Aircraft can be vectored in anywhere along the localizer. RNAV approaches have more locations where aircraft can join them, which may be inconvenient depending on the direction from which an aircraft is arriving. Not all aircraft may be able to join an RNAV course by vectors, but pretty much any airliner can intercept an ILS localizer.

The same benefits can apply even in visual conditions. The localizer provides a common reference that all pilots can join and follow while they can maintain visual separation from each other, allowing closer spacing of aircraft. It's easier to say "join the localizer" than "join the RNAV RWY 17 final approach course."


Does headwind on takeoff affect g force?

In the takeoff run, the acceleration is less with headwind, but once in flight, the airplane flies within the mass of air. The fact that that mass may move in relation with the ground doesn't affect the magnitude of the forces involved in flight, so accelerations are not affected by the wind.


How do you calculate the lift coefficient of an airfoil at zero angle of attack?

The solution and the approximate solution to zero-lift angle of attack from thin airfoil theory can be found in ESDU 98011. The derivation of an analytical solution can also be found in Anderson, Fundamentals of Aerodynamics. $C_{l_0}$ can then be found by multipling it with $2\pi$.

Edited to add classical thin-airfoil result:

$$C_{l_0}=2\int_0^\pi{\frac{dz}{dx}(cos\theta-1)d\theta}$$
$$x=\frac{1}{2}(1-cos\theta)$$

$x$ is the chord line coordinate from 0 to 1; $z$ is the mean camber line height at coordinate $x$, normalized to the chord length; $\frac{dz}{dx}$ is the curvature of the camber line.

Now you just have to numerically integrate to get the lift at zero incidence.


Would a laser dazzler be militarily useful?

Such a system already exists (in a way) and is in place to warn pilots who improperly enter the DC SFRA area. Im not sure it "dazzles" but it is what you describe and could be extended to do so. You can see an example of it running here.


What does the letter J mean at the start of an FAA instrument approach chart identifier?

According to JO 7340.2J - Contractions p. 2-2-15 you're correct. It stands for "jet approach landing charts".


What does the Emergency Avionics switch do?

A quick google will turn up some answers. The consensus seems to be that it is just another switch in parallel with the Avionics Master Switch, such that, if the master switch fails, the "emergency" switch can be used to connect the juice instead! The point being that the master switch is a single  point of failure for the entire avionics suite (radios, transponder and nav) - if that switch fails in flight, you lose everything!

EDIT:

From the Piper Dakota (PA-28-236) Maintenance Manual:

  Electrical power for various avionics components is controlled by an avionics master switch located near
  the top of the instrument panel between radio stacks. It controls power to all radios through the aircraft master
  switch.

  An emergency bus switch is provided to supply auxiliary power to avionics bus in event of a radio master
  switch circuit failure. The emergency bus switch is located behind lower right shin guard, to left of the circuit
  breaker panel.


There are many higher-order effects. For example, yaw causes a slight increase in airspeed over the outer wing of the turn and a decrease in airspeed over the inner wing. As a result, the outer wing will generate more lift than the other, introducing a rolling motion.

Yaw also causes side-slip which triggers several effects. Wings that are swept backwards, as on the B737, contribute to the roll towards the direction of the turn, because the outer wing gets effectively longer (visual explanation) and produces more lift. Further contributing to this roll is the outer wing having a higher angle of attack due to the dihedral effect (visual explanation).

Similar effects apply to other control surfaces. It's not true that rudder only causes yaw and ailerons only cause roll. Those are simplifications, even though aircraft are usually designed for these simplifications to hold fairly well.

There is also a direct effect. The image below didn't show the center of mass; I drew in a guess as a yellow circle. It's clearly below the rudder, which is true for most aircraft. This means applying rudder introduces a rolling torque, roughly equal to the sideways component of the force on the control surface, multiplied by the distance between rudder and the longitudinal axis. The magnitude of this product is visualised as the area of the red rectangle.


How do GA glass cockpit attitude indicators handle aerobatics?

Caging was required when Gyros were mechanical masses actually spinning at many rpms in their cases. That mass resisted rotational motion and produced a resistance force that was measured and translated into useful info like pitch and roll. That spinning mass carried much momentum in the form of its mass times its rotational velocity. And too much sudden motion and the resistive force/momentum could  cause mechanical stress to the unit and/or cause the instrument to tumble. So it became helpful to cage a gyro before acrobatics to keep the thing from busting or wearing out prematurely.

In modern glass cockpits like the G1000, there are no mechanical gyros with high mass parts (excepting a standby instrument independent of the glass system, which may need caging if it's a mech type). The gyros that are used for a G1000 system are called MEMS (micro electro mechanical system) gyros which do not have a spinning mass. They have tiny metal discs that merely vibrate. When they are rotated (by pitching or rolling), the vibration dynamics change a little bit and a capacitive reactance apparatus measures this change which is directly proportional to the rate of rotation.

The MEMS gyros can take aerobatics without enduring any mechanical stress what so ever so there is no need to cage them.

The system does however, loose accuracy. The rotation rates offered by the MEMS gyros are prone to micro errors and these errors add up over time. The more rotations, the sooner the sum of all errors becomes significant. There is a software algorithm that re-aligns the system periodically and basically erases the errors (it kind of reminds the system which way is up). The algorithm uses accelerometers (like the one in your phone) to sense stable, un-accelerated motion, and at that time, the accelerators can sense gravity which points straight down. When this occurs, pitch and roll angles are keyed off the accelerometers and the rotation rates are reset to zero and the system is ready to start keying off the gyros again and adding up errors. In normal flight like touch and goes or cross country flight, there are lots of opportunity to reset the errors. In aerobatic flight there are fewer opportunities but once the aircraft eventually returns to level flight for some period of time, it will reset itself. Whether or not the error can be significant enough to be noticed by the pilot, I don't know... probably depend on many factors, but I'd probably be intimate with a sic sack by then.


What is the difference between "amended" and "revised" clearances?

An amended clearance usually indicates something has been added to it, but the original content remains the same. Revised usually means the clearance has had modifications to the original content, including possible additions and deletions.


How many angle-of-attack sensors does the Airbus A 320 NEO have?

I think there are three angle of attack sensors in all Airbus planes using fly-by-wire systems. The first two, which are arranged symmetrically near the nose are the main ones and the third one in the aft.

The angle of attack data is not typically displayed to the pilot. The computer, on the other hand displays only stall warning.

The angle of attack sensors are heated and active at  all times. The data from the sensors is received by the computer, compared (voted on) and displayed in the cabin.  The computer needs two values to agree for display.In case one fails or no two agree, the stall warning is lost.

The main use of the angle of attack sensors is their use by the computers in calculating the characteristic speeds and for providing stall warning. I don't think the pilots can monitor. let alone control the heating of the AoA sensors.


AFCS is just a fancy word for autopilot.  Autopilots for helicopters are a bigger deal than on fixed wing airplanes, due to the difficulty in flying them, so it's no small thing to develop one.  In the end however it's still just a computer than can operate servos attached to the controls to move the mechanical controls in place of the pilot when it's turned on.

Fly By Wire is a whole different universe, where there is a computer(s) between the pilot and the flight controls, with no mechanical interface at all, and the pilot makes inputs that tell the computer what the pilot wants to do, and the computer decides how to move the surfaces.


Has any Cessna Denali ever flown yet...?

According to Flying Magazine's September 2018 profile of the Denali:

  The Denali’s first flight is expected early next year, with an entry
  into service during the first half of 2020.

As for the performance figures you mentioned, the same article says:

  The Denali will weigh less than 12,500 pounds to prevent the need for
  a type rating, but at the moment, Cessna hasn’t released a gross
  weight number, nor any performance figures. Those won’t be made public
  until after the Denali’s first flight next year.


Fuel bias is as you described it. As the engine ages, it burns more fuel than a brand new one.
The fuel flow (and drag) corrections are entered into the FMS. This would allow the FMS calculated quantity not to disagree with the tanks totalizer. The figures are based off previous flights and engine tests.

Maintenance personnel can refine the database by entering correction factors for drag and fuel flow. (737 manual)

also

There are also "biases" to consider, depending on the make and model of aircraft. For example with Gulfstream aircraft, our flight planning experts typically add a 16% bias for flights of less than three hours. However, biases depend on the age of the aircraft, how the operator flies it, planned flight level, and speed.
So, it’s best practice for operators to compare actual fuel burns with flight plan burns to confirm accuracy. (Source)

Boeing does not call it bias when I checked the 787/737 manuals, but 'bias' is likely a flight planning software term.
(Source) From a flight planner for a flight sim.
(Source) Random real flight plan. Note: company software differs.
Boeing 787 FMS interface where the drag and fuel flow corrections are entered.


A flight requires pilot & copilot when the aircraft being flown requires it.

A multi-crew aeroplane is one that requires a flight crew of at least two pilots. One of them is the pilot-in-command (the captain) and the other is the co-pilot (or first officer). All jet air transport aeroplanes and the vast majority of turbine powered air transport aircraft and business jet are multi-crew aeroplanes.

The definition in Annex 1 — Personnel Licensing states that it is: "an aircraft required to be operated with a co-pilot as specified in the flight manual or by the air operator certificate."

So the secondary answer is no, it cannot be decided by a pilot or an operator, it is a statutory requirement.


How close is the air resistance or drag force to being proportional to the airspeed squared?

Subsonic aircraft drag is composed of two major components:

Pressure drag. Most of this is induced drag, but also some is from viscous effects which result in less pressure on the rear sections of aircraft.
Friction drag from boundary layer effects.

At high speed, friction can be the dominant drag contributor and here we have a less than quadratic dependency because with increasing speed the influence of friction is diminished. This is expressed by the Reynolds number and for first order approximations the friction drag coefficient changes in proportion to $Re^{-0.2}$. Since Re increases linearly with speed, the friction drag force is approximately proportional to $v^{1.8}$ at high speed.

At low speed induced drag is dominant and this decreases with speed squared. Of course, there is still a contribution from separation (which is a major problem at low speed), so the proportionality is smaller. Still, at low speed aircraft drag drops over speed.

With cars things are simpler. Here we have a rather blunt body with lots of separation at the backwards-facing surface. The suction on that separated flow is the dominant contributor to a car's aerodynamic drag and is much less influenced by Reynolds number effects. However, a small decrease in the friction drag coefficient over speed on the surfaces with attached flow remains, so the proportionality is a whisker below 2. For engineering, using $v^2$ is good enough, however.


Why is the front part of the engine not painted?

The engine inlet lip is bare metal to facilitate anti-icing. The area is heated from within using hot engine bleed air.

This partial schematic (from Boeing AERO QTR_01.12) shows the engine anti-ice valve, which controls the air supply to the inlet lip:

Interesting side note: Even the 787 "no-bleed" system architecture uses bleed air for engine anti-ice.


Do pilots have a generally preferred "traffic" resolution?

If ATC offered me a heading change or an altitude change and I was happy with the altitude I was at, I'd take the heading change in a heartbeat.  Compare:

Altitude change:

Dial the alt preselect up.
Select speed or VS mode (usually speed).
Set climb thrust.
Monitor the capture.
As the AP captures and pitches over, start bringing the thrust back to keep from speeding up until the original thrust setting is restored.

Heading change:

Select Heading Mode if in Nav mode.  If on vectors, it's already set.
Twirl the heading bug and monitor the turn.
When told to, dial the heading bug to a new heading as instructed or to a suitable intercept angle and reset Nav mode if told to resume self navigation.

Notice that with the heading change I don't have to screw around with power, which can be more hassle or less hassle depending on if you have FADEC, but in any case a lot more work than twirling the heading knob and pushing a button.


In general, how do aircraft handle differently in inverted flight versus in upright flight?

Typically, unless the CG is quite far aft (as is often the case with aircraft designed for aerobatics), lots of forward stick or yoke will be needed to keep the nose high enough for sustained inverted flight. With inadequate forward yoke or stick input, the airspeed may increase very quickly as the flight path curves earthward and altitude is rapidly lost.

This orange radio-controlled model glider doesn't even have ailerons, and it has a flat-bottomed airfoil, yet it may be flown in sustained inverted flight.  (Roll control is challenging-- inverted, the ample dihedral is very destabilizing.)  With the right technique, nearly any aircraft would likely be controllable in sustained inverted flight.  Getting there safely from upright flight, and getting back safely to upright flight afterwards, may be another matter, especially if the roll rate is sluggish.

Obviously, whether or not the engines will receive adequate fuel and lubrication to keep running during sustained negative-G flight, and what will happen to the flight controls if they do not, will vary from one aircraft to another.


Does the A320 Trimmable Horizontal Stabilizer automatically reset after landing?

If the quiz you saw is the same as this one, then please double-check it, as the one I linked has 'THS only' as the correct answer...

  Q 31: Which of the following will automatically reset after landing?
  A: THS.
  B: Rudder trim.
  C: Both are correct.

... which is more inline with the manual.

THS -- yes

The THS resets to 0° after being on the ground for +5 seconds and with the pitch attitude less than +2.5°. This is when the pitch law reverts to 'ground mode'.

  Ground mode is a direct relationship between sidestick deflection and elevator deflection, without auto trim.
  It automatically sets the trimmable horizontal stabilizer (THS) at 0 ° (inside the green band).

  (A320 FCOM)

Also see: Why is it not recommended to hold the nose up on the A320 after touchdown?

Rudder -- no

There is no similar 'ground mode' for the rudder, and the manual does not mention an automatic rudder trim reset as far as I've checked.* I doubt one exists because in an engine-out landing, such reset would catch the pilot off balance. (The SOP calls for 5° trim towards the working engine when landing with an engine out.)

The SOP also calls for checking the rudder trim is zero after start, and resetting it if it is not.

* The manuals do not always tell the full story as Captain Sullenberger learned, so it goes without saying to not use the internet for flight.


Why do some airplanes fly at a very low speed (like this one) at a speed of 433 km/h (234 knots) at a whopping high altitude of 26,500 ft?

433km/h seems really low, but keep in mind that flightradar is far from perfect. It is not uncommon that altitude, speed or position are far off, and sometimes, you see sudden jumps to more correct values when flight radar gets new data.

You can also check other sites like flightaware for particular fligt numbers, where you get a graph of altitude and speed, and can easily play back a given flight.

You didn't post a flight date, but the flights of the last few days have a speed of 600-700km/h at that position. This is below cruise speed, but the aircraft already start to reduce altitude and speed when leaving France.


Can microbursts occur at high altitudes?

Strong downbursts of air are possible at high levels also, for example in Cumulonimbus-clouds. However I wouldn't characterize them as microbursts, since the change of airflow direction is an equally dangerous and defining factor in microbursts.

(source: weather.gov.hk)
The head/tailwind parts don't exist at higher altitudes and you would experience the downdraft merely as turbulence.


Complete, unless you want to know the height of base of those TCU's!

The bulk of the information you're after can be found in AIS-GEN 3.5 Section 10.17 - AUTO METAR coding

In describing the coding used by automated systems, it gives this example

  NNNhhh/// Cloud detected, but it is unknown whether it is a convective cloud type (ie TCU or CB)

And this one

  //////TCU Towering Cumulus detected, but no information on its height or cloud cover is available

Which more-or-less covers your two questions, I hope.


Is ADS-B required for flight under class B airspace but outside the Mode C veil?

You may fly without ADSB under the Class B or Class C shelf provided you remain outside of any Mode C veil.

§91.225 tells you where you cannot fly. It says you cannot fly within the lateral boundaries of the Class B or C airspace or above the airspace. It does not say anything about under the shelf.

Here is an example of one such area:

skyvector.com

You can fly under 2,700' below the Ontario Class C and in the small slice of Class B you can fly up to 8,000' if you stay away from the Class C.

Paul Bertorelli has a good explanation on YouTube. (Updated link.)

  (d) After January 1, 2020, and unless otherwise authorized by ATC, no
  person may operate an aircraft in the following airspace unless the
  aircraft has equipment installed that meets the requirements in
  paragraph (b) of this section:

  (1) Class B and Class C airspace areas;

  (2) Except as provided for in paragraph (e) of this section, within 30
  nautical miles of an airport listed in appendix D, section 1 to this
  part from the surface upward to 10,000 feet MSL;

  (3) Above the ceiling and within the lateral boundaries of a Class B
  or Class C airspace area designated for an airport upward to 10,000
  feet MSL;

  4) Except as provided in paragraph (e) of this section, Class E
  airspace within the 48 contiguous states and the District of Columbia
  at and above 10,000 feet MSL, excluding the airspace at and below
  2,500 feet above the surface; and

  (5) Class E airspace at and above 3,000 feet MSL over the Gulf of
  Mexico from the coastline of the United States out to 12 nautical
  miles.

14 CFR § 91.225


What type of hoops do I have to jump through to launch high power rockets?

The FAR section that you are looking for is available on the ecfr website:

PART 101—MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS

More specifically, it is Subpart C— Amateur Rockets

The main regulations that apply are (see the above link for the full text of the regulations):

  §101.23   General operating limitations.

  (a) You must operate an amateur rocket in such a manner that it:

  (1) Is launched on a suborbital trajectory;

  (2) When launched, must not cross into the territory of a foreign
  country unless an agreement is in place between the United States and
  the country of concern;

  (3) Is unmanned; and

  (4) Does not create a hazard to persons, property, or other aircraft.

  (b) The FAA may specify additional operating limitations necessary to
  ensure that air traffic is not adversely affected, and public safety
  is not jeopardized.

  §101.25   Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.

  When operating Class 2-High Power Rockets or Class 3-Advanced High
  Power Rockets, you must comply with the General Operating Limitations
  of §101.23. In addition, you must not operate Class 2-High Power
  Rockets or Class 3-Advanced High Power Rockets—

  (a) At any altitude where clouds or obscuring phenomena of more than
  five-tenths coverage prevails;

  (b) At any altitude where the horizontal visibility is less than five
  miles;

  (c) Into any cloud;

  (d) Between sunset and sunrise without prior authorization from the
  FAA;

  (e) Within 9.26 kilometers (5 nautical miles) of any airport boundary
  without prior authorization from the FAA;

  (f) In controlled airspace without prior authorization from the FAA;

  (g) Unless you observe the greater of the following separation
  distances from any person or property that is not associated with the
  operations:

  (1) Not less than one-quarter the maximum expected altitude;

  (2) 457 meters (1,500 ft.);

  (h) Unless a person at least eighteen years old is present, is charged
  with ensuring the safety of the operation, and has final approval
  authority for initiating high-power rocket flight; and

  (i) Unless reasonable precautions are provided to report and control a
  fire caused by rocket activities.

  §101.27   ATC notification for all launches.

  No person may operate an unmanned rocket other than a Class 1—Model
  Rocket unless that person gives the following information to the FAA
  ATC facility nearest to the place of intended operation no less than
  24 hours before and no more than three days before beginning the
  operation:

  ...

  §101.29   Information requirements..

  ...


Are transport gliders used by modern armies?

No, there are no modern military glider forces, the Soviets kept an active glider force up until the early 60's before they retired them. All other military forces retired them before that because they really are not an effective delivery platform; they were inaccurate, often landing many miles off target, and had high rate of loss.

Gliders also tie up a large number of tow airplanes. Helicopters are much more capable, you can land troops on the tops of buildings or small clearings and are re-usable as well - gliders are generally non-recoverable as even if they are intact after landing they are often in inaccessible areas. Transport airplanes like C130s can land on very short, unprepared strips, or use the Low Altitude Parachute Extraction to deliver supplies without landing.


How to calculate camber for a balsa glider?

Welcome to Aviation SE, Samarth!

Flight duration depends not only on camber, but also launch speed, launch angle, mass, propeller diameter, propeller pitch, rubber quality, winding tightness, etc.  I assume that by "rubber powered glider" you mean rubber band powered for the first part of the flight, gliding thereafter.

Even if you somehow find optimal values for all the other parameters except for camber, it's still simplest -- and most trustworthy! -- to build several interchangeable wings for the glider, varying camber, and directly measuring flight duration with a stopwatch.


The flight director is related to the autopilot system. It displays a guide on the artificial horizon, which shows the attitude of the airplane, but does nothing to control the plane. The guide represents a reference of an airplane attitude that will follow the parameters set for the autopilot. The pilot can manually fly the plane directly where the flight director indicates, and by doing so the plane will follow the parameters set for the autopilot.

If the autopilot is engaged, autopilot flies the plane to follow the flight director. The flight director serves as a visual indication of where the autopilot wants the plane to go. Although a flight director typically accompanies an autopilot system, some aircraft have a flight director without an autopilot.

The procedure to engage them is to first turn on the flight director, which will show where the autopilot wants the plane to be, and then to engage the autopilot, which will then automatically fly the plane.

This is what the autopilot controls can look like.

Here is the Boeing flight director, visible as the crossed magenta lines in the center of the screen.


Why are some parts of the wings not protected by the wing anti-ice system in the B737?

There are always two answers to any question about why something is or is not on any particular aircraft: one regards regulation and the other practical application.
FAR § 25.1419, Ice protection, describes the certification requirement to allow transport category flight into known icing. No specific parts of the aircraft are listed, only that

(a) An analysis must be performed to establish that the ice protection for the various components of the airplane is adequate, taking into account the various airplane operational configurations; and

(b) To verify the ice protection analysis, to check for icing anomalies, and to demonstrate that the ice protection system and its components are effective, the airplane or its components must be flight tested in the various operational configurations, in measured natural atmospheric icing conditions and, as found necessary, by one or more of the following means...

The means listed and their explanation in various Advisory Circulars are rigorous, so the absence of icing protection for the leading edges of the 737 wing tips and roots is certified as adequate. This may seem obvious but regulations have been known to specify a particular solution to a problem, and could possibly have allowed certification without expensive testing if, for example, at least the middle 50% of the wing had a particular type of anti-ice installed.
Since the regs aren't responsible for this particular solution, we look to practical application. Bleed air anti ice is heavy, expensive, and reduces engine power output. Aircraft don't carry anything they don't need, so the question becomes: if you need a whole wing for an aircraft to fly, why do you only need to protect half a wing from ice accretion, and why pick the center section?
The answer to the first part of this new question has to do with critical phase of flight, which in this case is takeoff. The aircraft is heavy, slow and may need every bit of wing and available engine power. Diverting bypass air to heat the wing at this point is doubly punitive. The reason it is not necessary is because the wing (and control surfaces) are assumed to have been deiced/anti-iced by equipment on the ground. Beginning 1981 bleed air could be used to heat the slats during ground operations in the 737, and was automatically deactivated if engines approached takeoff power.
§ 121.629 Operation in icing conditions

(b) No person may take off an aircraft when frost, ice, or snow is adhering to the wings, control surfaces, propellers, engine inlets, or other critical surfaces of the aircraft or when the takeoff would not be in compliance with paragraph (c) of this section.

To satisfy this reg without ground de-ice you would have to heat two thirds of the airplane surface area, including the entire wing, which is wholly impractical. Assumption of ground deice/anti-ice allows design of onboard anti-ice to assume excess lift is available and you no longer need the whole wing. In the case of the 737, you only need to protect half the wing.
So why the center 50%? It's not always just the center, and engine power is (believed to be) the reason.

The NG series outboard slat has no wing anti-ice facility (see photo) believed to be due to excessive bleed requirements. However in June 2005 it was announced that the 737-MMA will have raked wingtips with anti-ice along the full span. This is because the MMA will be spending long periods of time on patrol at low level where it will be exposed to icing conditions.

The 737-MMA (Mult-imission Maritime Aircraft) is a modified commercial 737 airframe, known as the P8 Poseidon and described as

“A bit of JSTARS (Joint Surveillance Acquisition Radar System), a little bit of AWACS and a little bit of MC2A (Multirole Command and Control), but with the added ability to go and kill a submarine.”

Another unique feature of the P-8A is the raked wingtips. These, and the horizontal and vertical stabilisers, are electrically de-iced by electro-mechanical expulsion de-icing systems (EMEDS). EMEDS shakes the ice off the surfaces by using actuators in the cavity behind the leading edge. They can dislodge ice thicker than 0.15cm (0.06in).


What does mean PPM unit and why it is the unit of flow rate for the ASU(Air start unit)?

PPM stands for Pounds Per Minute (not to be confused with Parts Per Million, which also uses PPM), which is a unit of mass flow rate.

The specification gives the mass flow rate rather than the volumetric flow rate because the mass of air going in and out of the ASU is the same, where the volume going in and out is different because of the compression.


How should I read these abbreviations on the Airbus 320 MCDU?

These are RNAV procedures as defined in ARINC 424 used for database coding. They define paths which an aircraft must follow during RNAV departures and approaches. Every standard departure and approach can be divided into distinct sections. Each possible path starts at a point and ends at a termination point. The file format is standardized so that each and every FMS system can read the same file format. You can get an overview at this link.
This document requires pilots to be trained in and familiar with the paths and terminators used in RNAV departure and arrival procedures.

Understanding this terminology gives the pilot a vocabulary and a framework to better understand how an RNAV computer navigates.

RNAV departure and arrival procedures are constructed using legs or segments defined by a path and a terminator.

The path is how you get the, i.e. heading or course
The terminator is the event that causes the start of the next leg, or the end of the procedure.

There are 23 path terminators combinations defined in ARINC 424

13 are used for RNV departure and approach procedures
Each procedure has a two-letter code.

Example:
RNAV procedures start at an Initial Fix (IF) which can be a fly-by or fly-over waypoint, followed by:
Track to a Fix (TF)

The primary straight route segment for RNAV
The segment starts at either an Initial Fix (IF), or the termination of a previous segment.

Direct to a Fix (DF)

Defines a route segment from an unspecified aircraft present position to a specified fix/waypoint.

Course to an Altitude (CA)

Defines an outbound route segment that terminates at an altitude, not at a specific location.

Heading to an Altitude (VA)

Defines an outbound route segment that terminates at an altitude, not at a specific location
Similar to Course to Altitude (CA), but fly an uncorrected heading without regard to wind or ground track.

Course to  a Fix (CF)

Defines a wind-corrected course to a specific fix
Frequently used as the final segment of an approach

Course from a Fix to an Altitude (FA)

Segment begins at a defined fix/waypoint
Requires a wind-corrected heading to maintain course
Terminates when the aircraft reaches the assigned altitude, not a specific location
Common in missed approach procedures.

Others:

Course from a Fix to a Manual Termination (FM)
Heading to a Manual Termination (VM)
Heading to an Intercept (VI)
Constant Radius arc to a Fix (RF)

Every RNAV departure and approach is made up of a combination of the these paths and terminators.
King Schools has an online course for P-RNAV.


What happens when you put vortex generators on both sides of a symmetrical vertical tail?

Just because VGs can delay the flow separation (with no guarantee of success), it doesn't mean you have increased your tail volume. In fact, you have the exact same tail volume unless your vertical tail is separating at small sideslip, which probably indicates bad design or bad manufacturing.

If the VGs do increase the max Cl, it means you may be able get to a higher slip angle, perhaps more crosswind capability if your rudder is up to the task.


What scale is the speed trend line on a PFD's ASI?

I found some training material on Airbus PFDs which explains:

  A vertical arrow, called the speed trend arrow, indicates the aircraft's
  predicted speed in 10 seconds if the current acceleration or deceleration rate remains constant.

Put another way, if you measure the acceleration in knots per second, and then multiply it by ten, it's on the same scale as the speed tape.

If you want to reach a particular speed in ten seconds' time, adjust pitch or power to put the head of the arrow on that tick on the speed tape, then keep adjusting to keep it on the same tick as it approaches.


Is there a KPI to measure average hours flown?

I want to set a KPI to measure average hours flown.

You might want to check block hour:

  (aviation) The time from the moment the aircraft door closes at departure of a revenue flight until the moment the aircraft door opens at the arrival gate following its landing. Block hours are the industry-standard measure of aircraft utilization.

(Emphasis mine.)

The Wikipedia article airline cost glossary lists very common terms and KPI's.

One of those terms that could also be applicable to your case (revenue passenger miles) was asked about here: Which aircraft type flies the most annual passenger-miles?


Why does 14 CFR have skipped subparts as seen in the ASA 2019 FAR/AIM book?

Some of them were renamed/reorganized in 1989 based on proposals/petitions by the AOPA (referenced in FSIMS).

91.102 became 91.143 Flight limitation in the proximity of space flight operations.
91.104 became 91.141 Flight restrictions in the proximity of the Presidential and other parties
91.106/108/110/112/114 did not exist
91.116 became 91.175 Takeoff and landing under IFR
91.118/120/122/126/128 did not exist

The "did not exist" ones are probably proposed legislation that was removed prior to it being introduced into the Code of Federal Regulations, or regulations that were removed earlier (I can't find an older version of the CFR to check).


How long is spin training good for in the USA?

CFI candidates receive a spin training endorsement with no expiration date. According to AC 61-65E (the endorsement appendix), it should look like this:

  46. Spin training: section 61.183(i)(1).

  I certify that (First name, MI, Last name) has received the required training of section 61.183(i). I have determined that he/she is competent in instructional skills for training stall awareness, spin entry, spins, and spin recovery procedures.

  /s/ [date] J. J. Jones 987654321CFI Exp. 12-31-05

The basis for this is that 61.183 doesn't specify a time period in which the endorsement must be received:

  §61.183   Eligibility requirements.

  To be eligible for a flight instructor certificate or rating a person must:

    [...]

    (i) Accomplish the following for a flight instructor certificate with an airplane or a glider rating:

      (1) Receive a logbook endorsement from an authorized instructor indicating that the applicant is competent and possesses instructional proficiency in stall awareness, spin entry, spins, and spin recovery procedures after providing the applicant with flight training in those training areas in an airplane or glider, as appropriate, that is certificated for spins; and


How does the a movement of the cyclic control stick in a helicopter affect the swashplate?

Horizontal displacement: Tilt the rotor

With the rotor blades rotating around a vertical mast, the total lift vector of the rotor is vertical and the helicopter hovers. If a translation is desired, this vector must be tilted so that an horizontal component can appear. This is done by tilting the rotor disc. The rotor disc is the plane of rotation of the blades.

Rotor tilted forward: The helicopter moves forward.

Rotor tilt: Change blades pitch

The rotor disc is tilted using the lift difference between individual blades. For instance to tilt the rotor forward, each blade creates more lift when it is aft of the mast, less when it is forward of the mast, and the change is progressive between these two positions. The lift difference creates a torque moment on the mast, tilting the mast and the helicopter with it, at least this is our intuition.

As you mentioned, the force doesn't produce its effect instantaneously due to the gyroscopic precession. It is effective only 90° later. So the lift variation must have an advance of phase of 90°. For a forward translation, the lift is maximum when the blade is on the left, and minimum when it is on the right. The momentum is stored into the blade and released 90° later.

The variation of lift is done 90° in advance.

Lift depends on the angle of attack of the blade. Varying the amount of lift according to the position around the mast leads to varying the AoA around the mast: Increased AoA on the left, decreased on the right.

Pitch varies according to the radial position of the blade.

Change blades pitch with the swashplate

Changing the pitch of a blade is done using a system of swashplates. A stationary plate is oriented in space by the pilot using the cyclic stick.

Another plate is maintained in contact with the first one, but can turn freely with the rotor. This second plate is forced to rotate in the plane of the stationary plate, thus it oscillates constantly as it rotates. In turn, it creates an oscillation of the vertical rods (horn links). Each horn converts the rod oscillation into a pitch oscillation on the blade. The blade is now pitched according to its instantaneous radial position relative to the mast, and according to the cyclic stick command.

MBB Bo105, based on photo by Burkhard Domke (source)

Horns are linked to different angular sectors of the swashplate

The vertical rod transmits the stationary swashplate height at its current axial position. By locating the rod 90° ahead of the blade, the link takes care of the rotor precession. The mechanism is so that when the pilot pushes the cyclic forward:

The swashplate is tilted forward.
When a blade moves left of the mast, its horn link measures the height of the stationary swashplate in its aft sector, where the plate is the highest.
The horn is pushed by the link to the maximum, and the blade in turn gets the largest pitch angle.
The situation is reversed when the blade arrives on the right. The link is in contact with the forward sector of the swashplate, where the latter is at the lowest position. The blade gets a low pitch angle.

(Redrawn from source)

Advance for pitch order can be adjusted as required

By adjusting the offset of the horn link which interfaces the horn and the plate, one can adjust to the exact amount of advance required for a given blade.


On a "Visual Approach", do I execute a "missed approach" or do I go around?

First, a caution: IFR procedures can (and do) vary between countries. It is incumbent on the pilot to study the respective authority's Aeronautical Information Publication (AIP) to understand local procedures before flight. When asking questions about instrument flight procedures, it is helpful to know which countries you are specifically traveling through. While the vast majority of countries simply adopt ICAO procedures, many have significant deviations (the United States included).

ICAO Doc 4444 (PANS/ATM), section 6.5.3 discusses instrument flight that terminates into a visual approach. Interestingly, the document is silent on what happens if the approach is aborted.

In the United States, the FAA is more explicit. In the Aeronautical Information Manual, section 5-4-23 visual approaches are specifically addressed. Paragraph (e) details what should happen if a visual approach is terminated:

  A visual approach is not an IAP and therefore has no missed approach segment. If a go around is necessary for any reason, aircraft operating at controlled airports will be issued an appropriate advisory/clearance/instruction by the tower. At uncontrolled airports, aircraft are expected to remain clear of clouds and complete a landing as soon as possible. If a landing cannot be accomplished, the aircraft is expected to remain clear of clouds and contact ATC as soon as possible for further clearance. Separation from other IFR aircraft will be maintained under these circumstances.


When an airliner gets lost, and receives warning shots from interceptors, how should the pilots react in order to save the aircraft?

First off there are established interception procedures under international law so they are not going to shoot at you upon overtaking you.  Typically an element of fighters form up on the jet with the leader maneuvering into formation on the jets 9 O’Clock and the Wingman stays on the jet’s six.  They will do so in a manner which allows the intercepted aircraft to see the lead fighter.  There are a series of established visual signals ie rocking wings for compliance, deploying flaps and landing gear, etc.  if the intercepted aircraft cannot communicate with the fighters or ATC, they will squak 7600 and ATC can relay this to the fighters.  Other means can be employed to get the attention of the intercepted aircraft such as the lead fighter cutting in front of the intercepted aircraft while in afterburner, etc.

If it does come down to where the authorities determine you are a threat and use of deadly force becomes authorized, the fighters are going to let you know in a clear and unmistakable way.  Unless you are armed and intend to engage, you better comply!


What are en-route VHF marker beacons (75 MHz)?

En-route marker beacons are close relatives of the outer/middle/inner markers used on ILS approaches. Airway markers use the same audio frequency as inner markers, and some older equipment has indicators for airway/outer/middle. Older versions of the FAA AIM discuss marker beacons, but later versions omit them.
From Wikipedia:

From the 1930s until the 1950s, markers were used extensively along airways to provide an indication of an aircraft's specific position along the route, but from the 1960s they have become increasingly limited to ILS approach installations. They are now very gradually being phased out of service, especially in more developed parts of the world, as GPS and other technologies have made marker beacons increasingly obsolete.
The airway marker was used to indicate reporting points along the centerline of now obsolete "Red" airways
They are only used on a few instrument approaches anymore, to mark positions along the inbound course, when there is only one marker present

The example cited on Wikipedia (KSEE) used to have a marker as part of the LOC-D approach, but it appears that this was replaced with the YAGSU waypoint (and more recently, the DEBEY waypoint). Another example is KSLE where the ARTTY intersection on the LOC BC 13 approach used to have a marker but no longer does. I haven't been able to find any current procedures still using one.


Does low pressure induces high velocity or high velocity induces low pressure?

Neither! The cause is wing moving through the air, and the effect is a fairly complex flow pattern around it that produces lift (and wake vortex).
We know that the flow obeys certain laws (that are largely averaging of the microscopic laws governing individual molecules). One of them is law of conservation of energy, which for fluids is known as Bernoulli's equation. But that's just one equation with many free variables, so alone it is not enough to explain anything. You need the complete set of Navier-Stokes equations to be able to describe the flow.
The equations are partially differential, and need to be evaluated for every point in space and time, which can only be done approximately and requires a computer.
There is only a few conclusions that can be made using conservation laws without this, the most important probably is the existence of downwash. The third law of motion tells us that if upward force, lift, is applied to the wing, downward force is applied to the air, and second law of motion tells us that this force accelerates the air downward. The boundary between downward moving air behind the wing and the still air outside the span is the wake vortex.
But again, neither is cause and effect. The laws of physics work both ways. They just tell us that these phenomena always occur together. But the cause is the situation. We just know that both or neither will occur.


Can a pendulum stabilizer for airplanes really work?

As you noted, a pendulum can only "measure" pitch and roll angles when the pivot point is not accelerating.  Except, of course, if the length of the pendulum is the same as the Earth's radius — in which case we have a Schuler Pendulum.

Ed Carsten's pendulum stabilizer attempts to use the same principle as an autopilot measuring roll and pitch angles, and then generating elevator and aileron commands to level the aircraft. But this cannot work when using a pendulum of practical length since the roll and pitch angle "measurements" are in fact combinations of attitude angles and horizontal accelerations.


Many of the modern flying apps like Foreflight do most if not all of these calculations for you once you have programmed your aircraft parameters in. As mentioned in my answer to your other question a good deal of this data is specific to the plane. W&B is specific to every aircraft and will vary depending on how the plane is setup. Things like takeoff performance and fuel burn are generally similar for an airframe but since some aircraft have multiple propellor or engine configurations available there is a variance in the numbers. Foreflight allows you to program in climb, cruise and decent fuel burn and will calculate fuel usage for you. If you have target airspeed (climb, cruise, decent) in it will calculate time en-route for you, and you can select your altitude for wind/heading calculations. The only thing I'm not sure foreflight does is takeoff distance (yet).

I have not spent any time behind a G1000 yet but I am under the impression that the various newer glass panel options can do some of these calculations as well.

Larger aircraft have FMS systems to aid in a great deal of this once you get out of the GA world.

You could try and digitize some of the functions within some of the more common POH's (C172, the various Cherokees, C150 etc) but that would not technically be legal for flight since its not the POH for the specific airframe.


How does an altimeter deal with the non-linear pressure gradient?

It uses a model called The International Standard Atmosphere (ISA) - so may be inaccurate if you don't have one of those to fly through :-)


How can I renew my non-current Indian CPL?

This is for CAA , each country might have a different rule but in general this is the rule . If you haven't flown in India since 2001 then your license has been expired. So I assume that if you have any other license valid , you have to go to Indian civil aviation with your current  log book and they will request a confirmation from the country that you have got your license from to be sure that your license is still valid in that country.Then you have to do the conversion requirements which generally are 4 exams (for most countries are Law,HP,Nav, Met) and then you also have to go to any ATO in India and you must undergo sufficient ground and flight training for the same category aircraft that you have your other license on , and then do a oral exam and flight test .

If you haven't flown in the last 10 years , you have to do all CPL exams again .
Good luck.


Can you disengage A320 autopilot with stick pressure?

Yes. I’m not sure of the amount of force, but from the A320 FCOM:

  AP DISENGAGEMENT

  AP1 or 2 disengages when:

  The pilot presses the takeover pushbutton on the sidestick.
  The pilot presses the corresponding AP pushbutton on the FCU.
  The pilot pushes on the sidestick harder than a certain threshold or moves on the rudder pedals above a threshold.
  The pilot moves the pitch trim wheel beyond a certain threshold.
  The other AP is engaged, except when localizer/glideslope modes are armed or engaged, or when the rollout or go-around mode is engaged.
  Both thrust levers are set above the MCT detent and the aircraft is on the ground.
  The aircraft reaches the MDA-50 feet (MDH-50 feet), or 400 feet AGL if no MDA/MDH, with APPR mode engaged and a non-lLS approach is
  selected.
  One of the engagement conditions is lost.

  Furthermore, in normal law with all protections available, the AP will disconnect if:

  High speed protection is active;
  Angle-of-attack protection is active (α prot + 1° is reached);
  Pitch attitude exceeds 25° up, or 13° down, or bank angle exceeds 45°;
  A rudder pedal deflection is more than 10° out of trim.

  The standard way for the flight crew to disengage the AP is to press
  the takeover pushbutton on the sidestick. When the AP is OFF, the
  associated FCU pushbutton goes off. and "APl" (or AP2) disappears from
  the PFD’s FMA.

  *emphasis mine


When/How may I replace the Turn Coordinator with an Artificial Horizon?

The How It Flies in section on Spiral Dive Recovery mentions:

If you don’t have good outside references, you should not rely on the attitude indicator (artificial horizon). The attitude indicator contains a gyro mounted on ordinary mortal gimbals, which can only accommodate a limited range of pitch and bank angles. A steep spiral can easily cause the gyro to tumble, whereupon it will need several minutes of relatively straight and level flying before it can re-erect itself. Military aircraft have non-tumbling attitude indicators, but you’re not likely to find such things in a rented Skyhawk. Therefore, you should roll the wings level by reference to the rate-of-turn gyro.8 Being a rate gyro (as opposed to a free gyro) it has no gimbals, and therefore can’t possibly suffer from gimbal lock.
8 That is, the turn needle or turn coordinator, whichever you happen to have.

And in section on Spin Recovery it adds:

If you get into a spin in instrument conditions, you should rely primarily on the airspeed indicator and the rate-of-turn gyro. The inclinometer ball cannot be trusted; it is likely to be centrifuged away from the center of the airplane — giving an indication that depends on where the instrument is installed, telling you nothing about the direction of spin. The artificial horizon (attitude indicator) cannot be trusted since it may have tumbled due to gimbal lock. It is better to trust the rate-of-turn, which cannot possibly suffer from gimbal lock, since it has no gimbals. Remember, it is a rate gyro (not a free gyro), so it doesn’t need gimbals.

If you have good enough artificial horizon designed to avoid gimbal-lock, the you don't need turn coordinator. But with ordinary artificial horizon the turn coordinator combined with vertical speed indicator (despite it's problems like rather slow reaction time) are useful backup for recovering from in-flight upsets.


With a higher flight velocity (still subsonic), the supersonic pocket on the upper side of the wing starts earlier and takes longer until it collapses into the shock. That is quite normal, as the speed over the whole upper wing is increased with increasing flight speed.

Think of what happens at the extreme case of accelerating flight speed towards Mach 1: Now the shock will move towards the trailing edge with increasing Mach number and will stay there once the flight speed is above Mach 1 (NOTE: This is valid only for straight wings; correct the Mach number upwards for sweep effects).

Things become nasty when the shock interacts with lift creation and starts to fluctuate back and forth - this creates a buzzing sound and might even cause flutter. The mechanism is that the stronger shock causes flow separation and lift loss, which in turn shrinks the shock, which allows lift to recover so the shock grows again. With the growth, the shock moves back and jumps forward when it becomes weaker. This back-and-forth jumping of the shock creates not only a fluctuation of lift, but also of pitching moment.


Do bigger aircraft make a bigger sonic boom?

The short version is that yes, larger aircraft create bigger sonic booms, but you still have to be flying very low (less than 100 ft.) and really trying hard in order to damage glass.

A sonic boom is so complicated that you will not find a simple formula to determine the strength.  This article describes a modeling tool called PCBoom3 which can be used for sonic boom calculations.

According to several different sites, like this one and this one, the size of the aircraft does affect the intensity:

  Factors Affecting Sonic Boom Intensity

  The intensity of sonic booms are affected by:

  Weight, size and shape of the aircraft.
  Altitude
  Attitude—orientation of the aircraft’s axes relative to the its direction of motion.
  Flight path.
  Atmospheric and weather conditions.

  As the size and weight of the aircraft increases, the intensity of the
  sonic increases. This is because a larger aircraft displaces more air,
  and a heavier aircraft needs a greater force of lift to sustain
  flight. Thus creating a louder and stronger sonic boom.

and

  General Factors Associated With Sonic Booms

  There are several factors
  that can influence sonic booms -- weight, size, and shape of the
  aircraft or vehicle, plus its altitude, attitude and flight path, and
  weather or atmospheric conditions.

  A larger and heavier aircraft must displace more air and create more
  lift to sustain flight, compared with small, light aircraft.
  Therefore, they will create sonic booms stronger and louder than those
  of smaller, lighter aircraft. The larger and heavier the aircraft, the
  stronger the shock waves will be.

NASA says that a typical sonic boom for the F/A-18 is about 1.4 psf and a different NASA page goes on to say:

  Overpressure Sonic booms are measured in pounds per square foot of
  overpressure. This is the amount of the increase over the normal
  atmospheric pressure which surrounds us (2,116 psf/14.7 psi).  At one
  pound overpressure, no damage to structures would be expected.
  Overpressures of 1 to 2 pounds are produced by supersonic aircraft
  flying at normal operating altitudes. Some public reaction could be
  expected between 1.5 and 2 lb.  Rare minor damage may occur with 2 to
  5 lb overpressure.

  As overpressure increases, the likelihood of structural damage and
  stronger public reaction also increases. Tests, however, have shown
  that structures in good condition have been undamaged by overpressures
  of up to 11 lb.  Sonic booms produced by aircraft flying supersonic at
  altitudes of less than 100 feet, creating between 20 and 144 lb
  overpressure, have been experienced by humans without injury.

  Damage to eardrums can be expected when overpressures reach 720 lb.
  Overpressures of 2160 lb would have to be generated to produce lung
  damage.

  Typical overpressure of aircraft types are:

  SR-71: 0.9 lb, speed of Mach 3, 80,000 feet
  Concorde SST: 1.94 lb, speed of Mach 2, 52,000 feet
  F-104: 0.8 lb, speed of Mach 1.93, 48,000 feet
  Space Shuttle: 1.25 lb, speed of Mach 1.5, 60,000 feet, landing approach

They also include a graphic that shows the difference in sonic boom between the F-18 and the Concorde, with the Concorde having a much greater sonic boom at the same alittude:

This article specifically covers glass:

  Glass. Poorly mounted, undamaged glass in the greenhouse was chipped
  by impact against nail holding points at a sonic boom overpressure of
  12.1 psf. The same type of glass, which was already damaged, was further damaged at a designed overpressure of 7.9 psf. A large
  one-ninth of an inch thick window, intentionally precracked from
  corner to corner, was further damaged by booms of an average 6.5 psf
  overpressure.

So typical sonic booms generated by normal aircraft aren't going to create anywhere close to the 12.1 psf that they say is needed to chip "poorly mounted" glass, but the strongest sonic booms can get well over this.


Are there winglet modification regulations?

In the U.S., changing anything on the wing is considered to be a "Major Repair/Alteration" according to the FAA (FAR Part 43 - Appendix A)

To make those changes, this form - http://www.faa.gov/documentLibrary/media/Form/Form_337.pdf needs to be completed.

As you can see, it requires a certified mechanic to handle the work after which a person with Inspection Authorization would approve the aircraft for return to service.

A little extra reading - Who can perform different maintenance checks?.


Why should isobars be aligned with the leading edge of the main wing for a transonic cruiser?

I finally found several arguments to answer this question from different sources.

Sweep and Mach Number from Airbus

This argument is developed in an Airbus magazine from 1985. To grasp it it is important to understand the purpose of swept wing. By sweeping the main wings one introduces an angle between the leading edge of the wing and a line perpendicular to the fuselage axis. Let's consider two airplanes, one with swept wings (A) and one with straight wings (B).

One of the most important parameters is the Mach Number experienced by the wings. It is measured normal to the leading edge of the wing which means that for the two airplanes flying at the same Mach Number, the Mach Number seen by wings of (B) is larger than the one seen by the wings of (A). This allows to fly at higher speed because it delays the large increase in drag (drag divergence) and other effects linked to the Mach Number around the airfoil.

However, if the isobars on the wing are not aligned with the leading edge, they are following a less swept pattern which tends to reduce the benefits from the sweep angle of the main wing because the effective sweep angle is smaller and the Mach Number around the wing should not be computed normal to the leading edge but normal to the isobars close to the leading edge.

From a theoretical point of view it would even be better to have isobars not aligned with the leading edge but having a larger sweep angle. However this never happens due to boundary conditions at the root and the tip of the wing.

Other sources

All this is also explained here.

Finally, this last source deals also with the matters but does not justify the need for the isobars to be parallel to the leading edge. It deals more with the shock on the wing and the ways to weaken it and thus reduce the drag.


Could low pressure compressor blades be made of aluminum?

The answer is yes, and they have been, in the early days. The blade speed is lower than can be reached using titanium or steel, so more stages are required.


How can an F-22 Raptor reach supersonic speeds without having supersonic inlets?

The jet uses a fixed, rhombohedral shaped jet intake combined with a serpentine intake duct.  It allows for speeds just north of Mach 2 without the need for a variable geometry inlet to prevent shockwave ingestion.


What are the general post flight sequence checks and do they start automatically? If so, when?

All checklists are initiated by either the pilot flying (PF) when between takeoff and touchdown, and the captain (CA) on the ground.  In addition to checklists is the concept of flows, which are a muscle memory sequence of buttons to press / switches to flip / things to touch that are performed by the appropriate pilot before the checklist is called for.  The flows will happen automatically when the pilot responsible knows they should happen and the checklist will be called for when the responsible pilot is ready for it.

For example, when landing, the PF will perform the landing, the deceleration and sometimes the high speed turnoff before control is transferred to the CA for taxi.  Once the CA is taxiing and the airplane is cleared of the active runway, the FO will automatically start the after landing flow and call ground control.  Once taxi is underway, the CA will call for the after landing checklist.

Once parked at the gate, both pilots will do their portion of the parking flow and then the CA will call for the parking checklist.

Finally, if no crew is waiting to receive the aircraft and you are not keeping the aircraft then the FO will perform the postflight inspection and the pilots will perform the terminating checklist.  If you are keeping the plane, the FO instead does a combined post/preflight inspection and begin normal pre-flight actions.

While these actions are all started by humans, the closest thing to automatic actions are the flows.  To summarize the above, with general criteria for starting flows:

Landed, clear of the active runway, CA has the plane -- perform after landing flow
Parked at the gate -- perform parking flow.

Each of these flows are backed up by checklists called for the CA.


The Soviet Yakovlev Yak-38 (and also the Yakovlev Yak-141) had an automatic ejection seat. The aircraft had two smaller engines for VTOL. If one of them failed, the seat ejected automatically once the aircraft rolled past 60$^\circ$. From airvectors.net:

  The pilot sat on a K-36VM ejection seat, with the ejection performed automatically in takeoff or landing excursions using an "SK-EM" system. The SK-EM system was automatically engaged after the aircraft rose a few meters from the deck; it could be turned off manually, or would turn itself off if the vectored-thrust nozzles were more than 67 degrees to the vertical.

These ejection seats were first developed for Yakovlev Yak-36 (though never installed on them). The Yak- 36 had two side-by-engines, the failure of any one of which could flip the aircraft- this led to the development of an automatic ejection system that would activate aircraft seemed to be departing from safe vertical-flight parameters.

According to ejection-history.org.uk, 18 automatic ejections have been recorded in Yak-38s.


Why wasn't the 737 MAX's landing gear lengthened enough to mount the engines under the wings, rather than in front of them?

The main gear sits between the wings and retracts inwards, such that the wheels will rest in the lower fuselage. Lengthening the main gear would either require to shift the gear attachment points outward or to retract one leg a bit forward and the other a bit backwards, such that both wheels will sit behind each other instead of side-by-side, as they do now - see below (source).

Shifting the gear attachment points out is clearly feasible but results in a major wing redesign. That would cost money so Boeing management decided that a software fix would be the better solution.

Placing the wheels in tandem would equally be a major and costly modification. A lot of systems would need to be relocated and all modifications would require testing. Boeing management cleary did not want to pursue this option.

Another quick fix is shortening the gear upon retraction. Decompressing the oleo strut in order to shorten the gear upon retraction is already standard in many fighter jets. Another solution is to add another hinge such that the gear leg will fold inside the gear bay. Such a solution was used on the Grumman F-8F Bearcat and is pictured below (source).

From what I understand, this particular solution was applied to the longest 737 version to allow enough tail clearance for rotation, but added weight and complexity. Of course it could be applied to the rest of the 737 MAX fleet as well, but again Boeing management tried to save money and weight by implementing a software-only solution.

But the engine location would be fine if a larger horizontal tail would be added, increasing stability at high angle of attack and making a quick software fix unnecessary. Again, this would add cost and weight and make the aircraft less competitive.


How to start up a Lockwood-Hiller Valveless Pulse Jet?

The key to the operation of a valveless pulse jet is the oscillating shock wave created by repeated explosions in the combustion chamber. In this video they talk about using a spark plug to trigger these explosions initially, and once the engine is running the process is self sustaining.

Looking at your video I don't see any connections to the engine except the fuel pipe, and you seem to be attempting to start the engine by pushing some burning material into the combustion chamber. This will not create an explosion, so the shock wave that keeps the engine running won't be created either.


Can US pilots fly VFR OTT and/or VFR at night in Canada without additional ratings?

It looks like if you have a foreign instrument rating you automatically have VFR OTT privileges, but for night VFR you still need a Canadian night rating.

CAR 421.44(7) for VFR OTT:

  An applicant who holds or has held an instrument rating issued by a
  Contracting State shall be considered to have met the Knowledge,
  Experience and Skill requirements specified above

As for night VFR, 421.42 doesn't have any equivalent section that gives credit for foreign qualifications.


What is currently the longest commercial flight in terms of distance?

According to Wikipedia, the flight you are referring to, SQ21, got discontinued in November 2013. The runner up, still from Singapore Airlines, SQ37, got discontinued one month earlier.

The same page reports that QF8 is the current holder of the title of "longest non-stop flight" and has the same destinations as today's QF7 as of February 2017 Qatar Airways flights 920/921, covering 14,534 km (7,848nm / 9,031mi) from Doha, Qatar (DOH/OTBD) to Auckland, New Zealand (AKL/NZAA), beats QF8 by about 395 NM.

If we instead include 1-time-only flight by a commercial airliner, the longest one has been flown in November 2005 between Hong Kong and London, as a demo by Boeing.

The title of absolute longest flight without refueling is instead held by a non-commercial flight done in an aircraft specifically built for the purpose.


"What's our vector, Victor?": What does this mean?

A vector is defined by a direction and magnitude.  In aviation these represent your heading (the direction) and your speed (the magnitude).  However, in normal aviation usage "vector" only refers to the heading and other nomenclature is used to assign/report speeds.

Example:

"Jetlink 1234, Cleveland Center, turn left heading 250 for traffic"

In which case the vector assigned by ATC is 250 degrees, or 20 degrees south of magnetic west.

To answer the question "What is our vector, Victor?", Victor should state the heading they have been assigned to fly from ATC.

An alternative question would be "What is your heading?" and then you would answer with the direction you are currently flying.


How many bird strikes are there per year? Any world-wide statistics?

Bird Strikes Worldwide

From Hedayati, R., Sadighi, M., Bird Strike, 2016:

  According to currently available data, it is estimated that a bird-strike event occurs once every 2000 flights (Khan, Kapania & Johnson, 2010). Further analyses of bird-strike statistics have shown that only 20% of bird strikes are actually reported by aviation staff. This means that the extent of economic and human losses resulting from bird strike could be much higher than what is currently presumed (Chuan, 2006). Consequently, this suggests that conducting further indepth studies on how to better capture reliable bird-strike event statistics and formulating strategies and solutions
  would be beneficial.

From EASA, Bird Strike Damage & Windshield Bird Strike - Final Report, 2009:

  It had been intended to use the International Civil Aviation Organization (ICAO) database of bird strike statistics as a prime source of bird strike information, giving details of worldwide bird strike incidents and accidents. However, despite the best endeavours of fera, Atkins and EASA, it was not possible to gain access to this source of information. Therefore the literature search does not include data from regions such as Asia and Australia. Reporting levels from these regions are low and it is likely that even with access to ICAO data, there would be limited useful information available beyond that already available from UK and USA/Canada sources. It is estimated, based on previous fera Bird Management Unit experience, that the UK and USA/Canadian data obtained represents approximately 50% of all worldwide bird strike reports. Also regions such as Russia, China and South
  America do not routinely contribute data to the ICAO database.

Wildlife Strikes in the United States of America

From FAA, Wildlife Strikes to Civil Aircraft in the United States 1990-2014, 2015:

  The number of strikes annually reported to the FAA has increased 7.4-fold from 1,851 in 1990 to a record 13,668 in 2014. The 2014 total was an increase of 2,267 strikes (20 percent) compared to the 11,401 strikes reported in 2013. For 1990–2014, 156,114 strikes were reported. Birds were involved in 96.9 percent of the reported strikes, terrestrial mammals in 2.2 percent, bats in 0.8 percent and reptiles in 0.1 percent. Although the number of reported strikes has dramatically increased, the number of reported damaging strikes has actually declined since 2000. Whereas the number of reported strikes increased 127 percent from 6,009 in 2000 to 13,668 in 2014, the number of damaging strikes declined 24 percent from 764 to 581. While there was a 20 percent increase in reported strikes from 2013 to 2014, the number of damaging strikes declined 4 percent from 606 to 581. The decline in damaging strikes has been most pronounced for commercial aircraft in the airport environment (at <1,500 feet above ground level [AGL]). Damaging strikes have not declined for general aviation (GA) aircraft.

From Hedayati, R., Sadighi, M., Bird Strike, 2016:
According to the FAA, there were approximately 11'500 bird strikes in the US in the year 2014.

Bird Strikes in Australia

From Hedayati, R., Sadighi, M., Bird Strike, 2016:

  A significant proportion of all occurrences [...] involve aircraft striking wildlife, especially birds (Bureau, 2009). According to a report (Australian aviation wildlife strike statistics: 2004-2013) providing aviation bird strike and animal strike occurrence data, reported bird strikes have increased from 1085 in 2004 to 1751 in 2011. The Australian aviation industry experienced a reduction in reported bird strikes in 2012 relative to 2011.
  Among the 1568 reported bird strikes [...] in the year 2013, [...]

Bird Strikes in Brazil

From Hedayati, R., Sadighi, M., Bird Strike, 2016:

  Brazil is one of the most suffered countries from bird strike because it has the world’s second largest aircraft fleet as well as the world’s second largest number of bird species. [...]
  The annual number of reported bird strikes has increased from 235 in 1993 to 587 in 2004.

Bird Strikes in the Czech Republic

From Hedayati, R., Sadighi, M., Bird Strike, 2016:

  In the period 1993–1999, the data relating to 165 collisions was entered into the Czech Air Force’s database.

Bird Strikes in France

From Hedayati, R., Sadighi, M., Bird Strike, 2016:

  The annual number of recorded bird-strike events in France exceeds 700, [...] (2008) [...]

Bird Strikes in Iran

From Hedayati, R., Sadighi, M., Bird Strike, 2016:

  Within the years 1996–2011, 271 bird collisions in 32 airports were registered by Iran’s Civil Aviation Organization (CAO).

Bird Strikes in Saudi Arabia

From Kutbi, N., Bird Strike, 2014:

  30 in 2011, 19 in 2012, 37 in 2013

Bird Strikes in the United Kingdom

From Hedayati, R., Sadighi, M., Bird Strike, 2016:

  The total number of reported strikes in the UK has increased from 608 in 1991 to 2365 in 2011: [...]


How does a fixed-pitch propeller changes the blade's angle of attack?

The pitch of the blade is fixed.  But the angle of attack depends on how the blade moves through the air.  That motion is mostly a combination of the forward speed of the airplane and the rotational speed of the blade.

In your graphic, the blade is attached to a plane that is flying up the page.  The blade is sticking out of the page and is being pushed to the right by the turning engine.

At some combination of airplane speed (up the page) and propeller speed to the right, the air would flow exactly along the (fixed) pitch of the blade.

Now, without immediately changing the speed of the plane you increase the RPM.  The blade moves to the right more quickly.  The angle of attack it makes in the air increases.

Put your hand out a car window.  Hold it at a fixed angle relative to the ground (say 15 degrees).  Now, holding the angle constant, move your hand downward rapidly.  The pitch has not changed, but the angle of attack has.  This is the equivalent of increasing RPM.