What is the derivation of 15 and 11.3 used for estimating pivotal altitude?

A possibly surprising result is even airplanes as different as a humble Cessna 152 and a Boeing 747, if able to fly the same speed in the same conditions, would use the same pivotal altitude. The airplane’s velocity and acceleration due to gravity are the only factors in determining pivotal altitude. Detailed derivations by John S. Denker and by ERAUSpecialVFR (13:57 YouTube) are included below.
The exact formula for height above the pylon is
$$h = \frac{v_{air}\cdot v_{gnd}}{g}$$
where $v_{air}$ and $v_{gnd}$ are velocities relative to the air and ground, and $g$ is acceleration due to Earth’s gravity. This shows that the common approximation of squaring groundspeed is the calm-day special case.
Assuming we want to know $h$ in feet, we need to connect the building blocks, namely the units of measure, appropriately. Given that $g$ is 32.17405 ft/s² (that is speeding up by 32-ish feet per second every second), compatible velocity will also be denominated in ft/s. To see why, you can think of the units as canceling out, as in
$$\frac{\frac{\textrm{ft}^2}{\textrm{s}^2}\equiv v^2}{\frac{\textrm{ft}}{\textrm{s}^2}\equiv g} \Rightarrow \frac{\textrm{ft}^2}{\textrm{s}^2} \cdot \frac{\textrm{s}^2}{\textrm{ft}} \Rightarrow \textrm{ft}$$
At least in the airplanes I fly, the airspeed indicator displays knots or miles per hour. The conversion factor from knots to feet per second is $\frac{6{,}076}{3{,}600}$ because there are 6,076 feet in a nautical mile and 3,600 seconds per hour. For statue miles to feet per second, the factor is $\frac{5{,}280}{3{,}600}$. Remember that the formula for pivotal altitude has two velocity factors, so we must square the conversion factor.
$$d_{mph} = 32.17405\ \textrm{ft}/\textrm{s}^2 \cdot \Biggl(\frac{3{,}600\ \textrm{s/hr}}{5{,}280\ \textrm{ft/SM}}\Biggr)^2 \approx 14.9569\ \textrm{mph}^2/\textrm{ft}$$
and
$$d_{kts} = 32.17405\ \textrm{ft}/\textrm{s}^2 \cdot \Biggl(\frac{3{,}600\ \textrm{s/hr}}{6{,}076\ \textrm{ft/NM}}\Biggr)^2 \approx 11.2947\ \textrm{knots}^2/\textrm{ft}$$
Then performing the dimensional analysis to see that the units of measure fit in the knots case, for example:
$$\frac{\textrm{NM}^2}{\textrm{hr}^2} \cdot \frac{\frac{\textrm{ft}^2}{\textrm{NM}^2}}{\frac{\textrm{s}^2}{\textrm{hr}^2}} \cdot \frac{\textrm{s}^2}{\textrm{ft}} \Rightarrow \textrm{ft}$$
That is, the squared airspeed converted to $\frac{\textrm{ft}^2}{\textrm{s}^2}$ divided by the acceleration due to gravity yields a quantity in feet.
Thinking of the magic numbers in the denominator may show more clearly what’s happening. In the case of knots, $\frac{1}{11.3}$ is around 0.0885 feet per knots squared. This means approximately the same as 9 feet per knots gained or lost, per 100 knots (because 9 ≈ 0.0885 × 100). Likewise for statute miles, the pivotal altitude changes by about 7 feet per mph airspeed change, per 100 mph the airplane is traveling. In either case, given two airplanes where one is flying twice as fast as another, a unit of airspeed gained for the faster will have twice the impact on its pivotal altitude as compared with its slower counterpart.

5. Derivation of the Nifty Formula

We wish to derive the nifty formula for the altitude required during a turn on pylon in the presence of wind. We will be using the following quantities:

$R$, horizontal position vector, from pylon to aircraft
$h$, height above the base of the pylon
$V_{Gnd}$, velocity relative to the ground
$V_{Air}$, velocity relative to the air
$W$, wind vector = constant, independent of time
$a$, acceleration vector = derivative of $V_{Gnd}$

or (equivalently) = derivative of $V_{Air}$

$g$, acceleration of gravity

Assumption: We assume constant $\lvert V_{Air}\rvert$ i.e. constant airspeed.

The velocity relative to the air, $V_{Air}$, is perpendicular to $R$. That is, $$V_{Air} \cdot R = 0 \tag{4}\label{eq4}$$ This is required by the rules of the game. The heading is perpendicular to $R$ because the wing is pointing at the pylon, and the airspeed vector is parallel with the heading because we require coordinated flight (zero slip).

The acceleration $a$ is antiparallel to $R$. This is required by the rules of the game, since the wing is pointing at the pylon. That means the horizontal component of lift is pointing at the pylon. Meanwhile, all other forces add up to zero in accordance with the constant-airspeed assumption. Because $a$ is antiparallel to $R$, we have:

$$a \cdot R = −\lvert a\rvert \lvert R\rvert \tag{5}\label{eq5}$$

We will be interested in what happens to all these quantities after some time $\Delta t$ has passed. Time-stepping the equations of motion gives us: $$
\begin{align}
\textrm{new}\ V_{Air} & = \textrm{old}\ V_{Air} + a\Delta t \\
\textrm{new}\ R & = \textrm{old}\ R + V_{Gnd} \Delta t
\end{align} \tag{6}\label{eq6}
$$

Combining equation $\eqref{eq6}$ with equation $\eqref{eq4}$ gives us the time-delayed version of equation $\eqref{eq4}$:$$(V_{Air} + a \Delta t) \cdot (R + V_{Gnd} \Delta t) = 0 \tag{7}\label{eq7}$$

Multiplying out equation $\eqref{eq7}$ gives us: $$0 = V_{Air}\cdot R + a\cdot R\Delta t + V_{Gnd}\cdot V_{Air}\Delta t + a \cdot V_{Gnd}(\Delta t)^2 \tag{8}\label{eq8}$$ The first term vanishes in accordance with equation $\eqref{eq4}$. The second term reduces to $\lvert a\rvert \lvert R\rvert \Delta t$ because of equation $\eqref{eq5}$. The fourth term is negligible in the limit of small $\Delta t$.

Rearranging the remaining parts of equation $\eqref{eq8}$ gives $$\lvert a\rvert = \frac{V_{Air} \cdot V_{Gnd}}{\lvert R\rvert} \tag{9}\label{eq9}$$ This tells us the magnitude of the acceleration. The direction is antiparallel to $R$ as mentioned [elsewhere]. So now $a$ is fully determined, since we know its direction and magnitude.

As usual, when the aircraft is properly banked toward the pylon, the geometry of the situation is shown in figure 3 [shown below]. In this geometry, the law of similar triangles tells us $$\lvert a\rvert = \frac{h}{\lvert R\rvert} g \tag{10}\label{eq10}$$

Combining equation $\eqref{eq9}$ and equation $\eqref{eq10}$ gives us the nifty expression for the required height at any point during a turn on a pylon:$$h = \frac{V_{Air} \cdot V_{Gnd}}{g}\tag{11}\label{eq11}$$ You can readily verify that this reduces to the conventional expression for the pivotal altitude in the no-wind case.

Physics of Flight - Pivotal Altitude - Lesson 6 by ERAUSpecialVFR

Figure created with Khan Academy

$\sum F_y = 0 \Rightarrow L \cos\theta = mg$

$\sum F_x = ma_c \Rightarrow L \sin\theta = \frac{mv^2}{R}$ (centripetal force)

$\frac{L\sin\theta}{L\cos\theta} = \frac{\frac{mv^2}{R}}{mg} \Rightarrow \tan\theta = \frac{v^2}{Rg}$

$\tan\theta = \frac{h}{R} = \frac{v^2}{Rg} \Rightarrow h = \frac{v^2}{g}$

$\therefore PA = \frac{GS^2}{g}$

$\begin{aligned}
  PA = \frac{GS^2}{g} &\approx GS^2\cdot\frac{\left[\left(1\frac{\textrm{nm}}{\textrm{hr}}\right)\left(\frac{1.15\ \textrm{sm}}{1\ \textrm{nm}}\right)\left(\frac{5{,}280\ \textrm{ft}}{1\ \textrm{sm}}\right)\left(\frac{1\ \textrm{hr}}{3{,}600\ \textrm{s}}\right)\right]^2}{32.17\ \textrm{ft}/\textrm{s}^2}{} \\
                      &\approx GS^2\cdot\frac{(1.687)^2}{32.17} \approx GS^2\cdot\frac{2.845}{32.17} \approx \frac{GS^2}{11.3}
  \end{aligned}$


As a plane gets slower, why does a certain bank angle make you turn faster?

Rate of turn is dependent on the following two items:

The horizontal component of lift (centripetal force)
The tangential velocity of the aircraft (true airspeed)

The rate or turn is directly proportional to the horizontal component of lift and inversely proportional to the tangential velocity of the aircraft.

For a given angle of bank, the vertical and horizontal components of lift will be the same, regardless of airspeed in level flight.

Consequently the airplane will experience the same centripetal acceleration, regardless of airspeed.

Since the tangential velocity is slower, any kind of centripetal force will produce a greater rate of turn for a slower flying aircraft as opposed to a faster moving aircraft and this can be shown by the centripetal acceleration equation

$$a_c = \frac{v^2}{r}$$

so both slow flying airplane with a true airspeed $v_s = 100$ knots and fast flying airplane with a true airspeed $v_f = 200$ knots experience the same centripetal acceleration.

$$\dfrac{v_s^2}{r_s} = \dfrac{v_f^2}{r_f} = 4\ \dfrac{v_s^2}{r_f}$$

or, $$\dfrac{1}{r_s} = \dfrac{4}{r_f}$$

Consequently  $r_s < r_f$; in this case $r_f = 4\ r_s$

Since the angular velocity is equal to the tangential speed divided by the radius.

$$\omega = v/r$$

the angular speed of the slower aircraft will be greater than the faster aircraft.

$$\omega_s = v_s/r_s$$

and

$$\omega_f = \dfrac{v_f}{r_f} = \dfrac{2 \  v_s}{4 \ r_s} = \frac{1}{2}w_s$$

So our twice as slow airplane turns twice as fast as the faster one does under these conditions.


How can an airplane roll, yaw and pitch up and down without control surfaces?

The wing is split to two halves, each half is mounted on its own axis. By changing each half's angle of incidence (and thus angle of attack) changes the amount of lift generated by the relevant side.

See this video of a scale model.

A scheme of the mechanism


Why would landing the space shuttle on water have been unsurvivable?

The shuttle lands at 220 mph and would break up. This is 40% faster than airliners with twice the energy to dissipate and the shuttle structure is a great deal lighter. The orbiters were designed to go to space, ending each mission of their 100 mission lives by landing on a smooth runway. Airliners are designed for forty to a hundred thousand landings or more and they don't always fare that well in water either.

(Youtube - Ethiopian 961)


Why are Flight Directors turned on so early?

For a jetliner, the 'why early' is to test the auto flight system. Turning on the F/D also turns on the Flight Mode Annunciator (FMA) and displays the armed modes.

So it's an early check that all systems are go.

From a 777 manual, any fault will be indicated on the FMA as it reads above.

Here are the flow checks pertaining to the F/D and FMA during the cockpit setup:


What plane was this hotel room converted from?


Is it possible to estimate airspeed on top and bottom sides of a wing at zero angle of attack?

The short answer is that it is possible, by way of knowing the pressure distribution and applying the Bernoulli equation to relate the pressure and the velocity.

More specifically to your question, I'm not aware of any published correlation between camber and air velocity (nor do I think it'd have much practical application), but you could come up with your own by running a variety of geometries through XFOIL for a given airfoil geometry (maybe a Clark Y of varying camber for a flat-bottomed design) and applying Bernoulli on the calculated pressure distribution for whatever freestream atmospheric conditions and chord length you want.

Another note: You asked specifically about a wing, not an airfoil. A wing will have lots of other effects contributing to variations in velocity over its surface; there is no easy way to account for all of them.


What are the "high performance characteristics" of a Boeing 777?

The gulf region is very hot, something that can reduce aircraft performance. The 777-9 is better able to cope with that (due to the higher thrust from the engines and larger wing area).


It can be done in theory, as can most airplanes if you develop the attachment fittings and the airplane has a reasonably slow takeoff and landing speed.  The Beech 18 has long been used on floats in the bush.

Notwithstanding the fact that it was done once upon a time on a Navion, in the absence of a pre-existing STC, and access to the particular floats covered by it, the costs would be staggering unless you put the airplane into the Experimental category and even there it would be only slightly less than staggering.

I don't see any signs of a float kit that was ever developed for the Navion for Edo or Wipline, and I assume it's a certfied category aircraft, so I'm going with starting from scratch, which means staggering, which means "fuggeddaboudit".

As an ex bush pilot, as far as doing well as a float plane, several comments:

As a thing, in general, low wing float planes suck.  The wings get in the way of docks.

The takeoff and landing speed needs to be reasonably low, ideally below 50 kt.  There is a bit of a hydrodynamic "wall" you hit around that speed while aquaplaning and if you can't lift off before that speed you zoom along seemingly forever building that last few knots, not to mention the concrete like character the water starts to take on.

To have good utility, unless you base it at a lake and only fly to other lakes, the floats should be amphibious, but amphibs on a 4 place airplane leave you with a 2 place airplane (even though you've removed the landing gear).  Straight floats have only a minimal effect on useful load (because credit is taken for the lift generated by the floats plus the removal of the ldg gear), but amphibs are brutal because the weight of landing gear and pumps is ballast.  In the bush you don't see that many working airplanes with amphibs for that reason unless they really need it.

Hull insurance on a straight floatplane is somewhat higher than wheels, but on an amphib, the premium will melt your eyeballs.  Because, maybe sooner or maybe later, just about every single amphib out there will get landed wheels down on water, eventually.

The floats are destabilizing in yaw, and the Navion has a rather smallish rudder/fin, so it will almost certainly need a ventral fin.  Expect to add it to the STC development work.  Only a few sea planes have gotten away with not adding extra fin area.

So, bottom line is, unless you can find an installation STC, and can locate a set of floats covered by the STC, making it just bolt it all together, rig, make a log entry, and fly, it's a gargantuan task that will quickly bring your friend down to earth unless money is no object.


What requirements are needed to fly an approach that requires you to fly over the US/Mexico border?

I had flown my plane (small 4-seater) from Houston to California a few years ago and on the way back, I stopped in El Paso to refuel and sleep for the night.  While in contact with the tower, following whatever vectors they were giving me, I noticed that I was about to cross into Mexico.  It's pretty obvious from the style of buildings and how close they are together that one area is Mexico and the other area is the US, especially at 1000 ft (or less) AGL.  I asked the controller if this was correct since it would put me across the border into Mexico.  I seem to remember him saying something about they had an agreement with Mexico that allowed them to use / control that airspace.


How do contrails compare between piston-powered aircraft and jet aircraft?

As far as the contrails are considered, there is little difference between the ones formed by different aircraft. Contrails form when the ambient air (which is usually cooler) mixes with the hot, humid exhaust. This usually happens at high altitudes.

One difference may be that the different particulate matter (eg. soot) emitted by both the engines may be different. These particulates act as condensation nuclei for the water vapor at high altitudes. From FAA's Aviation Emissions, Impacts & Mitigation A Primer:

  The soot particles at cruise altitudes interact with other chemicals such as sulfuric acid and nitric acid to form small particles that act as nucleating sites for condensation of water vapor present in the upper atmosphere under certain conditions to form larger particles to form condensation trails or contrails, for short.

While I'd venture that the (older) piston engines emitted more of these particulates, the only study i could find online indicates that the particulate emission is similar in case of gas turbine engines and aviation piston engines using unleaded petrol (while significantly higher in case of older, leaded gasoline, as was used during WWII).

Both images from Microphysical and Chemical Properties of Nanoparticles emitted by Flight Engines by Claus Wahl, Theo Rindlisbacher and Lars Hjelmberg

This would mean that the effect of particulate emissions on contrail formation would've been the same. However, there is another factor- altitude. In general, the (modern) jet engines fly much higher than their piston engines counterparts- the contrails you see in WWII bombers are formed by supercharged engines flying at high altitude to escape from AA defenses. Also, as @ymb already noted, the size/shape and number of exhausts also vary between the piston and gas turbine engines.

Though the mechanism of contrail formation is the same in the piston and gas turbine engines, the difference between them lies in their size/shape per engine and their operating envelope.


What is the angle of attack of horizontal stabilizer?

You are right, the horizontal tail of a conventional airplane appears to have a higher incidence, but the actual angle of attack is smaller than that of the wing.

The wing, flying ahead of the tail, produces downwash, so the flow at the tail location has a distinct downward component. The downwash angle can be calculated from the lift coefficient and the geometry of the aircraft: To simplify things, let's assume the wing is just acting on the air with the density $\rho$ flowing with the speed $v$ through a circle with a diameter equal to the span $b$ of the wing. If we just look at this stream tube, the mass flow is $$\frac{dm}{dt} = \frac{b^2}{4}\cdot\pi\cdot\rho\cdot v$$

Lift $L$ is then the impulse change which is caused by the wing and equal to weight. With the downward air speed $v_z$ imparted by the wing, lift is: $$L = \frac{b^2}{4}\cdot\pi\cdot\rho\cdot v\cdot v_z = S\cdot c_L\cdot\frac{v^2}{2}\cdot\rho$$

$S$ is the wing area and $c_L$ the overall lift coefficient. If we now solve for the vertical air speed, we get $$v_z = \frac{S\cdot c_L\cdot\frac{v^2}{2}\cdot\rho}{\frac{b^2}{4}\cdot\pi\cdot\rho\cdot v} = \frac{2\cdot c_L\cdot v}{\pi\cdot AR}$$
with $AR = \frac{b^2}{S}$ the aspect ratio of the wing. Now we can divide the vertical speed by the air speed to calculate the angle by which the air has been deflected by the wing. Let's call it $\alpha_w$: $$\alpha_w = arctan\left(\frac{v_z}{v}\right) = arctan \left(\frac{2\cdot c_L}{\pi\cdot AR}\right)$$
A typical airliner cruise lift coefficient is 0.4, and a typical aspect ratio is around 8: This results in a downwash angle of nearly 2° if the lift distribution over span is elliptical. In reality, it is more triangular-shaped, so the downwash angle is larger near the center of the aircraft. Note that the engine nacelles of the DC-9 and the MD-80 range are tilted 3° up to align them with the local flow.

The resulting angle of attack is lower by those 3°, and if the angle of attack difference between wing and tail is less than that, the tail surface will appear angled upward. To achieve static stability, the tail will have to fly at a slightly lower angle of attack than the wing.


It is just a matter of technology, it turned out that phase 3 are subject to interferences from wireless devises, resulting in disappearance of displayed data.

We have been alerted of this some years ago and as long as several similar equipments are simultaneously  functional, it is probabilistically nearly impossible to loose the parameters on all these equipments simultaneously.

I found something about this on the following website, but may be on Honeywell website you will get more details

https://www.ainonline.com/aviation-news/2014-10-01/faa-orders-replacement-737-and-777-display-units

So the  trouble of interferences is specific to phase 3 DU, phase 3A corrects this effect.


During single-engine taxi, how is the asymmetric power compensated for?

First off, the thrust asymmetry problem is far less pronounced in large jet aircraft as compared with light twin engine propeller driven aircraft.  Secondly, taxi operations generally don’t use very much thrust, with the engines often at idle power during this process, only requiring brief bursts of moderate thrust to get the aircraft moving from standstill.

Taxiing small, light twins can be difficult in an OEI (One Engine Inoperative) scenario, in many cases being almost impossible to turn the airplane sharply toward the good engine.  Sometimes pilots will simply turn the aircraft only towards the dead engine and perform a 270° turn toward the dead engine instead of attempting to turn the airplane toward the good engine, should a turn toward the good engine be required.  Sometimes, as a loss of an engine becomes an emergency situation, a light twin pilot will sometime just shut down on the runway or on a turnoff, then just have the aircraft towed back as opposed to attempting to taxi it with an OEI.

Asymmetric thrust can also be used by light twin aircraft to perform even sharper turns at slow speeds, with the pilot simply advancing the throttle to the engine on the outside of the turn while leaving the throttle on the inside of the turn at idle.  This can also be useful for maintaining directional control while taxiing, taking off and landing in strong crosswind conditions, since it requires less rudder input to correct.


Military paintjobs matte for airshow also?

Matte paint creates drag and reduces the top speed. The sheen of the paint is often adjusted to suit operational conditions. For example during WWII an aircraft being prepared for a special high-speed mission, such as a dangerous reconnaissance flight, might have its matte camouflage waxed over to give it that edge of speed. Many combat jets have routinely been finished in a semi-gloss, as a compromise between the two. Special schemes for airshows do tend to be high gloss.


What are the advantages/disadvantages of diesel/Jet A-1 piston engine?

Advantages

Compression-ignition engines have higher compression ratio which leads to being more efficient. So the aircraft range improves and on longer flights payload capacity may improve as well. Fuel consumption is usually about 30% lower.
The higher efficiency combined with the fact that Jet A-1 fuel is cheaper mean they have lower operating cost. Especially since in Europe the leaded avgas is heavily taxed to discourage it's use for environmental concerns.
They should be a bit more reliable. A diesel engine needs high pressure fuel pump, but apparently there are less problems with those than there are with spark-plugs.
They are somewhat easier to operate, since they don't have separate throttle and mixture controls.
They don't suffer the problems associated with incorrect settings of those controls, namely knocking/detonation and pre-ignition.
Turbo-charging them does not carry the risk of pre-ignition and most of them are turbo-charged, so the performance does not decline as fast with density altitude.
There is lower risk of fire since jet/diesel fuel is less flammable (has higher ignition temperature).
Jet A-1 has much wider availability, especially in the third world, so it's easier to plan for fuel stops on a flight through say, Latin America or Africa

Disadvantages

They are heavier for the same power, because they need to be made from stronger material due to the higher compression ratio and because they need to have larger cylinder volume because of lower maximal rpm. On longer flights the reduction in fuel weight often makes up for the heavier engine.
Turbo-charging comes with specific operating procedures unfamiliar to those used to normally aspirated engines and a slight lag in thrust lever (it's not a throttle) response.
As others mentioned, small airports may not have jet fuel yet. This is probably better in Europe where the pressure to phase out 100LL avgas is stronger. Some engines also use automobile diesel fuel or even either jet or diesel fuel as diesel engines are less picky about what they burn.


Often the overspeed is caused by the airflow forcing the propeller to move faster. It's like braking on the engine while going down a steep hill, even without touching the gas pedal you may speed up and redline the engine. Very problematic if you already overheated your brakes in a 18 wheeler.

If you have a variable pitch prop you can feather it to reduce the effect of the airflow. Or just follow the procedures in the overspeed checklist for the aircraft.


How is it possible for manufacturers to constantly get data from their planes all over the world?

How do makers get data from aircraft in flight
The data is usually transmitted using something like ACARS which is a system used in aircraft to transmit data in flight using underlying radio and satellite communications systems.
The communications infrastructure is typically provided by large multinational companies who specialise in this job. See ARINC, SITA, Inmarsat and so on.
Engine-makers and Aircraft makers often offer pro-active maintenance and support services to airlines, operators and lessors which involve their aircraft transmitting such data to the makers.
For example, Airbus has AIRTHM

Airbus Real Time Health Monitoring (AiRTHM) is an advanced service through which A380 and A350 XWB operators can receive guidance on optimised maintenance and real-time troubleshooting actions. As part of this effort, a dedicated 24/7 team takes advantage of the uplink technology to further investigate and anticipate warnings/fault consequences.
The uplink technology allows real-time remote access to aircraft data parameters via the ACARS digital datalink system, enabling Airbus AiRTHM engineers to deliver maintenance and technical advice both in flight and on the ground.

Boeing have AHM

AHM sutomatically monitors, collects and transmits service levels using ACARS through the installed Aircraft Condition Monitoring System (ACMS)

Note that ACARS is a relatively low-volume data transmission system. Makers have explored other underlying communication systems as a way to transmit more data at lower cost.
How is this data stored
It is true that there is a lot of data but Boeing and Airbus are big businesses and are able to partner with major IT businesses.
For example IBM work with Airbus

“Today’s aircraft can generate up to a half terabyte of data per flight, an unprecedented volume and variety of data seen in few other industries,” said Timothy Wholey, IBM global leader for the aerospace and defense industry in its global business services unit.

Note - not all data has to be transmitted in flight. A lot of data is collected and stored in the plane and only transferred when the aircraft is on the ground.
Makers like Airbus and Boeing inevitably are already very heavy users of IT for aircraft design purposes. For example, Airbus use HP Supercomputing hardware


Why don't FMCs automatically include up-to-date oceanic route definitions?

Much like 'Why can't flight management systems receive instructions directly from the controller?', the answer is it should be coming soon (mid/late 2020's).

    FMCs are pretty clever, and they can (and regularly do) pull down data from the network.

You're right, but the issue is "the network". They do that already off private networks, as opposed to a common public network (Aeronautical Telecommunication Network). ATN is now at the heart of the data-link modernization.

Having the option to access and uplink common flight plans and routes to an aircraft's FMS should become a reality (Boeing):

But as the above 2016 presentation shows (starting from the 'B2 Ground Deployment' slide), some old hurdles are still there. A 1994 Flight International article might shed some light on why it's been taking so long:

  It is increasingly clear is that different regions, operators and manufacturers are going to find their way to the ATN by different routes via different steps, and that is giving rise to a variety of concerns. The most avid proponents of the ATN fear that some entities will become content with incremental communications improvements on the way and lose the desire to see the project through.

  Airlines are reluctant to make the necessary investment until civil-aviation authorities (CAAs) make their intentions clear. In a classic chicken-and-egg paradox, however, the CAAs say that they cannot go ahead until they are certain which equipment the aircraft will carry in future. Exasperated service providers are reduced to pleading with the user community to do something, at least.

ATN has been a dream since at least the early 1990's, but reluctance is the reason. But whether the route is oceanic or not, the pilots are supposed to check the FMS entries whether manually typed in or uplinked.


Would an aviation engineering background be helpful for a Flight Data Monitoring Analyst?

Skybrary's page on Flight Data Monitoring defines Flight Data Analysis:

  Flight Data Analysis is founded on Operational Flight Data Monitoring (OFDM) which in North America has become known as Flight Operations Quality Assurance (FOQA). It is a process which routinely captures and analyses recorder data in order to improve the safety of flight operations.

  Flight Data Analysis. A process of analysing recorded flight data in order to improve the safety of flight operations. (ICAO Annex 6 - Operation of aircraft)

  Operational Flight Data Monitoring (OFDM) is the pro-active use of recorded flight data from routine operations to improve aviation safety.

So, this position would be focused on analyzing data from the flight data recorders to make sure the aircraft are being flown in safe and efficient manner.

Engineering (both in aviation and in general) is concerned with design. While an aviation engineering background would probably provide some useful insights, it normally isn't necessary for a position that is not concerned with designing aircraft or aircraft systems.

It would seem that piloting knowledge would be more necessary here than engineering knowledge. In order to analyze whether flight operations are being conducted safely and efficiently, you first need to know what constitutes safe and efficient flight. Technical knowledge of aircraft systems would certainly be needed, but probably more on a pilot level than an engineer level. Additionally, statistical analysis experience will almost certainly be needed.

As an example, here are the qualifications listed for a Flight Data Management Analyst position that I found in a search:

  Essential skills and qualifications:

  Experience in statistical analysis and preparation of graphical representation of data
  Hold accreditation as an aircraft accident/incident investigator or equivalent
  Hold accreditation as quality auditor or equivalent

  Desirable skills and qualifications:

  Experience as a pilot
  Sound aviation technical knowledge in Flying Operations, or equivalent
  Experience in analysis of flight data, using flight data analysis systems (e.g. ADI, Aerobytes, AirFase)
  Experience in utilisation of flight simulator software to recreate flight events
  Familiarity with current EASA regulatory legislation
  Experience in undertaking investigations


What are the rules in UK law on carrying dangerous goods on drones?

Article 94 of the Air Navigation Order

  (1) A person must not cause or permit any article or animal (whether or not
  attached to a parachute) to be dropped from a small unmanned aircraft so as to
  endanger persons or property.

  (2) The person in charge of a small unmanned aircraft may only fly the aircraft if
  reasonably satisfied that the flight can safely be made.

  (3) The person in charge of a small unmanned aircraft must maintain direct,
  unaided visual contact with the aircraft sufficient to monitor its flight path in
  relation to other aircraft, persons, vehicles, vessels and structures for the
  purpose of avoiding collisions.

  (4) The person in charge of a small unmanned aircraft which has a mass of more
  than 7kg excluding its fuel but including any articles or equipment installed in or
  attached to the aircraft at the commencement of its flight, must not fly the
  aircraft:

  (a) in Class A, C, D or E airspace unless the permission of the appropriate air
  traffic control unit has been obtained;

  (b) within an aerodrome traffic zone during the notified hours of watch of the
  air traffic control unit (if any) at that aerodrome unless the permission of
  any such air traffic control unit has been obtained;
  or

  (c) at a height of more than 400 feet above the surface unless it is flying in
  airspace described in sub-paragraph (a) or (b) and in accordance with the
  requirements for that airspace.

  (5) The person in charge of a small unmanned aircraft must not fly the aircraft for
  the purposes of commercial operations except in accordance with a permission granted by
  the CAA.

So section 3 states you must have direct visual contact and section 5 states that you must get permission from the CAA

    An individual or organisation that would like to conduct regular flights with their drone, however, will probably need to submit an
    operating manual to the CAA for a permanent approval. This will allow
    greater freedom to operate continuously without the need to seek ad
    hoc approvals.

  This type of Permission could be of use to:

  emergency services a local authority that would like to use a drone to
  carry out maintenance inspections of its property As with a Permission
  to carry out a commercial operation, the CAA will need to be assured
  of the competence of the person who will be flying the device. The
  ‘pilot’ therefore will probably need to undergo an assessment process
  with one of the approved National Qualified Entities.

http://www.caa.co.uk/Commercial-industry/Aircraft/Unmanned-aircraft/Unmanned-Aircraft/


I found the following rather surprising statement in a (probably quite old) University of Southamption document

Rolls-Royce has never had a service failure of conventional fan blades in over 40 million hours of operation, and there have been no service failures of wide-chord blades in over 10 million hours of operation (Baldwin 1993).
In one incident, RB211-535E4 engines on a Boeing 757 were struck by a flock of Canada geese near Chicago – some seven birds, each around 3 kg, were ingested.  The wide-chord fan blades withstood the impact, which was some eight times greater than the requirements for certification, and the engine did not have to be shut down in flight.

So far as I know, bodies like the NTSB don't collect statistics on blade failure events.


Why does weather radar not report some precipitation?

The National Weather Service's 148 WSR-88D Doppler radars can detect most precipitation within approximately 90 mi of the radar, and intense rain or snow within approximately 155 mi. However, light rain, light snow, or drizzle from shallow cloud weather systems are not necessarily detected.—wunderground

As Ron Beyer commented, the METAR KEWR 010251Z 03012KT 5SM -DZ BR BKN007 OVC012 14/13 A3025 RMK AO2 SLP243 P0000 60002 T01390133 58001 shows light drizzle.


Do additional passengers impact on weight and balance of a domestic airliner?

You're really asking two questions here

1) What is the procedure (ie when are the calculations made)?

2) Do additional passengers affect the weight?

What is the procedure

As soon as check in closes, the numbers for passengers and bags is finalized - nothing else can be added to the plane, otherwise it could potentially run out of fuel. Passengers can be removed, but the captain must be informed in case it affects balance.

At this point the captain calculates the required information for weight, fuel, and balance. It's done shortly after check in closes as there is a limited window in which to add extra fuel etc - remember that the tanker needs to be long clear before the engines can be started and other departure checklists can be run.

This is done so early because the pilot needs time to prepare the aircraft for departure, he doesn't have time to mess about later on adjusting the numbers, and if he has to re-calculate later it adds a whole extra area where mistakes can be made - especially since later on the pilot is likely to be more distracted. Doing it once is fairly easy, you plug the number of passengers into a set of sums along with temperature and other related factors, and it works fuel load out for you. If you try adding passengers you have to re-calculate this, then work out how much extra to add... it's just a whole bunch of extra things that can go wrong.

Do extra passengers affect the weight/balance of the aircraft

Short answer: yes

Take an A319 as an example aircraft: empty, it weighs 40,000 kg, up to a maximum of around 60,000kg

Now I have no idea what you and your family and bags weigh, but let's produce a range. Please don't be insulted by the range: the airline aren't judging your weight when deciding if you can board late: they have to have a single rule regardless of whether it's a skinny teenager travelling alone or a party of 15 obese people

You're an adult, so you presumably weigh anywhere between 50 and 150kg
You said children but don't state an age, so they could be newborns or adults: weight anywhere between 2kg and 150kg
I don't know how many children you have, but for the sake of argument I'll guess it's between 2 and 5 (as you said "children") - that's somewhere between 4 and 750kg

So your total weight for a single family is anywhere between 54kg and 900kg. Chances are most families are more like 250-300kg (a couple of adults at 60-100kg each, and a couple of kids at 20-40kg), but airlines have to assume worst case, otherwise their check in staff have the impossible job of deciding who's too fat to board late.

So take that worst-case scenario (6 obese people) and add a 7kg carry-on bag each, that's nearly 1000kg of weight which the pilot doesn't know on the plane. Or over 2% of the aircraft's empty weight and nearly 1.5% of the maximum takeoff weight. This is assuming they have no hold bags.

Even if your family only weighs 250kg between you and your bags, that's still nearly 0.5% of the aircraft's empty weight - a not insignificant number.

And finally you have to remember that by carrying the extra 0.5% of weight in people, the aircraft needs some extra fuel. And a bit more fuel to carry that extra fuel, and both of those extra amounts of fuel change the balance of the aircraft.

In most "normal" flights you aren't going to make a huge enough difference to balance to cause a crash, or change the fuel requirement enough to cause an issue, but if the aircraft had to divert, you could be the difference between running out of fuel or not, and in some worst-case circumstances a really big family could upset a small aircraft.


Do aircraft performance figures include corrections for areas with especially strong or weak gravity?

No they don’t. Any variations in gravity are swamped by variations in temperature, pressure, density, winds, runway surface, runway slope, runway conditions (wet?) etc. that all have a major impact on performance.

But it is an interesting question, and I learned something by following the link. Thanks!

I know it does have an impact on navigation for submarines, which use variations in gravitational fields in their inertial nav algorithms.


A decade is not a long time at all.

What the future holds for the next decade is the new aircraft-ATC communication system, CPDLC. All of the focus is on that. Enabling data links between pilots and ATC is a hard prerequisite for any significant autopilot development.

It's very possible and likely that nothing revolutionary will happen in autopilots.
It's possible and likely that something more minor is going to change.

Some believe autopilots will get more sensor and control fusion. Still nowhere near full control. Others believe more manual flying will become standard procedure, to reduce the damage when the electronics fail and reversion to direct law is required.

No one knows that for sure, so it would be pure speculation. What is known is that autopilot development will not be the next decade's primary focus. For any major new system to fly passengers in 10 years, it would have to be in advanced testing stages already.


Why is the stagnation point on the upper surface before the start of circulation?

The illustrations under the time-invariant, inviscid, irrotational and incompressible (potential) description is a bit misleading, in my opinion. In the real world, assuming the airfoil starts from rest (no flow field) and you start accelerating it to some airspeed, viscosity should start generating vorticity as soon as airspeed becomes non-zero. Therefore, the non-lifting flow field would never exist in the first place.

The non-lifting flow field serves better as an illustration of the flow solution using uniform + doublet flows. In this case, there is a unique solution for a uniform flow past a cylinder with radius $R$:

Radial speed: $V_r=V_\infty cos\theta(1-\frac{R^2}{r^2})$
Tangential speed: $V_\theta=-V_\infty sin\theta(1+\frac{R^2}{r^2})$

Since we can conformally transform most airfoil geometries into a cylinder, flow solutions past a cylinder is a generalization to those past airfoils. The above result assumes zero angle of attack. But since cylinder is symmetrical, a non-zero AOA simply rotates the result by that AOA, and that's why you have the rear stagnation point on the upper airfoil surface.

For a lifting flow, we would need to model with uniform + doublet + vortex flows. In this case, a set of solutions can be obtained for a cylinder:

Radial speed: $V_r=V_\infty cos\theta(1-\frac{R^2}{r^2})$
Tangential speed: $V_\theta=-V_\infty sin\theta(1+\frac{R^2}{r^2})-\frac{\Gamma}{2\pi r}$

Notice that there is, at this point, no imposition on what the vortex strength ($\Gamma$) has to be. You can have an infinite number of lifting solutions with an arbitrary value of vortex strength (at the same AOA). I think that's what (b) and (c) of your second set of figures are trying to illustrate. We get around this by specifying the Kutta-Condition and impose the stagnation point at the trailing edge to get a unique solution.

Since the total flow field must have zero circulation, the starting vortex must have a counter-clockwise circulation.


Is a 61.31 solo endorsement a one-time thing, or does it need to be repeated?

You didn't say which certificates and ratings you hold, but since you mention 61.31 I assume you're already a certificated pilot in a non-glider category/class (ASEL?) and you're receiving glider training.

The short answer is that a 61.31 solo endorsement expires only if the instructor added an expiration date as a limitation. Including an expiration date is optional, not required; see the Bennett interpretation:

  The regulations of 14 C.F.R., however, do not prohibit an instructor
  from placing limitations, including an expiration date, in a §
  61.31(d) solo endorsement. See 14 CFR § 61.195(d) (prescribing flight instructor limitations on endorsements).

AC 61-65 is the reference for endorsements, and it has this language for a 61.31 solo endorsement (note the "optional" limitations section at the end):

  A.71 To act as pilot in command of an aircraft in solo operations when the pilot does not hold an appropriate category/class rating: §
  61.31(d)(2).

  I certify that [First name, MI, Last name] has received the training
  as required by § 61.31(d)(2) to serve as a pilot in command in a
  [specific category and class of aircraft]. I have determined that [he
  or she] is prepared to solo that [M/M] aircraft. Limitations:
  [optional].

Therefore, whether your 61.31 solo endorsement expires or not is determined by the wording of the endorsement itself. But as always, even if your endorsement is valid from the FAA's point of view, the glider school/club and their insurance company may have their own, additional requirements before letting you solo.

I don't understand the second part of your question: "my glider solo endorsement is no longer valid because my power license lapsed". FAA certificates never expire so I have no idea what you mean by "lapsed" (maybe this scenario?). In any case, I suspect that it might be better to ask that as another question; if you do, please tell us exactly which certificates and ratings you have.


How can true altitude be calculated from pressure altitude, temperature and altimeter setting?

I would think the OAT in the example is what your on-board thermometer is showing, so at 12,500 ft, not at sea level. ISA is +15°C at sea level, but at 12,500 ft it is -9.8°C, so you are just -10 off ISA. Let's see. 4 ⋅ 12.5 ⋅ (−10) = −500, so the formulas match.

Note though, that this is still just an approximation. The temperature lapse rate might also differ and that would have to be taken into account as well. The more precise equation is also nonlinear.


What is the purpose of the small fins on top of the wing surface of Boeing aircraft?

They are called vortex generators, and their function is to create a small vortex which re-energizes the boundary layer. Here is a better picture which also shows that their leading edge is swept like that of a delta wing:

Vortex generators on a T-45 (picture source)

In essence, they are small wings which each create their own delta wing vortex. This vortex mixes fast-moving air from outside the boundary layer with the air close to the wing surface, which has been slowed down by friction. This helps

at low speed to delay flow separation at high angle of attack
at high speed to avoid an oscillation of the shock position when the supersonic pocket of flow over the wing is decelerated in a shock which can cause local flow separation.

The diagram in your question about "Leading edge vortexing" is very misleading. Air does not flow like shown by those arrows.

An airfoil initially accelerates the air which flows over its top surface and decelerates it again over its rear part. On swept wings, this acceleration-deceleration only affects the orthogonal speed component, so the speed component in span direction remains unaffected. This is the reason for the higher Mach capability of swept wings, but also causes the air to flow first inwards and then outwards while transversing the wing's upper surface. The diagram shows no such inward flow, which is wrong.

In addition, friction decelerates the air flowing around a body, such that a layer of decelerated air surrounds each surface of an airplane. The thickness of this boundary layer increases with flow length, and on a swept wing this friction will initially mostly affect the orthogonal flow component. At around mid chord you will find air which has been decelerated mostly in its orthogonal speed component (since this component was so high over the forward part) and now will be subject to more deceleration of the orthogonal component, so that only the spanwise component will be left over the rear part of the boundary layer. Now this boundary layer will only flow off in span direction, such that a massive increase of slow, low-energy air will be collecting towards the tips.

A thick boundary layer will cause early flow separation, so when the angle of attack is increased, the flow at the tips of a backward swept wing will separate first. This will cause lift loss, and since the tips are also the rearward part of the wing, will shift the aerodynamic center forward. This in turn will make the aircraft pitch up, which aggravates the stall condition. If the separation happens asymmetrically, the aircraft will roll in addition to pitching up.

Both vortex generators and wing fences help to reduce this cross flow and delay flow separation on the outer wing at high angle of attack. Vortex generators also help to prevent boundary layer separation past a shock at transsonic speeds when placed close to the leading edge, something a wing fence is incapable of. Therefore, they are more helpful and have displaced wing fences on many swept wings.


What things can a passenger look out for, to indicate an emergency?

Honestly, as a passenger, you're not really qualified to look for problems.  If you're a pilot qualified and with experience in that type then you might see something.

I've had passengers tell my flight attendants that they saw flames coming out of a seam in the engine cowling.  It was actually a section of orange rubbery material that was sticking out and flapping in the breeze.

Ice on the wings depends on the airplane too, you're often going to see some ice on the leading edges in icing conditions, and it's normal.  To know what's not normal, you have to have experience with that specific type.

There is actually one thing you could probably look for.  There are no airplanes that I know of that can safely take off with ice on the top of the wings (behind the leading edges).  That would be a legitimate thing to scream about; however, a pilot that would take off in such a case probably shouldn't be a pilot.

You can certainly ask questions about things you see, but don't phrase it such that you think you found a problem.

Window shades are requested to be open for take off and landing by some operators to allow the flight attendants to quickly assess the situation outside when directing an evacuation.  It has nothing to do with allowing passengers to look for problems.  Not all airlines have this policy either, it's somewhat uncommon, the first thing I do when I sit down at a window in the back is close the window, and it's rare that I'm asked to open it.


Does a flight training company need to make a copy of my driver's license?

According to 49 CFR 1552.3 a flight school is required to keep a copy of the documents used to provide proof of citizenship for five years. This is usually a passport or birth certificate. A driver's licenses is not proof of citizenship in the US.

However, a valid photo ID (such as a driver's license) is required in addition to your pilot's license in order to exercise the privileges of the pilot's certificate because the FAA issued pilot's licenses do not have a photo for identification. So a business that is renting an aircraft to you has a legitimate interest in retaining evidence that they are handing over their valuable asset to a licensed pilot, and that you are who you say you are.

They may not be required to keep a copy of your driver's license, but they are also not required to rent you an aircraft or provide flight instruction.


Should a pre-flight inspection spot snakes on a plane?

Given the location of the snake from the photos/video in the article and the height of the wing/engine assembly (as shown below) I think it's entirely possible to miss this critter in preflight.  A visual inspection of the control surfaces is certainly a part of the preflight, but unlike on a small aircraft (say a Piper Cherokee or Cessna 172) you will probably not be getting "up close and personal" with the control surfaces - you would need a ladder to to so, and the sort of in-depth examinations that would require getting up on that ladder would probably normally be performed by maintenance personnel.

A pilot doing a preflight might get up on a ladder if they noticed something amiss (say a snake obviously hanging from the wing), but on a simple pre-filght visual inspection from the ground this unfortunate critter could easily be missed - particularly if it was curled up tightly in a small space as snakes are wont to do, and didn't have its body hanging out where it could be seen.


How does an aircraft report crew programming of the FMS to the ground?

The aircraft's Flight Management System (FMS) can be loaded with software that periodically sends position reports and flight tracking data to ground stations via ACARS.  If the particular software in use sends the full flight plan or at least the next few fixes periodically with estimated times, this would expose any changes in the flight plan to the dispatch office.

The incident flight in question had its ACARS turned off at some point and the "12 minute" figure is probably derived from the time between the last ACARS message being received and the radar observed turn off course initiated.   They would not be able to know exactly when the buttons on the FMS were pressed, but they could narrow the time down to a range when information changed between two automated reports sent via ACARS.

Relevant chronology:

01:07 final ACARS transmission
01:19 final voice communication

Interval: 12 minutes.


How do aircraft discern that an ACARS message is being sent to them?

A typical ACARS VHF transmission.

Mode A

Aircraft B-18722

Ack NAK

Block id 2

Flight CI5118 <<< looks like an identifier the receiver can filter on

Label B9

Msg No. L05A

Message /KLAX.TI2/024KLAXA91A1

https://en.wikipedia.org/wiki/ACARS


Why was the production of the Lockheed SR-71 Blackbird halted?

Why did they stop building it?

Because they built 32, and that was as many as was needed at the time. 32 spy planes was plenty for the USAF/CIA to use, so building more would have been a waste. By the time those airframes may have needed to be replaced after 30 years or so, the SR-71 had been withdrawn from service and there was no need to build any more.

I think the question you're really trying to ask, though, is:

Why was it withdrawn from service?

And why wasn't it replaced when it was withdrawn?

The answer to those questions is a bit more complex, but essentially comes down to "Because it wasn't really needed any more."

The SR-71 was designed and built in the 50's and 60's. That means it was designed shortly before the first space flight, and built shortly afterward.

When designed, there was a huge need for a fast, "impossible to shoot down" reconnaissance aircraft. The SR-71 suited that - it could dodge missiles just by outrunning them, and by the time any adversary scrambled a fighter and got to the SR-71's altitude, the SR-71 would be a couple of hundred miles away and possibly even over a different country.

So what happened?

Satellites happened.

Why maintain a fleet of very high maintenance planes and keep them on high alert, then fly them over your rival's airspace? That's expensive, time consuming, difficult, risky, and (quite understandably) tends to upset your rival. It was, in short, an expensive way to annoy Russia and China. Okay sure, it got some reconnaissance too, and did its job (as an aircraft) beautifully, but when times are tense the last thing you need is to antagonise each other.

As an aircraft, then, it was a huge success... but as a geopolitical pawn, and as a military asset? It's a little more questionable. It certainly performed a vital role, but it had negative downsides from doing that.

Fast forward a few years, and we developed reconnaissance satellites with a whole bunch of advantages

With a few of them in the right orbit, you can have a satellite over an interesting part of the world pretty much 24/7. Even without that many, you can pass over an area pretty regularly.
Less obvious. Okay, your rival does not like you launching them - but once in space they're just "there", there's no antagonising "Oh look, an SR-71 flying over us"
They're "fire and forget" for the most part. Once in space, you just use it: you don't need to keep a bunch of pilots and aircraft on the ground ready to fly
It's less obvious what you're looking at, and when... if an SR-71 flies over the base that contains your new secret weapon, you're gonna notice. But when a satellite flies over for the 18th time today? Not so much
No planning and preparation time (which, for an SR-71, was a huge undertaking).  You just start taking pictures, or wait for a satellite to get to the right place, then start taking pictures.

They have disadvantages, too

For 24/7 coverage, you need quite a lot of them, and they aren't cheap
You have to replace them occasionally (and/or boost them into higher orbits)
If you upgrade your camera, it's a lot harder to replace the one on a satellite than an SR-71

But overall, a satellite is a more reliable, less antagonistic way to spy on your rivals. They're not perfect, but you know you've got permanent spying capability with no need to plan your reconnaissance ahead of time.

In short: It wasn't needed anymore.


What technical problems stopped scramjets from being used on hypersonic aircraft?

I'm don't research hypersonic flight, but I bet the primary barriers of hypersonic flight are less technological and more political/economical. After all, we pay money and conduct research in order to solve technological problems.

You would think that developing an engine is primarily a task for aerodynamicists since they can design better intakes, compressors, nozzles, etc. However, materials science will typically limit what an engine manufacturer can actually build as you mentioned in your question. Let's imagine aerodynamicists design can design a scramjet that can reliably run for a thousand cycles, but the engine is useless if the aircraft's skin can't handle the high speeds.

More importantly, who's willing to pay for super-inefficient scramjets? Commercial airliners (consumers) weren't even willing to pay for the supersonic Concorde, so you can easily discount them from buying scramjet-powered aircraft. That leaves the military. In the 60s, the military was willing to pay for speed (see SR-71, XB-70), but then stealth became more attractive than speed and super/hyper-sonic research fell by the wayside.

Now the US, China, and Russia are again funding hypersonics research in part because stealth is losing its advantage. Moreover, some startups (Aerion?) are exploring supersonic business jets for the really rich folks, so you're starting to see their engineers exploring hitherto exotic supersonic tech. However, hypersonic flight will still be beyond the means of an average consumer.

TL;DR: Hypersonic research probably stopped less because of tech problems and more because stealth offered more bang for the military's buck. Now the pendulum is swinging the other way. Military supersonic technology is also making its way into the commercial sector for the uber rich.


Is there a worldwide association for stunt/trick/tournament hang-gliding?

FAI (Fédération Aéronautique Internationale)

  – The World Air Sports Federation, is the world governing body for air
  sports, aeronautics and astronautics world records. Its head office is
  in Lausanne, Switzerland.[3] This includes man-carrying aerospace
  vehicles from balloons to spacecraft, and unmanned aerial vehicles
  (such as model aircraft and UAVs). It was founded on 14 October 1905.

FAI is the international governing body for Acrobatics through its FAI Aerobatics Commission("Commission Internationale de Voltige Aerienne" – CIVA).

For Gliding through FAI Gliding Commission("International Gliding Commission – IGC").

For Hang Gliding and Paragliding through FAI Hang Gliding & Paragliding Commission ("Commission Internationale de Vol Libre – CIVL)


How long does it take to refuel a big jumbo jet?

It depends on a number of factors like:

the aircraft size and variant
the range required
the aircraft load
equipment available
Ground crew proficiency

...among others things.

This figure from the 737 Airport Planning document gives 9 minutes for the fueling time for a Boeing 737-600:

Image from B737 Airplane characteristics for Airport Planning

The following image shows the time taken for refueling a Boeing 747-8 Jumbo to be 44 minutes:

Image from B747-8 Airplane Characteristics for Airport Planning


It certainly seems to exist, at least in the sense that at least one has been built and registered. The Wikipedia article "SyberJet SJ30" contains a picture of one.

The registration number on the aircraft pictured is N7SJ, and the FAA's website says that that aircraft is indeed an SJ30.


What is different between a B737 and B757?

Although the 737 has grown over the years, the 737 and 757 remain in different size classes. Both models can be ETOPS certified, although the 757 is more often used in long flights.

At the time the 757 was introduced (in the 80's), the 737 classic series was current. For the 737-400:

Passengers: 146
Length: 119 feet
Wingspan: 95 feet
Wing area: 1135 sq feet
MTOW: 138,000 lb
Takeoff distance: 8000 feet
Range: 2160 nm
Thrust: 2x 23,500 lbf
Max fuel: 5,311 US gal

The 757 was significantly larger. For the 757-200:

Passengers: 200
Length: 155 feet
Wingspan: 125 feet
Wing area: 1951 sq feet
MTOW: 255,000 lb
Takeoff distance: 6500 feet
Range: 4100 nm
Thrust: 2x 43,500 lbf
Max fuel: 11,489 US gal

The 757 is about 35 feet longer, seats about 50 more passengers, and flies about 2,000 nm further (roughly twice as far). The extra range is due to the larger wingspan and longer fuselage, being able to carry more fuel. For this reason, the 757 is used on longer and busier routes, while the 737 is used on shorter, less busy routes.

In the 90's, both models were updated. The 737 was significantly upgraded, including new wings and a new engine, which increased its efficiency. The 737 NG series eventually included the 737-900ER model, currently the largest 737 model.

Passengers: 180
Length: 138 feet
Wingspan: 117 feet
Wing area: 1341 sq feet
MTOW: 187,700 lb
Takeoff distance: 9843 feet
Range: 3235 nm
Thrust: 2x 28,400 lbf
Max fuel: 7,837 US gal

The 757-300 was also introduced. This was a stretched version of the 757-200.

Passengers: 243
Length: 178 feet
Wingspan: 125 feet
Wing area: 1951 sq feet
MTOW: 272,500 lb
Takeoff distance: 7800 feet
Range: 3595 nm
Thrust: 2x 43,500 lb
Max fuel: 11,489 US gal

Although the more efficiency gains of the new 737 bring the range up to nearly that of the 757, the 757 remains significantly larger.


How do I contact Flight Service while in flight?

For filing and opening VFR flight plans, pushing back your ETA because of a delay, and a few more obscure things which you can find in section 4-1-21 of the AIM you would contact Flight Service (addressed as "region Radio" - e.g. "New York Radio" or "Bridgeport Radio")

The universal flight service frequency is 122.2, and above 5000 feet you should be able to get someone on that frequency, but it's not guaranteed.

If yo can't raise someone on 122.2, or you're below 5000 feet, there are local Flight Service frequencies are listed on VORs as shown below. As a general rule if you can receive the VOR you can talk to Flight Service with the frequencies listed, and using these local frequencies helps avoid congestion on the universal frequency.

(skyvector.com)

Initial calls to Flight Service should take the form:
<Facility Name> Radio, Cessna 12345, 5 northeast of Hampton VOR
(as above for Flight Watch, Who you're talking to ("New York Radio" in the example above), Who you are, and Where you are.)

There's a little catch with Flight Service frequencies: If there is an R after the frequency (as shown for 122.1 here) it is a receive-only frequency. You will talk to flight service on that frequency, but you will listen to the VOR's audio channel to hear Flight Service's responses.
When you call Flight Service using one of these frequencies make sure your nav radio is tuned to the VOR and the voice channel volume is up, and let them know which VOR you're listening to as opposed to your location.
In this example if you were contacting Flight Service on 1221 the call would be New York Radio, Cessna 12345, receiving on Hampton VOR.

For weather (giving PIREPs or asking for a weather report) you will also talk to Flight Service: There used to be a separate service (Flight Watch) and frequency for this, but weather-related tasks were consolidated into the general Flight Service frequency in late 2015.

Radio coverage and contact procedures are identical to what was mentioned above for dealing with flight plan stuff, but you should make it clear you're looking for weather updates (add "requesting enroute weather") or that you want to give a PIREP (add "With a pilot report") so the Flight Service Specialist on the other end of the radio knows what you're looking for.

As weather is generally a localized phenomenon (and weather updates or PIREPs can take some time to relay) it is probably be a good idea to use the local flight service frequencies for weather-relatedrather than the universal 122.2 frequency to avoid congestion there, though I don't believe the FAA or Flight Service has issued any official guidance on this since Flight Watch was consolidated with the rest of Flight Service.


What is different between a Cat IIIA, Cat IIIB, and Cat IIIC ILS approach?

ICAO and FAA CAT III definitions

A CAT III operation is a precision approach at lower than CAT II minima. Sub-categories are listed below.

A category III A approach is a precision instrument approach and landing
with no decision height or a decision height lower than 100ft (30m) and a runway
visual range not less than 700ft (200m).
A category III B approach is a precision approach and landing with no
decision height or a decision height lower than 50ft (15m) and a runway visual
range less than 700ft (200m), but not less than 150ft (50m).
A category III C approach is a precision approach and landing with no
decision height and no runway visual range limitation.

*I've omitted the JAA definitions.

Source Airbus Flight Operations Support documentation.

FAA Reference Material

The below links are to comprehensive FAA publications covering the areas as titled.

FAA AC120-29 for CAT I/II.

FAA AC120-28 for CAT III.

Thanks @Sports Racer for the comment with links to these documents.


In my experience it is not "common" for air carrier aircraft to taxi with an engine shut down.  It does happen of course, but there is generally a specific reason behind that procedure if used.

Reasons may be:

Fuel load is close to the minimum required for the flight at the start of taxi (a variety of reasons for this).
Long line up on the taxiway awaiting takeoff clearance.
Captain discretion to save fuel.

For most Air Carriers, the engines are started using air pressure from an APU (auxiliary power unit) affixed to the fuselage (at the tail of the aircraft). The start procedures are initiated while the aircraft is being pushed back from the gate by a tug.  Shortly after the aircraft is pushed back and generally aligned for taxi both engines (twin engine aircraft in this example) have been started and an "after start" (or similar) checklist has been completed. Besides the engine noise, which is sometimes quite low and hard to hear, the end of the start procedure can be noticed when the lights blink in the cabin as the electrical power generated by the APU is being replaced by the engine driven generators.  Also, there is generally an increased airflow into the cabin as air from the engines is vented to the cabin by the air conditioning system.  Very little air is available during engine start from the APU because the air is being used to start the engines.

Anyway, this is probably a more expansive explanation than necessary for your question (I just wanted to give some context to the process of engine start for air carrier jet aircraft).

If the aircraft is taxied out using a single engine, the crew can either start the remaining engine at some point prior to takeoff using the APU (if left operating) or by cross-bleeding the engine air from the running engine to the engine now being started.

If the aircraft is taxied with one of its engines not started at the gate, the crew has to run an additional checklist during the taxi as and after the engine is started.  Not a big deal, but a bit more workload.

Lastly, there have been occasions where problems have resulted from taxiing with one of the engines not started.  For example, many years ago a B727 (3 engine aircraft) started its takeoff roll with only two engines running because the crew failed to start the third engine.  It crashed on takeoff.  Also, there have been occasions where the aircraft was not configured properly for take off (e.g., engine bleed switches in the wrong position) due to a failure to properly follow/run the appropriate checklist for starting an engine during taxi or configuring the bleed/pressurization system properly for take off.

Again, taxiing with an engine not yet started does happen. But considering how many flights occur every day in the world it would be difficult to say this procedure would be anything close to common.

Just my two-cents


What is the ICAO code and callsign for Amazon Prime planes?

As best I can tell, Amazon Air does not hold its own air carrier certificate; they contract with cargo airlines to operate their flights. Per Wikipedia, those contractors are Air Transport International, ABX Air, and Atlas Air. These operators then use their own callsigns.

For example, the aircraft shown in your first link, N1997A ("Amazon One"), is apparently owned  by Titan Aviation, dry leased to Amazon Air, and then operated by a Titan sister company: Atlas Air. The aircraft bears the legend "Operated by Atlas Air Inc" on the paint job. So for the flight it happens to be flying to Charlotte at this moment, it would be identified as GIANT 3581, "Giant" being the codesign for all of Atlas' operations.

But another aircraft in their fleet, N331AZ, is contracted to Air Transport International, and uses the creative callsign "AIR TRANSPORT."

So they don't have an ICAO code or callsign; the companies they hire to operate their flights do.


When should cross country flights occur in flight training

There is no prescribed threshold to cross that indicates when XC training should start.

I generally wait until after a student's first solo to start talking about cross country work.  The first solo is a massive psychological barrier and once the student realizes that they really can fly a plane by themselves, it gives them confidence to learn new stuff.

That said, you are at a 141 school.  They need to follow their approved training schedule.


Do special procedures exist to limit pilot workload during pilot incapacitation?

Well, as a catch-all there is always FAR 91.3 which says he pilot in command can deviate from any regulation if they deem necessary in time of emergency in order to safely operate and land the aircraft. Obviously there's a reasonable limit to that and you'll be asked to give a report to the FAA on what happened, so be ready to defend your actions.

I can't comment on airline company procedures, but I have to assume there is a plan in place for this scenario since it is so realistically likely to happen at some point. I believe another crew member would be asked to help with simple tasks like reading checklists as you mentioned.


How can someone without a pilot's license arrange an initial test flight for a homebuilt aircraft?

Even licensed, experienced pilots often hire other pilots who have experience in test flying and hopefully time in the same model to perform the initial flights. Expect to pay for the service; test pilots do not do the work to build time. How hard it will be to find someone to do it depends on many factors such as the type of aircraft, the reputation of the design, your location and your willingness to allow the testing to take place at a safe field, the quality of your work, if you worked with an EAA chapter and at least one advisor, the quality of your build logs and photos, the quality of your flight test program docs, etc., etc. The EAA can further advise you on this, the membership fee is well worth it.


What should I expect for an unannounced GA visit for touch-n-gos at San Jose?

I have flown several times to SJC for touch and goes. I have always been on the weekends, and probably in the afternoons. It is a lot of fun, especially because the runways are so long for a small plane. I think I’ve been three times, and each time they have accommodated me on 30L. The wind is almost always favoring the 30 runways, and I don’t remember ever being cleared for 30R.

They will occasionally make you circle briefly before entering the C. They will also sometimes make you extend for a pretty long pattern to the SE if they have a big fella cleared for 30R. All the big commercial jets seem to be sent to 30R, and it is small GA jets that use 30L.

I have only done touch and goes, as I wanted to get out of the way quickly. But I get the impression that the tower is happy to accommodate as long as they’re not too busy. My instructor told me that they sometimes will say ‘no’ if they are busy, especially during the morning push, but I have no experience of that.

Have fun! There’s a beautiful 787 that is often at the terminal, keep an eye out for it!


Which pressure mode of operation has the most stress on aircraft frame

Isobaric mode causes the most stress if you keep the cabin pressure and climb higher and higher. (Because the delta pressure and thus the forces become higher and higher)
That's why at high altitudes the isobaric mode is no longer used and the cabin pressurization switches to constant differential pressure instead, which limits the maximum stress.
And unpressurized, well that is not really stressing the hull at all


It's the airfield identification beacon.

  An aerodrome beacon or rotating beacon is a beacon installed at an
  airport or aerodrome to indicate its location to aircraft pilots at
  night.

  An aerodrome beacon is mounted on top of a towering structure, often a
  control tower, above other buildings of the airport. It produces
  flashes not unlike that of a lighthouse.

  Airport and heliport beacons are designed in such a way to make them
  most effective from one to ten degrees above the horizon; however,
  they can be seen well above and below this peak spread. The beacon may
  be an omnidirectional flashing xenon strobe, or it may be an
  aerobeacon rotating at a constant speed which produces the visual
  effect of flashes at regular intervals. Flashes may be of just a
  single color, or of two alternating colors.


Do I need Customs clearance to fly an N-registered aircraft from Italy to Switzerland?

It's true. You need to take off from a authorised Airport with customs in Italy and land at an airport with customs in Switzerland as your first stop.

Here is all information you need including a list of airports with customs.
https://www.ezv.admin.ch/ezv/en/home/information-private/waren-anmelden/einfuhr-in-die-schweiz/warenanmeldung/grenzueberschreitende-fluege.html


Which language is used to develop new aircrafts' avionic systems AI?

Aviation is a very verbose world. Pilots do checklists. They use standard phraseology. Each part in an aircraft has a written history like an ancient sword. There are two communicating pilots in the airliner.
And the main selling point of Python has always been its extremely low level of verbosity. Python ommitts lots of declarative code other langages require. This makes the programming fast and easy but does not give context to see the errors early. An error that would prevent Eiffel or C++ code from even being built would often pass ok for Python, and the program will crash during the run instead, and maybe not always, and maybe after it passes the testing.
As a result, I am convinced that Python is not a choice for something that costs lives when it fails. Such cases have they own priorities and "working prototype in two days" is not between them. I think the role of Python in serious aviation will be rather limited.


Why would the engine quit when turning on the R magneto after an overhaul?

There's 3 potential problems. Magnetos are very simple in how they operate, and the system basically runs on 3 things that can be easily tested.

Spark plugs, engines can die because of 1 bad spark plug, I've had engines become extremely rough and die within 5-10 seconds when checking R/L because of 1 plug with a piece of lead shorting the electrode.
Magneto itself. I highly suggest against opening up and replacing anything in high-time magnetos in the field for multiple reasons. In case of Slicks, the magneto components are designed to wear at an even rate i.e replacing point contacts or a capacitor is not a wise decision for maintenance or for cost-effectiveness over time. An overhauled 4300 series magneto is ~600 dollars, the labor and parts for internal parts reaches that quickly for a substandard magneto as the finished product. I can't speak as much on Bendix but magnetos are a mix of old, complicated, and mechanical that means high wear and high chance for improper reassembly. In this case I assume your O-360 is running 437X Slicks.
Wiring in the ignition switch. You cannot improperly wire a magneto(as far as the operation of the magneto is concerned on a 360, any absence of wires won't stop the operation), and personally this is the least likely of the 3 especially if you didn't touch the ignition. Improper wiring of the backend or improper switch installation could cause this, but again I would highly advise checking the 2 before.

I know this is long past a point of help but I think it helps to explain for anyone else interested


Why are European low-cost carriers not running long haul flights to destinations like the USA, Asia, or the Middle East?

Some are, Norwegian Air runs a flight from Stewart airport in New York to Dublin Ireland and back.

One the benefits that LCC's get is from buying only one airframe for their fleet, which can, depending on where they are based limit their range as many fly A320's or 737's.

The benefit is not within Europe per say but with short, fast turn around, flights that benefit from the general implementation of the hub and spoke system. There are also LCC's domestically here in the USA like Spirit and plenty in Asia as well.


Why does the moment coefficient for angle of attack = 0° not have to be negative?

An airplane achieves steady flight at a given airspeed only if the total pitching moment about its CG is zero. This is achieved with a particular fixed tail angle/elevator angle/canard angle. If the AOA corresponding to the total lift at this airspeed is 0 AOA, then so be it. It's just that for typical airplanes at operational speeds (away from $V_{FE}$ for example), the AOA is typically larger than zero; this means that, for a typical plane, the pitching moment at 0 AOA must be larger than zero at the tail angle, elevator angle, etc. corresponding to the trim speed for static stability.

Why larger than zero? Static stability means that when perturbed from the trim AOA (at which the pitching moment is zero), the resulting pitching moment will return the aircraft back to its original trim without pilot compensation. Take a look at the graph below; note that the moment is zero at AOA=1.5 (i.e. the trim condition).

If the pitching moment at zero AOA is negative (the orange line), then the airplane will diverge from its trim point when perturbed. That's the opposite of static stability.


Is this ferry flight route possible for a B737-800 WL?

(737-800 Payload/Range chart) The winglet version has increased range compared to the chart above, per the airport planning manual.

The variant with the 31.7-tonne fuel capacity has a max ferry range of ~5,500 NM. The biggest leg in your question is ~4,400 NM, it's doable even without any tailwind.

In case the 737 in question has the basic fuel capacity (20.9 tonnes), flying eastbound usually cuts the distance due to flying in tailwind. For example, a distance of 4,400 NM at a true airspeed of 450 knots is reduced to 3,600 NM (air distance) with an average tailwind of 100 knots. And down to 3,300 NM with average tailwind of 150 knots.

  The wind may provide a head- or tailwind component, which in turn will increase or decrease the fuel consumption by increasing or decreasing the air distance to be flown.— Wikipedia

It could be down to choosing the best day to fly with the best jet streams.


What is the speed record for the Boeing 747 and Airbus A380?

The published Maximum Operating Mach number (MMO) for the B747 is Mach 0.92 but it can sometimes be exceeded accidentally due to aircraft upset. It has been reported that Mach 0.99 was attained during a Boeing test flight in a slight nose down attitude.

The A380 has a slower MMO of Mach 0.89

The actual true airspeed of a Mach number will depend on the temperature and altitude but at 35,000 feet Mach 0.92 would be about 530 Knots. (610 mph)


What is the FAA's official stance on logging illegal flight time?

There are probably many answers, depending on the specifics of the situation. But at least one of your scenarios has a certain and definite answer.
I don't think that the FAA has ever issued a legal opinion on this topic, and I kind of doubt they would, but we might be able to piece some answer together.
But first let me address a couple of misconceptions you might have about logging time. In the title and first paragraph of your question, you simply ask about logging time, or logging pilot time. At the end, you ask about PIC or solo time. These are all different kinds of time.
You also wonder whether a pilot could log time, or does the FAA consider that flight to not have had a pilot-in-command. Those are totally different things. Logging pilot time, logging PIC time, and BEING PIC of an aircraft are all different things and don't really have much to do with each other. There are situations where you are PIC and cannot log any time. Other situations where you are not PIC and can log PIC time. Still other situations where you are PIC and can log pilot time, but not PIC time.
To determine whether you ARE ACTING as PIC, you need to look at FAR 1.1: a Pilot in Command

Has final authority and responsibility for the operation and safety of the flight;
Has been designated as pilot in command before or during the flight; and
Holds the appropriate category, class, and type rating, if appropriate, for the conduct of the flight.

That's a totally different section from the regulation that instructs you on how to LOG PIC time, which is FAR 61.51(e):

(1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights-
(i) ...when the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated...

In other words, BEING PIC and LOGGING PIC are completely different criteria. And those criteria for logging are that the pilot is rated, not that the pilot is current.
But there is ONE part of 61.51 that does require currency: Let's start with a student who solos after the expiration of their endorsement. FAR 61.51(e)(4) says:

A student pilot may log pilot-in-command time only when the student pilot -
(i) Is the sole occupant of the aircraft or is performing the duties of pilot of command of an airship requiring more than one pilot flight crewmember;
(ii) Has a solo flight endorsement as required under § 61.87 of this part; and
(iii) Is undergoing training for a pilot certificate or rating.

So for certain, that student cannot log PIC time.
But now, notice that this is the only place anywhere in 61.51 where currency is required. They make a point of it for student pilots but it doesn't show up anywhere else. So I would be tempted to say that a private pilot can log a flight legally that you weren't allowed to make due to currency. And about generally breaking the rules, I am tempted to add to your list: "I flew to my local uncontrolled field and made right turns in the pattern instead of left turns in violation of 91.126(b)." Do I still get to log the time, even though I flew the wrong pattern? Or what if I accidentally violated an ATC instruction? I think I still log that time. After all, making mistakes and learning from them is what "aeronautical experience" is all about.
So in that same vein, what if I flew out of currency and filed an ASRS report? What if I flew out of currency and didn't file a report? I think it's all the same; I think that breaking a reg doesn't invalidate the time.
There are some FAA opinions that back me up a little bit. In Walker, the FAA gives an opinion about a non-instrument rated pilot who manipulates the controls of an airplane in IMC. Because that pilot is manipulating the controls of an airplane in which they are rated, they log PIC time according to 61.51(e)(1)(1). In that opinion, the flight is legal because their instrument rated friend is occupying a pilot station and acting as PIC (But the friend doesn't log time, even though they are PIC, because they are not manipulating the flight controls).
Perhaps more importantly for your question, that pilot also logs instrument time according to 61.51(b)(3)(2) because the time was acquired in IMC. So a non-instrument rated pilot CAN log instrument time, without a CFII on board, even though he has no instrument rating.
So I think that in general, inadvertently breaking a reg doesn't affect logging, but that is different from saying that such a flight is a very smart or safe thing to do, and if you do log it, you're admitting to a violation in an official record. Also not smart.


What's the difference between fog, fog banks, and fog patches?

Thanks to mins's link, the Australian Government Bureau of Meteorology explains everything in detail. To summarise the particular part I was asking about:

FG on its own means fog (visibility < 1000 m) covers more than half of the horizon
PRFG and BCFG are fog covering less than half of the horizon
PRFG (fog bank) is more extensive than BCFG (fog patches)

Another way of looking at it is like cloud cover descriptors. FG is like BKN or OVC: more than half the horizon is covered. PRFG is SCT, and then BCFG is FEW.

All the above are used when the temperature is above freezing point and the fog reaches more than 2 metres above ground. If the fog is only below 2 metres agl, it's shallow fog MIFG instead. If the temperature is below freezing, so the fog consists of supercooled water droplets, it's freezing fog FZFG.


What is the name of this vintage helicopter trainer?

It is a Flettner Bo102 Helitrainer. There were 18 of these produced which were used by six countries.

Source: Airus Helicopter History

Here are some more pictures

It is also known as the Bölkow Bo 102 (Wikipedia).

From Aviastar.org:

  Rolled out in 1959, this Helicopter Trainer was powered by a 40hp ILO piston engine and had a twenty-one foot counterbalanced fibreglass rotor blade. In all eighteen of these HeliTrainers were built operating throughout Europe, training military helicopter pilots. Although unable to fly, they were ideal for the teaching of hovering techniques and were replaced by dual trainer helicopters.

  The Bo-102 Helitrainer, powered by a 40hp Hirth engine driving a simple one-bladed rotor with a counterweight, was developed in land and water based versions, both of which were semi-captive. This feature allowed the helicopter to rise to a height of 0.6m, turn around a vertical axis and dip at up to 6� but prevented it from flying outside these limits.


Is it incorrect to refer to a C-130 as a jet?

CNN actually called it a jet with four turboprop engines, if you can believe that.

ICAO is probably as universal a source as you will find. They list the C130 as turboprop/turboshaft. Their table of aircraft type designators allows selection of engine types from this list: Jet, Turboprop/turboshaft, electric, piston and rocket. There are no associated definitions.


Are approach and departure procedures based on visual reference points official VFR procedures?

Yes, they are official, this is the KSEA MALL VISUAL RWY 34R/C/L approach plate:

I can't find a "East Channel Departure" but if you know what airport it belongs to, you can find it in the Terminal Procedures publication, either in paper form or online.

They are not VFR procedures, but rather visual IFR procedures. The MALL VISUAL would not be assigned to a VFR flight. Some airports do have special arrival/departure procedures which apply to VFR flights; these can be found in the Airport/Facilities Directory (A/FD) or on a website like http://www.airnav.com/ (for the US anyway).


What is the lump on top of the Boeing 737?

It is the antenna for the inflight wifi system. The Southwest aircraft has a Ku band antenna on the top, allowing it to access the internet through satellites. The United aircraft appears to have a similar system.


Who has the authority between captain and first officer in emergencies?

Authority in the cockpit, especially in emergency, is very important in a principle called Crew Resource Managment, or CRM. A number of incidents similar to your example led to the formulation of this concept to enhance the coordination between the crew. The idea is that all crew members should be working together as effectively as possible to solve the problems at hand.

In emergencies, the crew need to be able to communicate. This means that the first officer should be willing to question the Captain, like they did in your example. They should also be willing to take action if they feel it necessary. However, communicating this action is also important, as evidenced in the crash of Air France 447, where the pilots were commanding different inputs.

Neither of the pilots should be ordering the other to do anything unless absolutely necessary. They need to get the attention of the other pilot, state the problem, say why it's a problem, and suggest a solution to the problem. Then they need to agree on a plan of action, and be clear about who is in control.

In your example, the captain's negative attitude may have prevented the first officer from saying anything more.  A better response from the first officer would have been to say something more along the lines of, "Sir, we are flying towards high terrain, we are not flying high enough to clear it. We need to either climb over it or turn left to avoid it. Do you agree?" This makes it clear to the captain what problem the first officer sees, and is clear about how the first officer thinks they should respond. It also includes a direct question for the captain to answer. Both pilots should be ready to communicate like this if necessary, and should also be making sure that they aren't creating an environment where the other pilot isn't comfortable with doing so. If the first officer still got no response, he should have been willing to take control, and should communicate to the captain that he is doing so, including the previously stated information about what actions he intends to take.


What is this very distinct humming noise coming from the IAE-V2500 engines of the A320 during taxi?

I don't think there's anything particularly special causing that sound, it's just how the engines sound.

Inside the airplane you're heavily insulated from exterior sounds, so you're not going to hear much of the airflow and fan sounds from the engine.  You're mostly hearing engine sound that travels through the airframe itself, the turbines primarily.

Outside, the engine sound is dominated by the airflow and fan noise.


How can I convert a Peruvian pilot's license to one that will let me work in the USA?

Well, first step would be a validation of his PPL, resulting in a US PPL based on the foreign one and only valid with both present. This can be done at an FSDO (Flight Standard District Office) for free. It can be done by mail as well. Also many flight schools experienced with foreign students can arrange it at a fee (usually in the 50 USD range). Going through a flight school may be the fastest way - for a CPL he needs one anyway. (Reference)

A foreign CPL (and everything else but a PPL, so like an FI) cannot be converted or validated. He will have to go through full process as described in 14 CFR 61.123. This needs signing up to a flight school/instructor. So while his hours will be accounted for, he need to do at least an extensive check ride (usually more than one - as procedures may differ) to convince the instructor to be ready for the practical test, as well as going through all knowledge tests required - and fulfil the language requirement as well.

A (good) school may also be the best place to get more in depth information, as this case may hold many individual details to be considered.

I guess the worst part might be to (re-) learn the standard phrases used in the US vs. what is used in his country of origin. 8000 hours means a lot of experience and deep entrenched radio phrases :))


What is the distance between 2 adjacent waypoints?

The distance between waypoints on a procedure or airway can vary tremendously. For waypoins on a high altitude airway, over 100 NM is common. For low altitude Victor airways, less. For an instrument departure or arrival, 10 to 20 miles is common, especially near the terminal area. On an instrument approach, legs are almost always under 10 miles. So the limit for your application depends on what sort of airspace you're modeling.  At 100NM square, that's more nearly the size of a terminal area than an enroute sector, so 10 to 40 miles is probably a reasonable ballpark.

Might be worthwhile to order an actual IFR enroute chart - they're only a few dollars, and then you have a real example of what airspace actually looks like. Or, any of the free flight planning websites can show you essentially the same thing on-line.


Why do fabric skin constructions not show up much in larger single engine piston aircraft?

This answer assumes that "GA" means "little piston planes."

Aluminum (or non-fabric) aircraft tend to "hold up" better against the elements.  I would not store a Stinson 108 outdoors but would not think twice about storing a 172 (or Cirrus) on an open air tiedown.  The fabric covering requires a great deal of care compared to the metal (or composite) skin of most GA planes.

Fabric planes must be re-covered every few decades, more frequently if neglected.  This is a non-trivial operation with a price tag to match.  This typically involves reconditioning the now-exposed structure which adds significant cost.  Re-covering and painting a Cub (small plane), for example, can cost an owner tens of thousands of dollars. Stripping, treating, and painting a "metalized" Cessna 120 (similar to a Cub) is a much easier, faster, and cheaper task.

Another consideration is the availability of aluminum.  Aluminum was declared a strategic material in WW2 and, as a result, a great deal of energy was allocated to increase production.  With the war over and the infrastructure in place to produce a lot of aluminum cheaply, why adhere to an antiquated manufacturing process requiring a painstaking level of detail when lower skilled labor can use cheap aluminum to mass produce high quality planes?

In short, fabric planes typically require more care and attention than their stressed skin cousins.  They also require somewhat specialized and skilled labor to build and maintain.  This generally translates into higher costs for everyone involved.

I'm sure there are technical reasons for the shift away from fabric but I'll let Peter (or another technical expert) comment on those.


Why does the static pressure inside the cockpit vary from outside static pressure?

You're referring to this statement in the Pilots Handbook of Aeronautical Knowledge, Page 7-12:

  Some aircraft are equipped with an alternate static source in the
  flight deck. In the case of a blocked static source, opening the
  alternate static source introduces static pressure from the flight
  deck back into the system. Flight deck static pressure is lower than
  outside static pressure.

The reason for this error with alternate static source is that the air flowing around the airframe creates a slight vacuum inside the airframe, thereby lowering the barometric pressure and generating erroneous readings in the pitot-static system.


Time Tracking: Does Turboshaft count towards Turbine time?

Turbine is turbine.  If you burn fuel to spin a turbine that drives a compressor, it's turbine.

I counted all turboshaft time as "turbine" when reviewing resumes for pilot applicants.  Understanding the theory behind turbine engine operation is what everyone cares about, whether is was a turbo-this or a turbo-that is not as important.

Contact a few insurance brokers just to be sure.  Falcon Insurance, AOPA, TrueCourse just to name a few.


Can I use PVC pipes for the rib on the wings of my homemade airplane?

Yes, of course you can.

However, it's probably not a very good idea.

PVC pipes are pretty strong and light; circular-section PVC pipes have an excellent strength-to-weight ratio.

Being strong and light isn't enough though. Construction materials need to have the appropriate properties (like being strong and light) in the right conditions.

In the case of an aeroplane wing, that includes the conditions that aeroplane wings are subjected to: rapidly-changing stresses, vibration, sustained load, torsion and so on. You need to know: will PVC remain strong under such conditions?

Then presumably, you will need to find various ways of joining your PVC sections to each other and to other materials. How will these joins be made? How will they behave under the conditions an aeroplane wing is subjected to? How will the joining methods affect the properties of the PVC pipes?

Aircraft designers tend towards the conservative; even the most radical of aircraft designers would not be considered daring compared to the radical leaps taken by designers in other fields. That's because the chief reward for brave leaps in aviation is death.

All the same, over its history, aviation has tried all kinds of things (usually, quite carefully). If aviation has successfully used PVC pipes in aircraft construction, there'll be a record of it and a tradition of it. The successful pioneers of PVC-pipe-based aviation will not, however, have embarked on their adventures on the basis of an encouraging Stack Exchange reply.

If you don't already know the answers to the questions I mentioned above, and are not already in possession of reliable information about techniques, tools, practices and theory for working safely with PVC load-bearing structures, I'd prefer to use PVC pipes for plumbing only.