Is there a pressure rise and velocity change across a turbofan fan and stator? I've been looking at the pressure / velocity / temperature diagrams across jet engines. These have really helped me to understand the different roles that the compressor/turbine stator and rotors play, and how they compress and then extract energy from the gas flow. I then started thinking about the fan. I've done some reading on how propellers generate thrust in the same way as wings do, with the high and low pressure areas. My question is, do fans primarily generate thrust similar to propellers (i.e. with the high and low pressure areas), or do they operate more like the rotor and stator set-up, with the interaction of subsequent blades acting like nozzles to increase velocity?

The answer is kind of yes and no.

Actually the thrust is always the force with balances the pressure forces on all the parts of an aero-engine.

This means (clarification in the next paragraph) that both propeller and jet-engine "create" thrust with the pressure and suction side pressure distribution of the blades. The following picture from Rolls-Royce's The Jet Engine illustrates that nicely.

Actually nozzle and turbine create drag, because the pressure forces in them do not point into the direction of flight. (Thought-Experiment: Just imagine the bolts of the nozzle would fail: If the nozzle would create thrust it would stay attached to the engine. But as one can imagine the nozzle would fly away from the aircraft).

The nozzle is needed to control the pressure level of the whole engine in order to allow for the engine-process-cycle to work properly. And because of this link one can use momentum conservation to calculate the thrust based on the inlet and exit momentum (velocity) of the airflow.

Looking at a turbo-fan engine the answer stays the same.
From the turbo machinery point of view: The fan does the same two things every compressor stage does. Two things: adding static pressure and whirl. The whirl is converted into pressure in the guide vanes, downstream of the fan.

From the thrust point of view: The fan-blades create the thrust, the stator-vanes (OGVs) down-stream of the fan-blades create drag. But as with the compressor and the nozzle above, without the OGVs the pressure-ratio of the fan would be lower and so would the fan-thrust.

One additional part is needed: The nozzle of the bypass. The above picture by JAXA nicely illustrates that (at least for modern engine installations) the bypass airflow is guided through a convergent-divergent nozzle.

So to sum up. Yes there is a pressure rise (at least locally) across the rotor and a velocity change as well. But the thrust (and drag) is produced by the pressure forces on blades and vanes (and all other engine parts).
And yes the fan operates very similar to a rotor stator setup of a compressor.
But the vanes in a compressor work like a diffuser, reducing the flow velocity. In order to keep the flow velocity mostly constant the annulus is shaped like a nozzle to balance the increased density.


How to correct for crosswind in VOR holding pattern without wind information? I've heard many articles about crosswind correction in VOR holding pattern. They mainly tell the outbound leg=correction times three things for slow speed aircraft. I notice all of them require wind information in holding pattern. What if somehow under some circumstances the pilot doesn't have the wind information whatsoever in holding pattern? Like the wind may change unexpectedly. Is there any method to maintain precise 4 minutes holding pattern in such condition?

One you are established inbound on the VOR radial note the heading you are flying to maintain that course. The difference between that and the radial is your wind correction angle. Multiply it by 3 and apply it to the outbound course heading.

To do this you don't need to know anything about the wind.  You just need to be able to intercept and track the inbound radial.

You can repeat this every inbound leg so if the winds are changing you can update your correction every 4 minutes and you always know you are on course one of ever four minutes. With the generous obstacle protection area even small errors will not compromise safety.


How does the training for an EASA license from the US compare to that from Europe? My plan is to work as a commercial pilot in Europe. But, I heard that the training in Europe might be more expensive and harder than in the US.

For example, to get your PPL you have to face some 1000 theoretical questions before even getting on the plane.

A friend of mine who got his licenses in the US told me that there are academies that offer EASA licenses but in a more affordable and "inviting" kind of training.

Is applying for EASA licenses in the US really a better option? (Cost and training.)

You definitely do not need to answer any theoretical questions before beginning flight training in Europe. In fact pop down to your nearest airfield, find a flight school, and chances are they will get you in the air (even for a trial flight) as soon as they are able.

Whoever told you that may have been thinking of the examinations you need to pass to get your PPL, and while 1000 questions is probably a high estimate, you need to be able to answer exam questions on a bunch of subjects such as Meterology, Air Law, Human factors and radiotelephony. You do this during your flight training, but again there is none of them you need to pass before you can begin.

I am from the UK, and I learned to fly in California. It was before the EASA licenses (In those days they were JAR licenses) but the idea was the same - I was training in the US for a license that was valid in Europe. I had to do the same training, and take the same exams as if I was in Europe learning  there was no difference.

On the cost, yes it was slightly cheaper per hour in the US however when you factored in getting there, staying in accommodation and food etc I don't think there was really that much in it. It was more an opportunity (excuse!) to take a 4 week holiday and do nothing but fly every day in great weather (Something which in the UK, at least, is hard to get to do).

Fun fact: I did this 11th October 2001. Conversation at LAX with TSA having explained I'm entering the US as a lone male to learn to fly - "Don't worry Mr C, you don't fit the demographic we're currently looking for".


May a student continue a discontinued checkride if the CFI who endorsed them voids that endorsement? The Situation
CFI Charlie endorses Student Sara's logbook for a checkride. Sara begins the checkride but discontinues, and receives a letter of discontinuance. So far so good.
Before Sara can reschedule the rest of the checkride, she and Charlie have a disagreement. Charlie has access to Sara's logbook and voids his endorsement by crosshatching the entire text of the endorsement before giving it back to her.
The questions

Is Charlie's endorsement actually considered void?

Sara has the letter of discontinuance in hand. Can she reschedule and complete the checkride without getting a new endorsement?

The test was discontinued. No reason the DPE would be looking in her logbook as a discontinuance is simply a pause in the testing process. She was eligible to test, she remains eligible to test. If she already told the DPE about this the smart DPE would make a note in her test records explaining what occurred. Once endorsed the applicant is endorsed. If the CFI wants to "revoke" her endorsement I believe it's too late.


How much is a QF-16 worth? Wikipedia lists the prices for F-16 as:

F-16A/B: US\$14.6 million (1998)[4]
F-16C/D: US\$18.8 million (1998)[4]

However, this is clearly outdated, and I suspect that the aircraft in the worst conditions are being used for these conversions.
It would be interesting to see a ballpark figure out the actual worth of these drones, excluding and including the conversion process.

This has a pretty broad range of answers for this, but I assume what you are asking is what a flight ready QF-16 would sell for should it become instantly available on the civilian market.

Well the short answer is whatever someone is willing to pay for it.

The long answer is that aircraft values are based on a large range of variable, including, but not limited to, the value of the airframe, the current time and status of all life limited parts, currency of all required inspections, status of airworthiness directive compliance, avionics, outstanding repairs and overhauls, etc.

Now assuming this QF-16 is an acquired F-16A reclaimed from AMARC, with a reasonable amount of time left on the airframe, engine and all functioning avionics and systems as manufactured in the early 1980s by GD Fort Worth, the jet could easily command 15 million in FY2019 USD.  Now the QF-16 conversion costs vary depending on the contract signed but typically go for about 1.1 million per jet.  Add to that a dealer and/or brokerage fees of 15% sale price, the cost of flight training a reasonable budget might be 50 or so hours at $25,000 per flight hour or 1.25 million, this gives you an out the door price in the neighborhood of 19.6 million - that is if Congress will sell it to you.


Will wind tunnel modelling ever be completely replaced by computer models? With computer-based fluid simulation already being extremely realistic (and likely faster and cheaper than physical wind tunnels), are they, anywhere, completely replacing physical wind tunnels? If not, is this planned anywhere, or even possible?

The thing about computer models is that they are just that; models. They can only approximate the actual behavior we see in the real world.

Computer models are good for trying many different ideas and making predictions. It can be faster to create a new computational test than to make a physical model for a wind tunnel. But very detailed fluid dynamics calculations require large amounts of computing power, and this takes time and money as well.

Wind tunnels can give much more detailed and accurate information, and are useful for validating the results given by the computers. The results don't always match, which means that the computer models must be revised. This is where wind tunnels are still very useful. They can test an entire airplane in actual flow, where computing that detail across the whole aircraft would require long computations.

Although a wind tunnel is also only a model of real conditions, it provides an actual body in actual flow conditions, which means the results can correlate much more closely to the real conditions being tested. Computational analysis is limited by assumptions, the chosen modeling method, and computational power.

Until computing power reaches the point where it can run models that will truly match a wind tunnel's accuracy and detail, there will still be a need to use wind tunnels to provide data.


Have there been any solo flights on airliners? As per subject has anyone flown an airliner (737, A319 etc etc or bigger) solo? (meaning only 1 pilot alone with no passengers?) Tried to google search but did not find any reference. Question applies to any of modern airliners era with and without flight engineer.

In normal operations there are regulations against this sort of thing (as Dave has said).  But there have been a few emergencies where the First Office or the Captain have become incapacitated (due to medical emergencies), and the remaining pilot has declined to ask if there is another pilot on board to help fly the plane.

Here is an example from 2011 of a Ryanair flight having this occur**, I have heard of others but can't find references.  So, admittedly, that may be the only actual occurrence.

So, to finally answer your questions:  Very rarely, in an emergency situation, there can be a single pilot on a commercial airliner.  Granted, there were passengers on board, so I'm not sure it fits your narrow definition of "solo", but it's about as close as it's going to get.

For completeness (though I don't think it counts), there have been a few instances of a single pilot stealing a commercial jetliner.

For example this 727.  There were actually two people involved, one was a mechanic, the other had a private pilots license (hence the pilot was "soloing").  The aircraft has not been seen since...so it's assumed it ended badly, and, for the record, it's also assumed the pilot was coerced (if indeed he was even flying the plane).

There are a couple more incidents, namely this Antonov-26, which was stolen by a mechanic, circled for an hour, then crashed.  And also this ATR-42-320, which was actually stolen by a Captain form Air Botswana.  He circled the airport for a couple of hours demanding to speak to everyone from his girlfriend, to his boss to the President of Botswana.  They were actually arranging to have him speak with the president when he crashed his plane into two other Air Botswana ATR-42-320s that were parked on the ground.  He was the only one killed.

Again, though, I'm not sure if these fit the criteria you are looking for.  But in that last one, at very least, he was the only person on board the aircraft, it was a commercial aircraft and he was in fact a Captain.

But to say all this an irregularity would be an extreme understatement...

** For clarification:  The reason I state this is the only example I could find is because it's the only one where I could find a report where it was specifically stated the remaining pilot had no help.  To quote from the report:

  Once the initial Cabin Crew assistance was complete, the Captain indicated that he did not need assistance in operating the aircraft, although this was suggested in the operator’s procedures for pilot incapacitation. The First Officer took no further part in the operation of the aircraft. No inquiries as to the possible presence on board the aircraft of either medically trained personnel or qualified pilots were made.

All other examples I saw either specifically stated that a new co-pilot was found, or they skipped that detail entirely.

All of that being said, I somehow doubt this is the only case, it's just the only one I could explicitly verify.


Can a supersonic plane use a subsonic wing if the nosecone shock produces subsonic airflow around the wing? A supersonic plane will produce shock waves off the nose cone, as seen below:

These oblique shocks reduce the speed of the air that the wing experiences. If the plane is at a low enough Mach number, the shocks will reduce the speed of the air to below Mach 1. For example, I calculate (with the Taylor-Maccoll equations, I could be wrong) that a Mach 1.5 plane with a nose cone total angle of 25° will produce Mach 0.7 flow following that shock wave.

Assuming the shocks off the body don't significantly alter the Mach number, the wings will experience this lower Mach number if their span isn't too large. The wings are then experiencing a Mach number lower than most commercial jets.

Why, then, do almost all supersonic planes use either a highly swept leading edge (most jet fighters) or a sharp leading edge (like the F-104)?

Normally, the flow speed at the wing is about the same as the speed ahead of the bow shock. Only if the fuselage is still conical and expanding at the wing station would the local flow speed be smaller. In order to be subsonic, you would need an absurdly blunt fuselage at Mach 1.5. But the wing is in a way still subsonic if its leading edge sweep is sufficient.

If you look closely enough, every shock has a subsonic region, but it is normally very small. The size of the subsonic region depends on the flow speed and the bluntness of the body causing the shock. See the diagram below for the parts of a classical oblique shock.

Diagram of an oblique shock and its three areas (picture source)

Supersonic aircraft are pointed at the front end in order to minimize the region of the strong shock, resulting effectively in an attached shock. The steeper the shock angle for a given flow speed, the higher the losses are. Only in hypersonic vehicles are blunt noses used on purpose, but nor for braking but for limiting local heat loads.

Why does the subsonic region disappear so soon? Because the cross section of the body stops to grow in flow direction, and the pressure energy past the strong shock is converted into speed again in expansion waves.

This means that the wings still fly in supersonic flow. If the fuselage has a constant cross section along the wing's chord, the flow speed is even the same as the speed ahead of the shock. Otherwise, the tail shock would have a smaller cone angle, which it does not have; the flow accelerates again in expansion waves when the conical nose changes to the regular fuselage, and again when the fuselage contracts at its end.

Now it makes sense to sweep the wing such that it will fit inside the Mach cone resulting from the inboard wing section. This results in a subsonic orthogonal speed component at the leading edge. The important insight here is that the spanwise speed component of the flow is not affected by the wing, and only the orthogonal component counts. If that component is subsonic, the whole wing behaves like a straight wing in subsonic flow. Note that all supersonic aircraft with a subsonic leading edge use blunt-nosed airfoils, because those create a suction force (PDF!) which reduces drag.

At higher speed sweep needs to be so steep that the problems of swept wings cannot be tolerated any more. Then and only then it makes sense to have a supersonic leading edge which has less sweep than the Mach cone and needs to be sharp in order to minimize drag. Another way to combine high sweep and good subsonic characteristics is to use variable sweep. This was the preferred solution until it was realised that high supersonic speed is rarely used in combat.


Can an air traffic controller refuse to give service to an aircraft based on moral grounds? Today I learned about a Twitter account that tweets arrivals and departures to/from Geneva, of aircraft used by dictators.

I was wondering if an individual air traffic controller could refuse to give service to a given aircraft based on moral grounds, without legal consequences?

Maybe I'm a pacifist controller and I prefer to not handle a military aircraft sending troops somewhere. Or I don't like dictatorships and I don't want them in the country/airport where I operate.

Is there any legislation that could protect such objectors? To narrow a little the question, let's stick with Geneva in particular, or Europe in general.

No.

The purpose of air traffic control is to prevent collisions and expidite and maintain an orderly flow of air traffic. An air traffic controller has no say in who gets to fly and who doesn't. Refusing a certain flight would be something that needs to be done at a political level, and certainly far away from an operational level.

Also remember that, except in special cases, air traffic controllers have no way of knowing who is onboard a certain aircraft. Essentially, all we see is a flight ID and a route. Air traffic controllers are not in contact with passenger lists at any time.

Furthermore, air traffic controllers do not have any physical way of preventing flights from taking place. See this slightly related answer: Can a pilot take off at his own discretion?


Is there a standard for the trip paperwork packages that are used by the airlines? I have noticed that different airlines (like LIDO, Delta, AA, etc.) have different formats for their trip paperwork packages, containing pre-flight information that they give to their pilots.  These packages contain things like their flight plan, NOTAM's, weather, weight & balance, etc. There is some overlap of course, but I was wondering if FAA/EASA has some standard or guideline for generating the package?

For national flights, FAA prefers ICAO flight plan. For international flights, ICAO format must be used, From FAA Flight Planning Information:

  The FAA prefers users to file ICAO format flight plans for all flights. An ICAO format flight plan MUST be used when:

  The flight will enter international airspace, including oceanic airspace controlled by FAA facilities.
  The flight expects routing or separation based on Performance Based Navigation (PBN), e.g. RNAV 1.
  The flight will enter RVSM airspace.
  The flight expects services based on ADS-B.

EASA follows a format similar to ICAO.

The flight plan usually consists of the following:

Aircraft type and identification.
Flight Rules.
Equipment.
Source, destination, departure time and (estimated) arrival time.
Route details.

among other things.

The following image shows the ICAO international flight plan

Image from Form 7233-4 - Pre-Flight Pilot Checklist and International Flight Plan from faa.gov

The following shows the domestic flight plan from FAA. Note that the ICAO format may be followed in domestic flights too.

Image from Form 7233-1 - Flight Plan from faa.gov


Why would a Blue Angels pilot leave their gear down? In a recent Blue Angels airshow, one of the pilots had their landing gear down during the first 5 minutes of the show. What possible reasons would justify leaving the aircraft in this state?

No picture available.

What possible reasons would justify leaving the aircraft in this state?

Because it's part of their show routine:

  Solos Take-off (Blue Angel #5: Dirty Roll on Take-Off; Blue Angel #6: Low Transition to High Performance Climb).

This dirty roll is not easy (it killed a Blue Angel back in 1982 in a Skyhawk during winter training), so it shows off skill and plane capability.

And later four planes fly gear down:

  Diamond Dirty Loop: The diamond flies a loop with all 4 jets in the carrier landing configuration.

The dirty loop formation started back in 1986 to celebrate the 40th anniversary and the new F/A-18:

  On 8 November 1986, the Blue Angels completed their 40th anniversary year during ceremonies unveiling their present aircraft, the McDonnell Douglas F/A-18 Hornet. The power and aerodynamics of the Hornet allows them to perform a slow, high angle of attack "tail sitting" maneuver, and to fly a "dirty" (landing gear down) formation loop.

Dirty is plane-speak for gear and/or flaps out, as opposed to a clean configuration.

Source: pinterest.com


What phenomenon causes the increase of drag with rain? I know that rain generally worsens the aerodynamic propeties of an aircraft.

I'm wondering what processes cause the increase in drag.

I'm mostly interested in General Aviation, thus relatively low speed and low altitudes.

Several things I can imagine, although the effects might be small:

The water in the air makes it heavier, increasing the effective value of the air density, $\rho$
Rain might lower the temperature, again having an effect on $\rho$
Rain drops on the wing might cause earlier transition on the wing, increasing  drag.

I hope somebody can clarify what magnitude these effects have, and if there are any more effects that cause an increase in drag when flying in the rain.

While Peter Kämpf already commented the effects I'll take a look at the numbers. Don't expect this calculations to be exact predictions, rather worst cases to know the magnitude of following effects:

Mass increase due to rain drops
Forces due to drops hitting the wing
Early tripping of the boundary layer

After deducing some equations I'll feed them with the data of two different airplanes.

Mass increase due to rain drops

The dew layer you find on your airplane in the morning can reach a maximum altitude of 0.8 mm. Raindrops, which do not fill the complete wing surface, don't usually exceed 2 mm diameter.Therefore taking an average distributed height of $h_W=1mm$ for the water on the wing should be still a worst-case prediction.

$$m_{Drops}=\rho_{W} \cdot A\cdot h_W$$

$A$ is the projected area of the aircraft on the horizontal plane and $\rho_W$ water density.

Forces due to drops hitting the wing

Normal rainfall intensities are about 5 mm/hour and we already speak about violent rain with precipitation rates beyond 50 mm/hour. But let us take the heaviest rate ever measured: $I_R=38mm/min$.

Drops fall normally with $v_{Drop}=10m/s$.

To simplify the calculation I'll assume vertical rain and that once a drop hits the airplane it sticks to it. In reality you don't accelerate every drop to the airplane speed nor slow its vertical speed down to 0.

i) Drag increase

$$ \Delta D= \rho_{W} \cdot I_R \cdot A \cdot v_{airplane}$$

ii) Lift decrease

$$ \Delta L= \rho_{W} \cdot I_R \cdot A \cdot v_{Drop}$$

To calculate the total drag ($D=C_D\cdot \frac{\rho_{Air}}{2} V^2 \cdot A$) I've used $C_D=0.035$. $V$ is the cruise speed of the aircraft.

Early tripping of the boundary layer

While it's possible to find airfoil polars in rain searching the Internet, I'll first look at a "bugs influence" diagram where you can see the effect of small disturbances at the nose without other effects overlayed. Bugs and raindrops are similar in size, therefore the comparison should be valid.

Source

The polar above shows how the drag can double (100% increase)just because of some small disturbances at the leading edge. Keep in mind that in modern profiles the effect will probably be smaller. The next polar is from a transport aircraft airfoil.

Source

While not so important as in the glider airfoil, the drag coefficient increase (experimental results) is everywhere at least a two-digit percentage.

Airplanes

I've taken two airplanes with really different wing loadings: A1 would be something between the two Solar Impulse models and A2 a single engine four-seater like a Cessna 172. The last three rows give the drag, lift and mass difference as described above as a percentage of its total value.

|                       |            A1 |     A2 |
|-----------------------+---------------+--------|
| Mass m [kg]           |          1600 |   1000 |
| Area A [m^2]          |           210 |     20 |
| Wing loading [kg/m^2] |           7.6 |     50 |
| Cruise speed V [m/s]  |            20 |     58 |
| Lift L [N]            |         15696 |   9810 |
| Drag D [N]            |          1800 |   1323 |
| Drops mass mW [kg]    |           210 |     20 |
| Drag increase dD [N]  |          2660 |    703 |
| Lift decrease dL [N]  |          1330 |    127 |
|-----------------------+---------------+--------|
| dD/D [%]              |           147 |     53 |
| dL/L [%]              |           8.5 |    1.3 |
| mW/m [%]              |            13 |      2 |
|-----------------------+---------------+--------|

SUMMARY

For a normal GA airplane the water mass on the wings and the lift decrease influence due to raindrops hitting the wing even considering the worst possible conditions are low single digit percentages.

While drag increase due to drops hitting the wing is relevant in the extreme case I took here, under normal conditions it should be below single digit percentages too.

On the other hand the drag increase due to the early tripping of the boundary layer is at least a two digit percentage, at high lift coefficients even more.

Airplanes with lower wing loading are more affected with rain precipitation.


Is it practical to fly IFR into Hawthorne Airport (KHHR) in IMC? I am an IFR rated pilot flying 172s and 182s out of Hawthorne Municipal Airport (KHHR) in Los Angeles. I've heard from other pilots that in actual IFR conditions (IMC) it can be difficult to get sequenced for an approach due to the proximity of inbound jet traffic at nearby LAX, perhaps due to separation requirements for IFR aircraft combined with the parallel approaches or the two airports:

What really happens when both airports are landing to the west as is most often the case? My worry is that if I'm returning home on a cloudy day, I might be forced to land at Torrance airport (KTOA) and then Uber it back to my car at Hawthorne.

I've heard from other pilots that they have returned to the area and been told they will have to hold for hours, which obviously makes the Hawthorne LOC approach useless in a practical sense.

Ideally, this question would be best answered by someone who works as an approach controller in the LA basin.

Without pulling up the SOP/LoAs between HHR and LAX and SoCal Tracon, or working at those facilities to see if there's a better option, and just looking at the positions of the airports and their approaches, I'd say for an actual approach into HHR, you'd have to be vectored into the LAX arrival stream and sequenced like that.

From the approach plates, at the HHR Final approach fix you might have enough separation from LAX's 25L/R, vertically, but once you get to the end of the runway there isn't enough separation between the procedures.

Now if HHR tower can see the LAX traffic and apply visual separation that can change things as well, such that they are making sure you don't get too close, to the other final, as long as wake turbulence isn't involved.

Beyond the theoretical, just call the tower or SoCal Tracon and ask, or schedule a visit and ask.


Can I get a restricted ATP based on part 61 training? I graduated from a college with 60 credits that are related to aviation but I got my IR and CPL from out of school which is part 61. Am I still qualified as a candidate who can apply for a 1000hr R-ATP?

Part 61.160 says no:

  (b) A person may apply for an airline transport pilot certificate with
  an airplane category multiengine class rating or an airline transport
  pilot certificate concurrently with an airplane type rating with a
  minimum of 1,000 hours of total time as a pilot if the person:

  (1) Holds a Bachelor’s degree with an aviation major from an
  institution of higher education, as defined in §61.1, that has been
  issued a letter of authorization by the Administrator under §61.169;

  (2) Completes 60 semester credit hours of aviation and
  aviation-related coursework that has been recognized by the
  Administrator as coursework designed to improve and enhance the
  knowledge and skills of a person seeking a career as a professional
  pilot;

  (3) Holds a commercial pilot certificate with an airplane category and
  instrument rating if:

  (i) The required ground training was completed as part of an approved
  part 141 curriculum at the institution of higher education; and

  (ii) The required flight training was completed as part of an approved
  part 141 curriculum at the institution of higher education or at a
  part 141 pilot school that has a training agreement under §141.26 of
  this chapter with the institution of higher education; and

  (4) Presents official transcripts or other documentation acceptable to
  the Administrator from the institution of higher education certifying
  that the graduate has satisfied the requirements in paragraphs (b)(1)
  through (3) of this section.


What, if any, are the rules on ATC politeness? There are plenty of recordings available of ATCs acting impolite, in the linked video, the pilot says he will file a report about the conduct of the ATC.

Would this actually result in any disciplinary action? What are the formal, contractual rules around tone, manners and general politeness when speaking to pilots?

I worked as a controller in the U.S. for many years in the 1970's and 1980's at 3 different busy facilities (twr/artcc/tracon).  There was never a written policy regarding politeness on the radio.  It was, at least for me, common sense to not engage in any extraneous conversation.  Controllers are keenly aware everything that is said on the radio and landlines is being taped.

The few times I was aware that a pilot made a complaint regarding a particular controller, the controller's supervisor would get the tapes, listen to the pertinent section, and then if warranted counsel the controller.

Generally, it was my experience, that when working traffic in a busy facility you would just want to get the job done as professionally as possible and avoid any extra conversation.


What does this plus (cross) sign on this electrical panel mean? I'm looking at a picture of the electrical panel of a Phenom 100 and on it I see a + sign, does anyone have any ideas as to what it's supposed to mean?

(airliners.net)

Above I marked five similar plus signs on the 737 (there are more). Beneath the +'s are the contacts for the backlighting of each panel. If it acts up then pressing on the sign will ground/secure the connection and may solve the issue.

The electroluminescent light-panels are flexible and the ride can be too bumpy sometimes. Better push the right spot than wait for a specialized someone on the ground who knows where each contact is.

Composite based on images from b737.org.uk.


Light business jets - how many are sold each year? This AOPA article  says

https://www.aopa.org/news-and-media/all-news/2018/october/16/hondajets-get-performance-upgrades

  The company is delivering four to five aircraft a month from its Greensboro, North Carolina, factory, the CEO said. In 2017 and the first half of 2018, the HondaJet was the most delivered light jet in the market. All in all, 92 HondaJets are in service with a 99.7-percent dispatch rate, Fujino explained.

So that's 48 to 60 a year.  What other light jets are available for purchase?

For the most recent data available, which is in 2017, GAMA reports that 676 business jets sold worldwide. You can see a breakdown by manufacturer here.

Unfortunately, not all manufacturers detail the models sold. Light business jets typically sell in higher volume, due to their lower cost point. A rough estimate of 60% of sales being light jets would give a rough number of ~405 light business jets sold in 2017. There is no way to ensure this is accurate, but it should give you a ballpark number.


How do pilots manage metric altitude? A minority of the world, specifically Russia and China, uses the metric system in aviation. ATC will tell the pilots to "climb to 900 meters height".

How do pilots of international flights manage this? Do they request the ATC to provide altitude in feet, or do they perform the conversion manually and dial in the altitude in feet to the autopilot?

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

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

Source: aerosavvy.com

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

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


What is supposed to prevent a commercial crew from flying to the wrong airport? Context

Obviously:

Crews are skilled and well trained.
In a crew of two, one can fix others confusion.
There is a flight plan, ATC can inform of a deviation.
GNSS / ILS / VOR / DME frequencies and distances increase situational awareness.

But still:

February 2014: "Planes landed at wrong airports 150 times over 2 decades".
March 2014: Security Alert, NTSB reminded pilots to take care of not landing at the wrong airport.

After having posted this question, I did an additional research, to find NTSB came back to this problem recently, in May 2015:

NTSB releases two recommendations to FAA. One for ATC clearing to land, the other for software detection of wrong location.
Related article: "After 5 planes land at wrong airports, the NTSB has a few words of advice for the FAA".

Relatively few errors, but consequence could be tragic

150 approaches or so wrong are a very small fraction of the many millions of flawless flights, however the NTSB emphasizes the consequences could have been tragic, e.g. if the erroneous airport didn't provide the expected runway length.

Questions

Did the analysis of these incidents show distinct patterns in their occurrence that could be prevented by different procedures or different navigation instruments?
Did the involved pilots, or other professionals think specific improvements had or still have to be made to avoid recurrence?

According to the Wikipedia article on IFR:

  VFR is the most common mode of operation for small craft. However, it is only safe to fly VFR when these outside references can be clearly seen from a sufficient distance; when flying through or above clouds, or in fog, rain, dust or similar low-level weather conditions, these references can be obscured.

So basically, a pilot would land at a wrong airport due to one of the following conditions:

He/She did not have previous experience of landing at the said airport
He/She paid more attention to VFR that IFR (which is usually suggested), and the proximity of the airports confused him/her

  Any aircraft operating under VFR must have the required equipment on board, as described in FAR Part 91.205[5] (which includes some instruments necessary for IFR flight). VFR pilots may use cockpit instruments as secondary aids to navigation and orientation, but are not required to; the view outside of the aircraft is the primary source for keeping the aircraft straight and level (orientation), flying to the intended destination (navigation), and not hitting anything (separation).

This means that a pilor following VFR can get confused, and that would be a completely manual error. To prevent this from happening, he/she should raise a flag with the Control Tower before landing if his IFR shows a different destination, when compared to the place he is intending to land at following VFR.


In the rare event that the U.S. DOD shuts off the GPS, what's the alternative? In the U.S., the Department of Defense along with other Federal Agencies of the Government operates & maintains the GPS.

In the rarest of the events, if for any reason whatsoever, the Government decides to shut off GPS provisioning (even temporarily), what are the consequences/alternatives for the aviation industry?

What percentage of the industry solely relies on The GPS to operate?
What percentage of the industry has enough alternative navigation means to continue operation regardless The GPS?

On a broader spectrum, I'm also curious about the aviation industry's reliance on GNSS and what could happen in cases of global disaster, wars, cyber-wars etc. (all of which are not impossible).

If the GPS is unavailable, it will be quite an impact to the aviation industry.

All airliners in-flight will experience degraded RNAV performance, but they would make it to the destination using VORs, DMEs and ILSs. For general aviation, things are not so lucky. The GPS display provides an excellent situation awareness in small aircrafts; without it, navigation reverts to old school VFR and reading charts. Most pilots will probably make it, but a few may get lost and end up in fuel exhaustion.

For airliners preparing for departure, initiating the INS is time consuming as the GPS coordinate is used as one of the startup parameters. The coordinates of the gates can be looked up in airport charts, some airports also have signs which specify the GPS location; both of these take longer time. Suddenly, pilots flying oceanic routes find out they need more planning for contingencies. Some routes may be changed to fly VOR-to-VOR. Departures around the world are going to be delayed, that is for sure.

Ground Proximity Warning Systems, which use GPS to determine the aircraft's location, are unable to use their terrain database to provide warnings to pilots, although warnings based on radar altimeters should still be available.

Basically, we are thrown back to the 80s or 90s, when GPS was not yet widely adapted. Many of those navigation aids are still in use today, so the industry can still fly, but traffic capacity will be reduced.


Can multiple airfields be in the same airspace? After reading this answer that a restricted airport caused a strange cutout in Class B, I am wondering if it possible that there are multiple airfields in the same airspace?

If yes, then:

Which ATC has most authority
How congestion is handled?

Please note that I am not talking about an airport which is under an outer circular shelf of a Class B or C airport.

When there are several airports close to each other, a single ATC, formally known as Terminal Control Center may service all airports. The airspace boundaries and altitudes assigned to a Terminal Control Center, which vary widely from airport to airport, are based on factors such as traffic flows, neighboring airports and terrain.

London Terminal Control Centre is an example of a large and complex Terminal Control Center. Its service area is up to 20,000 feet and out to 100 nautical miles. It controls:

six London airports
one Royal Air Force station
provides en-route services to other aircraft that entered its airspace

Another example can be found with Berlin-Tegel and Berlin-Schönefeld, which have adjacent control zones that share a common boundary west to east and have an overlaying class C TMA airspace up to FL100. Both airports share the same TMA controller/approach sector:BREMEN RADAR Approach:    119.62

Image Source: www.skyvector.com

FAA is implementing a new airspace system which will increase efficiencies at metropolitan areas with complex air traffic flows. This system, known as Next Generation Air Transportation System is introducing the concept of a metroplex:

  In FAA parlance, metroplex refers to a system of airports in close
  proximity and their shared airspace that serve one or more major
  cities. A metroplex has at least one, but often two or more major
  commercial airports.


What are CAS and EAS used for? What are calibrated airspeed (CAS) and equivalent airspeed (EAS) used for? When would a pilot need to know these?

The different airspeeds:

IAS is indicated airpseed
CAS is calibrated airspeed
EAS is equivalent airspeed
TAS is true airspeed

CAS is IAS corrected for instrumentation and position errors. The errors are most pronounced in slow and high angle-of-attack flight.

IAS figures in aircraft manuals are actually converted from CAS. For ease of use.

How CAS is determined (Wikipedia link).

However, a modern plane with an air data computer (ADC) actually displays CAS, despite being labelled as IAS.

Below 200 knots and 10,000 feet, for all purposes, CAS equals EAS.

As the plane goes faster and higher and compresses the air, the air changes density, an effect known as compressibility that affects the CAS reading.

EAS is computed by the ADC on a modern fast plane, and together with the density altitude, the TAS is then known.

Ground speed and track (from GPS, navaids, and/or INS) together with the TAS allows the FMS to calculate and display the wind speed/direction.

Before ADC's, pilots used charts like those in the answer.

Summary:

In a modern plane, what the pilot actually uses is CAS, despite being labelled IAS. And EAS is used in computing the TAS by the ADC.

For engineers, TAS (actual velocity through the air) is used in lift equations, EAS is used in calculating dynamic pressures on the plane (TAS corrected for air density).

Source used and a must read: Aerospaceweb.org—Types of Airspeed


Are there any mandatory announcements that a captain has to make? Are there any announcements that a captain of an aircraft must make that is reinforced by law or a rule? (This is concerning all countries)

The US does have specific regulations that require the pilot to ensure that passengers are briefed on certain safety issues, although there's no requirement that the pilot must do it personally.

Here are two regulations from the part 91 (all flights) and part 121 (scheduled airline flights) regulations. There may be others.

14 CFR 91.107(a)(2):

  No pilot may cause to be moved on the surface, take off, or land a
  U.S.-registered civil aircraft [...] unless the pilot in command of
  that aircraft ensures that each person on board has been notified to
  fasten his or her safety belt and, if installed, his or her shoulder
  harness.

14 CFR 121.571:

  Each certificate holder operating a passenger-carrying airplane shall
  insure that all passengers are orally briefed by the appropriate
  crewmember as follows [...]

I guess that other countries have similar regulations, but it would be difficult to list them all, so hopefully this example is helpful for you.


Can a holding pattern be in class G airspace? Is separation provided between aircraft holding in class G airspace?
Could there be a holding stack in class G?

By definition, Class G is uncontrolled airspace so the only separation you will receive there comes from using your Mk I eyeballs and good judgment.  A controller is not going to dispatch you to hold in uncontrolled airspace.


How can investigators tell the difference between impact damage and explosion damage when investigating debris from a crash? When reading this article on the debris they found from Flight MH370 they mention a lab in France that is supposed to be able to look at the debris (a flaperon), and figure out if the flight had exploded in mid-air or if it had broken up on impact with the ocean.

This has left me wondering, how would they do that?  How can the folks from that lab tell from an exterior control surface1 that the plane had exploded or broken up on impact?

1 Examples may include elevons, flaperons, elevators, ruddervators, basically anything that helps the plane maneuver and is exterior to the fuselage.

The short answer (to the question in your subject line) is that in an explosion the skin is blown outward, and in impact damage it's (usually) blown inward: In other words you can tell the direction of the force applied by which way the skin around a break/penetration is bent, if you recover the right bits of the aircraft.

The labs start with "Boom = Outie, Crash = Innie", and they can also look at burn patterns (on the paint or as changes in the heat treatment of the metal), chemical residue (if it hasn't all washed away or been contaminated), etc.

In addition to leaving chemical traces or heat-related damage explosions also tend to be physically "messy", so there's usually some physical evidence. Shrapnel punctures through control surfaces are a distinct possibility in an explosion (those punctures generally have a different characteristic than denting and tearing from impact with rocky ground, and again if you get lucky you might even find bits of shrapnel inside the punctured control surface).

The longer answer (to the rest of the question) is that sometimes you can't conclusively tell what happened, particularly from just a single piece of wreckage like a control surface.
In fact quoting from the story you linked there are three different (and valid) theories about what could have caused the damage seen on the particular piece of debris in question:

  The rear damage could have been caused if the airliner had its flaperon down as it went into the ocean, some members of Exner's group wrote in a preliminary assessment after looking at photos and videos of the component.

Entirely plausible: Impacting water at speed could tear chunks out of the trailing edge of a flaperon. It could also break the control surface free of the rest of the wing.

  But the lack of damage to the front makes it more likely the plane was in a high-speed, steep, spiral descent and the part fluttered until it broke off, the group said.

Also plausible: Aerodynamic flutter could break pieces of the flaperon off, or tear the entire control surface from the aircraft (in which case damage may be evident at the points where the flaperon attached to the rest of the wing)

  The lack of damage to the front section "tells me that the component could still have likely been back in its original position inside the wing itself,"

Still plausible but a bit more exotic: The flaperon could have broken off post-impact (and the damage to the trailing edge could have occurred on impact, post-impact, or even pre-impact while the aircraft was still flying).

Note that a lot of what's being put forth in that article (and others) is speculation based on a few photos showing only part of the debris (so far I haven't seen any showing the "bottom" of the debris). A conclusive determination can only be made when the debris is recovered and examined in its entirety.
Attempting to draw conclusions without the full picture can lead to interesting results: The apple is perfect until you see the other side.


if temperature is increased but the volume contained in a area, will an air balloon lift? I understand the archimedes principle as it relates to water, but am having trouble reconciling a thesis related to a hot air balloon.  If theoretically, I could increase the temperature of air contained in a fixed pocket/container, would the increased pressure exerted upward lift the container?  The archimedes principle would argue against the prospect of lifting the container due to the fact that the container remains the same size and therefore displaces the same amount of air outside.  However, I find it difficult to understand why increased upward pressure on the container would not lift the container.  Can you explain?

I case of an hot air balloon, the volume of the balloon remains unchanged when the air is heated. But because the heated air expands, part of it escapes from the balloon since it is not closed (the bottom is open). Therefore the weight of the air inside the balloon is reduced. The hot air in the balloon has a lower density that the cool air around it. Therefore the balloon lifts.

Would a closed balloon of unstretchable fabric be used, then the pressure in the balloon would rise but the volume of the balloon would remain unchanged. Therefore the density of the air inside the balloon and the buoyancy would remain the same and the balloon would not lift off.


Can an aircraft be docked at the gate from the right seat? Not all aircraft can be docked from the right seat, because they have a wheel tiller only on the captain's side, but some can (e.g. the B747-400 of the linked question).

The usual docking system at gates looks like this:

(source)

It seems the azimuth guidance is based on parallax, and is designed for the left seat.

What happens if the pilot in charge of docking the aircraft is seated on the right side? How is the alignment performed without the support of the visual docking system?

Related: Are large passenger aircraft steered during taxi by changing the angle of the front landing gear?

The system you showed may actually be the type that does not depend on the position on the pilot. Edit: The version you have works with a Moiré pattern, and is indeed dependent on which pilot is looking at it.

I dug into the AIS Netherlands information for our country's biggest airport Schiphol (EHAM/AMS). They have a few different systems; the one you link seems to be a lot like the SAFE DOCK system, which uses a Laser Range Finder (LRF) system to identify the position of the aircraft

  Due to the digital display presentation, both pilots get the correct alignment information as well as the closing-rate and stop information.

I'm guessing that this system will become more common to allow for more flexible crew tasks during taxi. Furthermore, this system can detect obstacles, and as such provides extra safety.

The two other systems on EHAM do depend on the seating of the pilot. The effect of the wrong pilot parking the plane is very simple: your plane will be parked off-center with a deviation exactly equal to the spacing between the pilots: your plane will end up such that the co-pilot is sitting where the captain should be. The fact that the AIS does not quote any procedures for this says it all: you just shouldn't do it and wake the captain for a minute to do his duties.

Of course, there are procedures for when the system is not available (emphasis mine):

  The system is operated by an employee of a handling company, who also keeps a safety watch during the docking. The pilot of an arriving aircraft has to be sure that the system is activated. If not, pilots should not enter the aircraft stand and stop before the red boundary line, until the system is activated or a marshaller has signalled clearance to proceed.

The logical conclusion we can draw here is that, if the systems are not available (or, in the case of the question, if the captain is fast asleep), a marshaller will guide the plane in - either way, a marshaller will stand by to oversee the docking and make sure the SAFE DOCK system is living up to its name.

As @reirab helpfully pointed out, the marshaller's job may be nothing more than a simple clearance to enter the gate and let the pilots do their job; they should be perfectly capable of parking an aircraft without the displays. In the aviation world, it's perfectly acceptable to spend a lot of money on these things if they can increase safety; if only due to reduced workload for the pilots.


What callsign would a medical emergency flight use? I see medical emergency helicopters taking off and landing several times a day from the hospital near my office. As I understand from an earlier question, they are probably flying VFR, below controlled airspace and likely without ADS-B.

I would assume, however, that these flights are in touch with the local ATC, and they are certainly announcing their presence on the locally monitored channel(s). Is there a particular set of call signs or other indicators that are used by these flights to indicate to other traffic that, while this flight itself is not in any sort of mayday situation, it needs priority handling and that everyone else needs to get out of the way as lives depend on the speed of this particular flight?

I am asking particularly for the USA/FAA, but would be interested to know if there are differences in other countries around the world.

The variety of callsigns used for medical flights are covered in the AIM 4-2-4:

  b. Air Ambulance Flights.

  Because of the priority afforded air ambulance flights in the ATC system, extreme discretion is necessary when using the term “MEDEVAC.” It is only intended for those missions of an urgent medical nature and to be utilized only for that portion of the flight requiring expeditious handling. When requested by the pilot, necessary notification to expedite ground handling of patients, etc., is provided by ATC; however, when possible, this information should be passed in advance through non−ATC communications systems.

  Civilian air ambulance flights responding to
  medical emergencies (first call to an accident scene,
  carrying patients, organ donors, organs, or other
  urgently needed lifesaving medical material) will be
  expedited by ATC when necessary. When expeditious
  handling is necessary, include the word
  “MEDEVAC” in the flight plan per paragraphs 5−1−8
  and 5−1−9. In radio communications, use the call
  sign“MEDEVAC,” followed by the aircraft registration
  letters/numbers.
  EXAMPLE− MEDEVAC Two Six Four Six.
  Similar provisions have been made for the use
  of “AIR EVAC” and “HOSP” by air ambulance
  flights, except that these flights will receive priority
  handling only when specifically requested.
  Air carrier and air taxi flights responding to
  medical emergencies will also be expedited by ATC
  when necessary. The nature of these medical
  emergency flights usually concerns the transportation
  of urgently needed lifesaving medical materials
  or vital organs. IT IS IMPERATIVE THAT THE
  COMPANY/PILOT DETERMINE, BY THE
  NATURE/URGENCY OF THE SPECIFIC
  MEDICAL CARGO, IF PRIORITY ATC ASSISTANCE
  IS REQUIRED. Pilots must include the word
  “MEDEVAC” in the flight plan per paragraphs 5−1−8
  and 5−1−9, and use the call sign “MEDEVAC,”
  followed by the company name and flight number for
  all transmissions when expeditious handling is
  required. It is important for ATC to be aware of
  “MEDEVAC” status, and it is the pilot’s responsibility
  to ensure that this information is provided to ATC.
  EXAMPLE−
  MEDEVAC Delta Thirty−Seven.


Why commercial planes fly at high altitudes? L= Clq(TAS)^2*S/2
D= Dlq(TAS)^2*S/2

Some say it is due to lower friction drag due to lower density. However if our weight does not change, that means lift does not change as well. So when air density decreases with increasing altitude, TAS increases to maintan required lift force, thus dynamic pressure remains constant. This leads to the fact that drag must not change as well (keeping in mind that Dl and S are constant). What do i miss?

Because while the dynamic pressures of air reacting on the wings at those altitudes remains the same, the speed of the relative winds, and, as a consequence the aircraft’s ground speed is much higher at higher altitudes than near sea level.  This is as a consequence of the air density being much lower at high altitudes than down low.  Cold thin air facilitates true airspeeds 100-300 knots higher than indicated airspeed does.  Therefore per unit of fuel consumed to overcome drag, the airplane travels much farther and consumes less fuel over the course of the flight.

Example:  jet airplane flying at a pressure altitude of 37,000 ft, Outside ambient temperature is -47°C.  If the calibrated airspeed the pilot reads in the cockpit is 300 KCAS, the true airspeed is 575 KTAS.

Add to this that these altitudes do allow the aircraft to access the upper level winds of the jet stream, which range between 30 to over 160 knots on certain days, which can facilitate a healthy tailwind for eastbound flights around the globe.  It is not uncommon for commercial aircraft to log over 650 knots groundspeed in these conditions, further reducing fuel consumption.

As the speed of sound varies proportionally with temperature, compressibility limitations prevent this form being used beyond Mach .8 - Mach .9 due to Cp movement and control buffeting, depending on the aircraft.    There also is a point in the flight envelop where the Stall speed Vs corresponds with the maximum Mach number - see “Coffin Corner” for further details - so this limits the maximum operating altitude based upon outside air temperature as well.  Nonetheless, high subsonic air travel remains one of the most efficient means of moving large numbers of people and cargo quickly around the globe.


Is it incorrect to say that "passenger jets like to cruise at higher altitudes because there's less drag"? I hear it stated quite often that aircraft like to fly high because there's less drag at higher altitudes.
$$ \text{Range} = \frac{V}{g} \frac{1}{\text{SFC}} \frac{L}{D} \ln \left( \frac{W_\text{initial}}{W_\text{final}} \right) \; . $$
Aside from SFC, it seems that none of the components of the range equation are altitude dependent. Lift/Drag should remain constant assuming the lift and drag coefficients remain constant. Therefore, is it incorrect to say that there is a benefit to range flying at a higher altitude due to decreased drag?
Another question is, does the lift/drag ratio of an aircraft increase somehow at  higher altitudes?

There's less drag at the same speed (and other things being equal, aside from altitude).
This is due to lower air density at higher altitude, which linearly affects drag. But just the same, it affects lift! You get less drag, but less lift too. If you want to fly level, you can't afford that: lift must be equal weight.
So what do you do to restore lift? You either fly faster, or increase angle of attack (AoA), or both. Either way, drag will roughly be the same.
Flying faster with the same drag is the benefit. However, sooner or later you'll hit the speed limit. (Most commonly for jets, this will be the Mach limit). From then on, you can only increase AoA.
Changing the AoA affects the L/D ratio. It may increase or decrease, depending on how the wing was designed. There is a certain AoA which will be the 'best'. If the jet was optimised for cruise, it will fly close to that angle.
Does it make any sense to fly even higher, where you have to increase AoA past the best L/D angle? It might, but not much. Primarily because you might squeeze a little better fuel consumption in colder air (that SFC component), so the optimum may be slightly higher. But flying at a higher-than-optimal AoA may be unstable by speed. (Which is manageable, but is another difficulty you don't want).
At some point, you will exhaust either the AoA, getting dangerously close to stall (while, remember, being at the speed limit at the same time - the so called 'coffin corner'), or thrust: it will keep reducing in thinner air, until it becomes lower than drag. That's your ceiling.


Where could I find a MATLAB implementation of TCAS algorithms? Where could I find a MATLAB implementation of TCAS algorithms and simulation?

My research work deals with collision avoidance of a multi-UAV scenario in a small airspace.

MIT LL did indeed build a TCAS model in Simulink/Matlab which was used to validate the algorithms. I doubt they will release it, but it's worth trying to start there.

Otherwise, they did release quite a bit of details in reports. You'll probably end up rebuilding it from their logic.


Could a helicopter fly like a plane this way? Could a wing be added to a helicopter to allow the entire craft to tip 90 degrees forward allowing it to fly faster like a plane using a fixed wing and leaning into the wing for lift?

I understand that there would be major modifications to be made but would there be any benefit?

You've described a tail-sitter aircraft. Instead of a helicopter that tilts sideways to cruise, it's a airplane that can sit on its tail and uses thrust to take off vertically, before transitioning to fixed-wing horizontal flight. This makes more sense since a plane spends more time in cruise than takeoff.

They were first demonstrated by Nazi Germany during WWII. A major benefit over the tiltrotor or tiltwing is that you don't need the bearings that can support the thrust of the engines or lift of the wings. You can also use a single centerline engine. Existing designs use contra-rotating propellers or jet thrust vectoring for anti-torque instead of the helicopter tail rotor.

The idea has been revived recently for UAVs, which don't have the occupant comfort problem:

Aerovironment SkyTote (US Government photo)


Do fighter jets have an auxiliary power unit? Do fighter jets have an auxiliary power unit? If they don't, then how does the propulsion/ignition process start in the engine?

Most current fighters do.
A notable exception is the F-16. The F-16 has a "jet fuel starter" (JFS), which is a small jet turbine started by a bottle of compressed air. Unlike a normal APU, the JFS is linked directly to the main engine, so the only thing you can use it for is to start the main engine.
An APU can also provide backup electrical power. Since the F-16 doesn't have one (and is a fly-by-wire aircraft, which requires electrical power for normal operation), it has an emergency power unit (EPU) instead. The EPU uses a special fuel called H-70, which is 70% hydrazine, and 30% water. Hydrazine (normally used as rocket propellant) doesn't require an external source of oxygen. It carries its own oxygen supply; expose it to iridium and it immediately (well, within a couple milliseconds, anyway) starts to release large quantities of hot gas. This runs a small turbine, which can restore power within about 2 seconds. The main shortcoming is that hydrazine is quite hazardous (though the 30% water content of H-70 renders it substantially less hazardous than pure, anhydrous hydrazine).


With a Pandememic grounding many to their residence.... How to maintain flight hours? No matter your Country, is grounding affecting license requirements(Passenger, Cargo or even Private) and how are the hours being rectified. CNN actually posed a great question in this article and I am also curious to know if this has been addressed CNN: What happens when pilots don't get their flying hours?.
https://www.cnn.com/travel/article/pilots-recency-flying-hours/index.html

Many countries are extending validation periods, but ultimately it's a question that isn't fully answered yet. Right now the focus is on the pandemic - the practical concequences come second.

Chances are it will be a combination of extending legally mandated periods, and common sense by operators.


What are the types of these 3 single-engine aircraft and one Multi engine aircraft? Here are several photos of older aircraft I'd like help in naming. Year, Model, & Manufacturer.
Thanks so much.
Ron

The upper left one looks like a Fairchild PT-19-family monoplane trainer. Production on these started in 1939 and served through the end of the war as a basic trainer. Yours might just be the PT-19B variant, which has a hood over the front cockpit and was used for instrument training:

The upper right one looks like a Vultee BT-13 or BT-15 "Valiant" basic trainer, which were used as Air Force and Navy basic trainers from 1940 to 1944:

The lower left is actually a twin-engine plane, not a single, looks like a variant of the Beechcraft Model 18, or "Twin Beech". These were built beginning around 1937 and continued well into the Vietnam years. Military designations include the C-45 Expeditor, AT-7 Navigator, and AT-11 Kansan, but your specific example appears to be civilian:

The lower right is a North American T-6 or AT-6 Texan. Production on these began in 1933 and they were only retired from all air forces in 1996 (though the last operator, South Africa, only kept them as basic trainers because a military embargo related to its Apartheid policy prevented them buying anything newer):

As far as exact build dates of these aircraft, you might be able to look up the tail numbers of each airplane, but these craft were so common and so varied during their production that exactly when a specific airframe was built is difficult to determine by looking at it. All of these aircraft, in addition, seem to have been "civilianized" after service with the USAAC/USAAF, so their full history may be very hard to trace without their logbooks.


What is the quickest way to get an airship rating? I already have private pilot for single engine land with instrument and commercial ratings.

Since you didn't specify the type of Airship you're looking to get a rating in, I found a Flight Standardization Board (FSB) Report for a Zeppelin, that discusses the training required for that specific Airship.

Here is the relevant time requirements for this particular airship from the document:

5.2 Commercial Airship Pilot
(a) Ab Initio:
Standard duration of training: Approximately 20 months
Maximum duration of training: 24 months
Theoretical training: 300 hours
Practical training: Three months on a ground crew
Minimum of 50 training flight hours
Minimum of 150 supervised flight hours

(b) Students holding a CPL:
Standard duration of training: Approximately 15 months
Maximum duration of training: N/A
Theoretical training: Minimum of 93 hours
Practical training: Three months on a ground crew
Minimum of 40 training flight hours
Minimum of 130 supervised flight hours

(c) Type Rating:
Standard duration of training: Approximately four months
Maximum duration of training: N/A
Theoretical training: Minimum of 49 hours
Practical training: Minimum of 25 training flight hours
Minimum of 100 supervised flight hours

The Commercial Practical Test Standards for Lighter-than-Air can be found on the FAA Website, and you would need to make sure that you had satisfied the following conditions:

  An applicant already holding a commercial pilot certificate who
  applies for an additional category and/or class rating on that
  certificate must:

  hold a commercial pilot certificate;
  have the prescribed aeronautical experience and training required for the category and class rating sought;
  pass an additional knowledge test for the rating sought (unless already rated in airplane, rotorcraft, or airship) since the beginning
  of the 24th month before the month in which he/she takes the practical
  test; and
  obtain an endorsement from an authorized instructor certifying that the applicant has been given flight instruction in the applicable
  AREAS OF OPERATION listed in 14 CFR part 61, section 61.127, for the
  commercial pilot rating sought in preparation for the practical test
  within 60 days preceding the date of application. The statement shall
  also state that the instructor finds the applicant competent to pass
  the practical test, and that the applicant has satisfactory knowledge
  of the subject area(s) in which a deficiency was indicated on the
  knowledge test report.

So you can see the standard duration of training is approximately 15 months. There are some interesting anecdotes in this article from AOPA:

  Pilots interested in getting their pilot certificate with an airship
  rating will have to train while on the job, since there are no schools
  that teach this particular skill, according to Bret Viets, chief pilot
  on the MetLife Snoopy Two blimp.

Veits goes on to say that it took him 66 days. (He started Dec 4, 2007 and took his checkride on Feb 8, 2008). And he thought he did in a pretty short time period. It sounds like he got lucky and ended up having the airship to himself for training for a couple weeks!

Looks like you're on your way with a commercial rating, too:

  The company prefers that applicants have a commercial rating, whether
  it’s on airplanes, helicopters, gliders, or hot air balloons, said
  Viets. “It just makes the transition to airship hourly requirements
  less if someone already has a commercial rating,” he said. “To
  transition to airships is a minimum of 50 hours, but it usually takes
  a little longer than that, like any aircraft rating.”

  If an applicant does not have a commercial rating, he or she will need
  250 hours in airships before getting that commercial airship rating,
  said Viets. “They prefer pilots with 1,200 hours and a CFI
  certificate,” he said.


Why can't flight management systems receive instructions directly from the controller? If an aircraft's flight management system has auto pilot and auto thrust coupling, and it can make changes to the aircraft speed and direction along the entire route without pilot intervention, then why can't controllers just be allowed to make these changes directly without the need to ask the pilot to do it?

Pilots and controllers would still be monitoring the aircraft should things go wrong, but gone would be the days of endless voice instructions like "Flight xyz turn heading 123 climb and maintain...join the localizer for runway xx" "Contact xxxx on 123.xyz"

So many accidents happen due to misheard or unheard voice communication between pilot and controller, along with the pilot's misunderstanding of how flight director modes work.

The FAA should make this a goal, much like adoption of ADS-B.

Short answer: it's coming soon.

For why can't they, the answer is limited data transfers at the moment, which is being worked on.

See: How can shifting to TCP/IP make current aviation systems more delay-tolerant?

Once implemented, it will be like the current CPDLC, where an instruction awaits the crew to press accept, reject, or cancel. A plane like the Boeing 787 already supports simple instructions to be loaded directly into the Mode Control Panel (MCP): the pilot's interface with the autopilot for the different lateral/vertical modes. The 787 is also ready to accept route changes from ATC via the FMS:

Boeing 787 CDU message for accepting a route uplink from ATC. The crew can then press LOAD FMC to view the changes before activating it.

See MCP interface here: What are the differences between ACARS and CPDLC?

When to expect it?

In ICAO's Global Air Navigation Plan, it is expected to be in 'Block 1':

  FANS3/C with CNS integration (via ATN B2) will be
  available providing communication and surveillance
  integration through a connection between the
  FANS and NAV (FMS) equipment. This avionics
  integration typically supports the automatic loading
  in the FMS of complex ATC clearances transmitted
  by data link.

(Emphasis mine.)

Block 1 is between 2018 and 2023. Of course it requires new equipment on airplanes alongside the new ground equipment.

You give an example of an instruction to intercept the ILS. With the avionics integration discussed above, the ATC will receive a downlink from the airplane for its FMS computed performance (e.g., descent performance based on weight and winds). And based on that the flight will receive an uplink with the assigned optimized arrival route to the runway based on 4D navigation (3D + time). The pilot then needs to arrive at each 'checkpoint' at the correct time for traffic separation. This is an example of a "complex ATC clearance".

Above example is still a decade or more in the future (Block 2). The implementation will be in steps. Of those steps is the extension of the arrival management to the en-route area, to be deployed in late 2023 in Europe.


Why is the flight path from Taipei to Tianjin not a straight line? The flight path from Taipei, Taiwan, to Tianjin, China, does not go directly to Tianjin in a straight line.

Instead, it heads directly north, then banks left (west) before heading north again.

(Actual flight CCA188, source: FlightAware)

Possible route: PIANO L3 VIOLA R596 OKATO W13 PINOT B221 OKTUG W506 HGH W554 DOGVI A470 PIX A593 VYK VYK9A/16R (used by virtual crews on simulation networks, source: VATAware.)

Does anyone know why this is?

This will be due to routing and the airways available. Looking at the Enroute Chart for the Taipei FIR, you will notice that there is no direct route northbound, but all routes have a north-east direction to remain clear of restricted area RCR8 (GND - FL370).

(Source: http://eaip.caa.gov.tw)

The flight most likely, as I cannot find the flightplan, departed RCTP - Taipei via the DRAKE1A or DRAKE1B SID, leading to SULEM. Thereafter it continued westbound on the respective airways within China to then join another airway north.

This is consistent with the flightprofile tracked on flightware for EVA730 from RCTP to ZBTJ.

(Source: www.flightaware.com)


Carburetor Heat Required on Carburetor equipped GA aircraft? Is Carburetor Heat Required (by FAA Certification regulations) on Carburetor equipped GA aircraft?
If not, what (if any) certified carburetor-equipped GA aircraft do NOT have Carburetor Heat installed ?

Carb heat is not specifically required by regulation. What is required by the following rule is a means to prevent ice accretion:

  14 CFR 33.35 Fuel and induction system.

  (b) The intake passages of the engine through which air or fuel in
  combination with air passes for combustion purposes must be designed
  and constructed to minimize the danger of ice accretion in those
  passages. The engine must be designed and constructed to permit the
  use of a means for ice prevention.

Carb heat is the most common solution, but alternate solutions may be acceptable.


Why does the Airbus A320 series seem to rock left and right in level flight? I have noticed on all Airbus of the A320 series that I have flown as a passenger (which includes the 319, the 320 and the 321), that whilst in level flight, the aircraft has always a longitudinal axis rocking motion. It is very low but if you focus on the horizon from the window you can actually notice the aircraft rocking left and right. Almost not perceivable but it is actually there! This does not happen on the A330's or A340's

Is there any particular reason for this type of behaviour?

As nobody has answered this in 4 days I'll add this "layman's" input.

I am not a pilot or aeronautically trained, but I understand that essentially all airliners have a dynamic yaw instability aka Dutch Roll and have stabilisers designed to address this. ANY feedback error correction system requires SOME error signal to derive the feedback from and how much error and how it manifests changes with system.

@mins I'm no expert in this area BUT all aircraft are different and you'd be surprised (or should be) if they all behaved the same. The overall combination of a wide range of dynamic forces leads to the end result.

As I recall (probably from Peter R March's very interesting 'The 747 story'  Dutch roll was not a major factor in large aircraft until the larger jets and they lost a prototype with an experienced pilot inexplicably. Subsequent investigations and close calls showed the cause was a dynamic yaw-roll coupling. AFAIR this is caused by the high yaw-induced rolling moment of swept wings and as these are standard fare as speeds rise all large/fast modern airliners have this issue and have a yaw damper to make it unnecessary for the pilot to deal with it.
Without a yaw damper, the vertical tail would need to be much larger to provide enough damping. This costs weight and drag and creates problems of its own due to the location of the tail upwards of the line of symmetry. When the aircraft yaws, the wing creates a rolling moment. This rolling motion causes a drag difference which, together with the directional stability of the tail, swings the aircraft's tail around to the other side, and the process repeats in the opposite direction.

It may be, and I'm 'mentating' this with no proof at all, that they are up against a regulatory barrier and that correcting the problem may lead to them having to do something else expensive. eg early British cars were long stroke not for any technical reason but due to taxation advantages as taxing was based on bore AREA. For a given cc size bore area was reduced by increasing stroke. This limited achievable RPM. Japanese engines had no such limits and I remember our amazement in the early days of Japanese motorcycles at the under-square high revving Japanese motorcycles - which gave them a power per cc rating advantage.

Similarly some America's cup yachts at one stage had their ratings improved by tacking light metal sheeting on their decks. This made NO difference whatsoever.

As an example of stabiliser interaction in another field - many modern cameras have inbuilt motion stabilisers. These need to be turned off when the camera is used on a tripod - or else the compensation system causes the camera to "hunt" about the essentially perfectly stable tripod. I've read of people who had major blur issues through failing to realise this.


Why did most airliners have black noses in the 60's and 70's? Here are a couple of examples:

Under the nose of modern airliners is weather radar that helps the crew to see and avoid hazardous weather conditions. This is required by FAA CFR §121.357 for transport category aircraft. The radar signal would be blocked by the aluminum that makes up the rest of the fuselage, so the radome is made of a non-metallic material, generally a fiberglass composite.

These threads discuss the topic. The last post in the first linked thread suggests that most paint needed lead to prevent fading and/or a zinc-based primer, which would interfere with the radar. Black was one color that did not require these. Modern paint has done away with these metal additives, allowing more color options without interfering with the radar.

The Museum of Flight claims that the black color is only to remind crews to not paint over the radome. Painting over it would affect the radar signals.

According to this thread, the color of the radome affects the operation of the weather radar underneath. They were painted black because it has the lowest reflectivity. Modern radars are able to deal with different colors much better.


Does lack of a curved taxi-line indicate a turn is not permitted? Does the lack of a curved taxiway centerline between two taxiways indicate that a turn is not permitted?
Take for example the complex of taxiway connections at KATL here: 33.636153, -84.421919 (see on google maps). At this intersection, there are several connections between taxiways that don't have a curved line between them. See the attached image for specific examples. Does this indicate that aircraft are not permitted to take this path, whether it's for operational, safety, logistical, or other reasons? If so, are there exceptions to these rules in certain circumstances?

No, lack of a centerline stripe doesn't restrict a controller from assigning that routing, nor does it restrict a pilot from turning there.
The stripe might be omitted because "that" turn wasn't anticipated to be used often, but the stripes (or lack thereof) carry no regulatory authority.


Forces "felt" by pilot, G-meter, inclinometer--are they the aerodynamic forces generated by the aircraft, or the sum of weight+centrifugal force? Consider a pilot sitting at the CG of an aircraft, with instruments also located at the CG of the aircraft.  (Feel free to consider other cases as a bonus, but the core of the question is aimed at this simple case.)

Consider the apparent force "felt" by the pilot, and measured by a traditional-style panel-mounted G-meter, when the aircraft is upside-down at the top of a loop.  Should this force considered to simply be an expression of the wing's lift vector, plus any other aerodynamic force components that the aircraft is generating?  Does gravity make a contribution to this force?  Does "centrifugal force" make a contribution to this force?  Is the force "felt" by the pilot, and the G-meter, due to the combined effects of gravity and "centrifugal force"?  Can more than one of these things be true at the same time?

Consider the apparent force "felt" by the pilot, and determining the deflection of the inclinometer (slip-skid ball), during a coordinated turn, or during an uncoordinated turn.  Is this force simply an expression of the net aerodynamic force generated by the aircraft?  Does gravity make a contribution to this force?  Does "centrifugal force" make a contribution to this force?  Is the force "felt" by the pilot, and the inclinometer, due to the combined effects of gravity and "centrifugal force"?  Can more than one of these things be true at the same time?

Feel free to substitute "acceleration" for "force" in your reading of the question, if you feel it makes it a better question.

Basically this question is seeking to reconcile the view that a pilot only "feels" the aerodynamic force generated by an aircraft, and the view that gravity and / or centrifugal force also play a role in the forces "felt" in flight.  Can these two views be reconciled?  If so, how?  Or is only one of these two views correct?

A thought problem might that better inform the question -- consider an astronaut in orbit.  Is he or she feeling both centrifugal force and gravity?  Or neither?  Or is this purely a manner of convention, i.e. either answer is accurate?

Can more than one of these things be true at the same time?

Yes. It is only a matter of the point of view, or, more precisely, the reference system.

Consider a trivial case first: The aircraft sits on the ground, engine off. The pilot will feel his weight pressing into the seat even in the absence of aerodynamic forces. What he feels is gravity, and the force is the product of his mass and gravitational acceleration.

Now do the same with the aircraft flying in level flight. The forces acting on the pilot are still the same, so it is again gravity what he feels. Only that now the aircraft is not supported by its landing gear and the ground, but by wing lift (and the ground again).

Next step: The pilot flies a dive, followed by a 2g pull-up, meaning that the g-meter reads 2 gs. Again we look at the moment when the aircraft is level, but now it flies on a curved flight path. This adds a centrifugal load of 1g to the 1g of gravity and the pilot feels twice the weight force that he felt before. The nitpickers will now say this is not weight, because weight is the product of mass and gravitational acceleration, but our pilot couldn't care less at the moment. It hurts in his buttocks, that's what counts.

And neither the g-meter nor the pilot could tell gravity apart from centrifugal force – they all feel the same and only the sum of all is felt as a single sensation.

Now switch reference systems and look at the flow around the wing. Speed and angle of attack combine to produce a lift force of twice the weight the aircraft had in level flight. This is pure aerodynamics, no gravity or centrifugal load involved. Strictly speaking, the aerodynamic force on the wing is even a bit higher in order to compensate for the higher tail downforce resulting from trim to overcome pitch damping. Looking at the full aircraft as one object, its total lift force is now twice as high as in level flight.

This force gets transmitted to the pilot seat and the instrument panel and is felt there as a resistance against the acceleration. Depending on your point of view, either the pilot is accelerated into his seat or the seat pushes against the pilot. Actio equals reactio.

Next switch: The same curved flight path, but now at the moment when the aircraft is inverted. Now centrifugal and gravitational acceleration cancel each other, the g-meter reads zero and the pilot feels weightless. In order to do so, the pilots needs to push the stick forward and reduce wing lift to about zero, or wing lift would pull the aircraft down. At this moment we have no aerodynamic contribution to the vertical forces felt by both the pilot and the g-meter.

Now the pilot pushes the stick even more forward so his flight path becomes straight and level again, only with the aircraft in an inverted position. The g-meter now reads -1 g, the force of the harness pressing on the pilot's shoulders is again his weight times gravitational acceleration, but what allows the harness to support the pilot is the lift of the wing the harness is attached to. Change your reference system, and it is again aerodynamics that the pilot feels. Let him wiggle the stick and the change in aerodynamics is immediately felt on his shoulders.


Is it true that airlines won't let pilots drink diet soda? I watched a documentary called Hungry for Change that claimed pilot associations advise avoiding diet soda due to the aspartame sweetener inhibiting motor skills and killing brain cells.

Is this true?

I've never gotten anything to this effect from my airline nor pilot union, and they'd better start stocking cans of unsweetened Snapple if they were to push this, because I don't like coffee & I most certainly don't want to be drinking lots of sugary sodas to get my caffeine fix in the morning!


Tail numbers not starting with N, with domestic US carriers? I'm looking at some of the on-time performance data made public by the US Bureau of Tranport Statistics, e.g. through here. These have the tail numbers of the aircraft used in commercial intra-US flights over the years.
I'm seeing that, occasionally, tail numbers are missing. But in some cases they're actually garbled (e.g. N105@@) - or just perhaps uncommon. Specifically, I'm seeing, among others, tail numbers such as:
89869E
91469E
9149E
A367NW
EI-BWD
HZO
M67153

Can some of these be "legit"? That is, could the above (and similar) strings be actual tail numbers of aircraft which were used in commercial domestic US flights?

Note that we're talking about entries from years between 2001 and 2008.

Yes, these can be legit.  For example, EI- means the aircraft is registered in Ireland.  Others look corrupt, though.  HZ-AAA is Saudi Arabia, but your HZ example looks too short.  The examples starting with four numbers don't match any country's pattern.
https://en.wikipedia.org/wiki/List_of_aircraft_registration_prefixes
The examples here that start with a string of digits all resolve to actual aircraft, if you prepend an N to them.  (Commenter Ralph J suggested this.)
Corrupt data wouldn't be too surprising.  For 2005, for example, 15000 of the 594000 entries had no tail number at all.


Customs at refueling stops? This question has me wondering: do passengers/crew have to to through customs at refueling stops?

Does it matter if they stay in/with the aircraft vs. going into the FBO, e.g. to use restrooms?

If it is different for different types of flights (e.g. airline vs private), please answer for each.

It depends on the country and may depend on the airport - you have to check the AIP. The term "technical stop" or "tech stop" is often used instead of "refuelling stop", since I guess there could be other reasons than refuelling why you'd need to land and takeoff without exchanging passengers or cargo.

As an example from personal experience flying my 2-seat experimental across the pond, Kangerlussuaq and Narsarsuaq in Greenland do not require crew to go through any customs or immigration checks for a technical stop, while Reykjavik in Iceland does. They let me get out of my drysuit and take a pee break first though, unlike the US CBP!


Do F-4 Phantom II pilots actually fold the wings? In flight simulator X-Plane 8.15, the F-4 Phantom 2 can fold the tip of its wings (well, variable sweep). Is that useful? Why would a pilot fold the wing? To reduce lift for short landing?

As several of the comments have mentioned, the F-4 have the option of folding the outermost section of their wings, as shown in the picture below.

The main purpose of this was simply to save precious space on aircraft carriers, it had no use when flying. There have been some incidents where wings have either started to fold during flight or where the pilot forgot to unfold before takeoff, but it was not designed for this. Many other naval aircraft have the option of folding their wings in a similar manner, such as the F/A-18.

The F-14 Tomcat uses a completely different mechanism to adjust the wing sweep while flying, and although it had a special "parking setting" for the sweep, it was used to adjust the wing sweep according to the speed of the aircraft.

The A-7 Corsair II and the F-8 Crusader also had wing folding, but in addition they could also adjust the attitude of the wing while flying, primarily to improve visibility for the pilot when landing as seen below.


What are the unusually-enlarged wing sections on this P-38 Lightning? Halfway through this video of the Lockheed P-38 Lightning, there's an unusual-looking example.  Notice the enlarged wing sections outboard of the engine bodies, and also how the cockpit fairing extends further aft than usual.

No other P-38 in that video has those features.

What were these devices (and their purpose)?

Also, what is all that gadgetry at the trailing edge of the port wing at its root (with respect to the port engine body), and also that L-shaped thing trailing behind?

It was a test bed that was looking into laminar flow on the wings.

  was converted in 1942 as a two-seater, with an elongated central
  nacelle extending aft of the wing trailing edge, intended as a
  research vehicle to find ways of reducing drag, and was the only P-38
  to have have a full dual set of flight controls. Later it was modified
  with enlarged laminar-flow wing sections outboard of the engine booms,
  complete with slots and boundary layer control by means of exhaust
  bleed air.

There is some discussion on it here as well.


What is the purpose of the serrated trailing edge spoilers on the B52? At around 50 seconds on the linked video you can see the serrations on the trailing edge of the B52's spoiler.

What purpose does it have, and what gives it advantage/disadvantage over the standard spoiler? I've only seen serrated trailing edges on wind turbine blades.

The comments above by John K. and Maury Markowitz are on the right track. The serrated trailing edge of the spoilers has an effect on vortex shedding. It is called that because it is a vortex-shaped airflow that is shed from the rear of an airfoil or other surface.

On modern jet engine nacelles the serrated edges at the rear reduce noise. However, on the B-52 the most likely reason for this feature on the spoilers is to reduce the possibility of vortex shedding inducing vibrations that could cause the wing structure to resonate due to the harmonic oscillation of the vortex. This is also known as flutter. My guess is that at some point in the life of the aircraft design it was determined that this was (or could be) an issue, and this was the solution.

If you think about the last time you flew on an airliner where the pilots deployed the spoilers while still in flight, you may remember the vibration generated by them. That is the consequence of vortex shedding, and that is what the serrated edges are designed to minimize on the B-52.


Can you bust a TFR while operating under IFR? Is it possible for the pilot to be held responsible for violating a Temporary Flight Restriction if the controller makes a mistake while you are operating under an Instrument flight plan (ie: does not deviate you around it, or allows you to go through it without clearing you with the responsible body)?

It is a commonly held belief that the pilot is immune from TFRs while under IFR, but I found a forum thread that seems to indicate the opposite, where both the pilot and the controller were at fault and both received a suspension.  http://www.studentpilot.com/interact/forum/archive/index.php/t-17212.html

(Bonus: Can anyone find a more official reference for that story, and whether there was any legal followup from AOPA Legal or otherwise?)

This is a letter from AOPA that was published in Aero News Network, based on a query made to the FAA on this very topic.

My interpretation of this is that there is no definitive answer, and that both the pilot and the controller have a responsibility, which may answer the question regarding why both parties were suspended in case described in the OP's post.

  Hello Mr. Ward,

  Your email was forwarded to us here in the Air Traffic department of
  AOPA. I contacted FAA headquarters for an official response to your
  question and received the following explanation:  Guess you could say
  it is the responsibility of both the pilot and air traffic controller:

  FAA Order 7110.65 states that ATC shall vector aircraft for separation
  and safety. This includes vectoring aircraft around TFRs as well as
  traffic. For the pilot, the applicable regulation is 14 CFR 91.103
  which pertains to preflight action and states that "Each pilot in
  command shall, before beginning a flight, become familiar with all
  available information concerning that flight," which includes TFRs.
  Additional regulations are covered in 14 CFR 91.13 and whichever CFR
  promulgated the TFR (e.g. 14 CFR 91.137; 14 CFR 91.138; 14 CFR 91.139;
  14 CFR 91.141; 14 CFR 91.143; 14 CFR 91.145)

  From a legal standpoint TFR avoidance is a joint responsibility. (This
  is in no way to be construed as a legal interpretation from FAA's
  legal staff). A pilot should not file an IFR flight through a TFR. If
  they did and that flight violated the TFR, they are subject to
  enforcement action.

  From an Air Traffic Quality Assurance standpoint, a controller should
  not allow an IFR or VFR flight that they are working to fly though a
  TFR. If they did, they would be subject to an Operational Deviation.
  However, looking at the totality of the circumstances: It is the
  pilot-in-command's (PIC's) duty to know exactly where the airspace is,
  just as it is ATC's responsibility to know where the airspace is. If
  ATC gave the pilot a vector that was going to take the aircraft right
  into the TFR and the pilot did not question the controller (just as if
  s/he would if being vectored into an area of known thunderstorms) then
  it is still the final responsibility of the pilot to question the
  clearance, just as it would be ATC's responsibility to question a
  pilot who wanted to fly directly through a TFR. Luckily, we are not
  aware of any instance where a controller let an IFR aircraft fly into
  a TFR. However, we are aware of many cases where pilots filed flights
  directly through TFRs and thought that ATC would vector them around,
  but instead, the pilot departed VFR expecting to pick up an IFR
  clearance in the air. While waiting for ATC to respond and issue a
  clearance the pilot flew through the TFR. In those cases, FAA
  suspended pilot certificates from 30 to 150 days.

  There is no question that it is bad operating practice to file an IFR
  flight through a TFR. During flight planning, pilots should avoid
  TFRs. Arguably, to deliberately file a flight plan through a known
  TFR, in and of itself, would be a violation of 14 CFR 91.103.

  Hope this helps!

  Heidi J. Williams

  Manager

  [emphasis mine]


How were fighter jets built in the 1950's? As far as I know, jets did not see mass production across the world until the 1950's. So I'm interested in how they were built in that time. How many different types of factories were needed? How did those factories work? What supplies were needed and how much manpower did they need per jet?

Right now I'm only imagining two kinds, an airframe factory and an engine factory. I'm very interested in learning more and would not be surprised if there are many other types of factories that go into making a fighter jet.

For simplicity, let's exclude electronics factories like the radar, and weapons factories like guns, bullets, and missiles.

Building an airframe did not change all that much in the jet age. Assuming you are talking about all aluminum aircraft the power plant is somewhat abstracted from the equation in terms of a production line.

Here is the assembly line that Lockheed had for the early P-80 Jets (not all that different than their propellor counter parts). This picture would make it seem as though the airframe was all built in one place as you can see it in various stages in this image alone.

(source)

This is a pretty interesting article about the history of the plane and the role Kelly Johnson played in it.

Like anything in the world of production the assembly line does not change nearly as much as the tooling does. One of main costs in bringing anything to production is cutting and preparing the tooling. Assembling a jet airframe was not all to different than assembling a high performance prop plane of the era.

Things got more complex as they moved to more complicated materials (this came a bit later than your question references but none the less). By all accounts an enormous portion of the SR-71 Blackbird budget was spent developing tooling that could work with titanium.

The engine companies (Like GE/P&W etc) saw much bigger changes as they were now making and testing a completely different product. The P-80 above housed a GE/Allison J33. This would have fallen on to GE to build and like many engines prior would have simply been bought by Lockheed for the plane.

I will try and find some hard production numbers/times for this era of planes.