Could "Mimiron's Head" or "flying machine" fly in the real world? Mimiron's head is an endgame raid reward from the game World of Warcraft that's basically a cup with an upwards rotor mounted on the rear and 2 side rotors pointed downwards.

             is a video which shows what it looks like.

             shows it flying around with a pilot.

The Flying Machine, and the upgraded version Turbo-Charged Flying Machine, is a mount that a player can create themselves using the Engineering profession. It looks more like a traditional helicopter, but instead of a rear-mounted rotor, it has an engine with a propeller on each side.

             shows the Turbo-charged Flying Machine flying around.

now, to me as an aviation-illiterate person, it looks like as-is, either mount could not quite work in the real world, but if you made some modifications, they could work. Is this true? Could you make these helicopter-like vehicles work in the real world? Assume current technology or immediate-future technology (available in the next 5 years).

Could they fly... ...Maybe

The second device looks quite a bit like an Auto Gyro which is very much capable of flight.

The first device looks like (as has been mentioned) the center of gravity would be an issue. If those side pods generated enough thrust along with the main rotor you could get it off the ground however I would think it would be very hard to control.


Is it possible to have dual contra-rotating rotors on a gyrocopter or gyroplane? Are there disadvantages that would outweigh the extra lift? Is it possible to have dual contra-rotating fixed-pitch rotors on a gyrocopter or gyroplane?

It would seem to me that it would provide a lot more lift.  I am wondering if any disadvantages would outweigh the extra lift?

You can get additional lift with a larger rotor, without going to the extra complication of having two of them. Present-day autogyros are very light machines that have more than enough with one rotor. Besides, in the case of the coaxial configuration, the centre of mass of the machine will be much higher, a very undesirable thing for landings, as any gyro pilot would attest...


Why is Tromsø Airport's runway 01 referred to as 36 in the sign before the runway? Runway designations can change due to the changing direction of the magnetic north. Using Google Earth, we can verify that Tromsø Airport's runway 01 has not changed its designation since at least 2005. Nevertheless, as we can see at the start of this video the sign just before the runway refers to the runway as runway 36. Does the 36 on the sign refer to the true direction while the number painted on the runway is the compass direction?

The runway number is changed to 18/36 due to the change of magnetic variation. The image on Google Earth must be outdated. This is from my current (AIRAC 2004) Jeppesen airport chart of ENTC (Tromso, Norway):

The video you linked was uploaded in March 2020, were the runway number had already been changed. I do not know how old the Google Earth image is. According to this thread on a simulation forum, the runway number was changed with AIRAC 1910, which came into effect on 12 Sep 2019.

By the way, both the numbers on the runway and the sign refer the magnetic heading. For more details, see How are runways numbered?.


Is a pilot responsible for CTAF announcements in this scenario? A Cessna 525 Citation Jet is coming in to land and a single-engine Cessna 150 is taking off at a small airport with no ATC. The Cessna 150 stays in continued radio contact and the Cessna 525 Citation Jet does not.

An accident occurs where the Cessna 150 clips the Cessna 525 Citation Jet on the tail end. The Cessna 150 crashes and burns. The people in the Cessna 150 pass away and no one is injured on Cessna 525 Citation Jet.

Is this labeled as an accident although the Cessna 525 Citation Jet did not stay in radio contact after landing when the Cessna 150 attempted to take off?

https://www.cbsnews.com/news/marion-indiana-airport-planes-collide-2018-04-02/

In the U.S., the definition of an accident is covered under 49 CFR Part 830.2:  (emphasis is mine)

§ 830.2 Definitions.
As used in this part the following words or phrases are defined as follows:
Aircraft accident means an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, and in which any person suffers death or serious injury, or in which the aircraft receives substantial damage. For purposes of this part, the definition of “aircraft accident” includes “unmanned aircraft accident,” as defined herein.

From your question, this appears to clearly be an "Accident."


Where can I find drawings or diagrams of the Boeing 737-800's internal layout? I am working on an alternative fuel system for my final school research. I am applying it to the 737-800. Now I could not find info on how the internals are situated. Of course pictures of the cabin are widely available. However I am looking for drawings, pictures or graphs on the cargo compartment, systems placement like gear, hydraulics, pumps or whatever. Basically the whole internal volume and what it is occupied by.

This is maybe a bit demanding but any info is really helpful.

Check out the "Airplane characteristics for airport planning" document for the 737, espcially from page 47: http://www.boeing.com/assets/pdf/commercial/airports/acaps/737.pdf

These kind of documents are created by the airplane manufacturer and are often publically available.


How is the control of airspace over disputed territories determined? Reading this question about the division of airspace over the Persian Gulf reminded me of another potential issue regarding Persian Gulf airspace: the numerous territorial disputes in the area, such as the dispute between Iran and the United Arab Emirates over several islands (Abu Musa, the Greater and Lesser Tunbs, Sir Abu Nu'ayr, and Zirku) scattered over a large area of the lower end of the Gulf, and the unresolved issue of how far northwest the United Arab Emirates extend.

How is the ownership and control of the airspace over these and other disputed areas around the world (of which there are rather a lot) determined?

International air traffic control is divided into Flight Information Regions (FIR) by ICAO through international agreement. Normally this works fairly well. Even countries that are antagonistic to each other wish to maintain safe air traffic.

Currently there is one situation that causes some real consternation, though. That's the dispute between Greece and Turkey over northern Cyprus. ICAO officially assigns the region to Greek ATC, but the northern part of Cyprus, which aligns with Turkey feels that the airspace is theirs and operates a separate ATC that  is not in cooperation with the official ATC, causing confusion for pilots.

They often create long and ridiculous notams to state their point.


What happens if an aircraft's hydraulic system starts leaking during a flight? What will happen if hydraulic fluid starts leaking during a flight? What will happen to the overall performance of the flight, and how will the pilot compensate for the loss of the system?

That depends on the aeroplane. On the B737 for instance, there are three independent hydraulic systems: System A, System B, and Standby System. Normally Systems A and B are operating and Standy is off, only switched ON when necessary from a malfunction.

The flight systems are powered redundantly, with more than one hydraulic system powering the essential aircraft systems. The following systems are powered by the hydraulics:

The hydraulic systems are each redundantly powered as well. For instance hydraulic system A is powered by an engine driven pump and an electrical AC pump. System A is protected from leaks in the engine driven pump lines by a stand-pipe: should a leak occur there, fluid leaks away until the fluid level reaches the stand-pipe, at which point the fluid level is approx. 20% and the engine driven pump circuitry is empty. System pressure is then maintained by the electric pump. Should a leak develop in the electric pump circuitry, the fluid quantity in system A reser- voir, and therefore system pressure, steadily drop to zero.

System B has similar anti-leak features, with a stand-pipe that allows for the Power Transfer Unit (PTU) to operate on the remaining fluid. The PTU is a dual hydraulic pump/motor: one end is driven by System A, the other end can pressurise the fluid in System B.


Is the phrase "going missed" standard in the US? The use of the phrase "going around" is specified by ICAO Doc 4444 as the phrase to use when we're aborting the landing and heading for

another lap in the traffic pattern if we're on a visual or VFR approach, or
the appropriate missed approach procedure if we're on an instrument approach

However, in the US, I often hear the pilot saying "going missed" when breaking off an instrument approach. Is this standard phraseology in the US, or another one of those non-standard phrases which have gained footing? The 7110.65 only mentions the instruction "go around" (which incidentally is analogous, traffic pattern if visual, missed approach if on instruments), but doesn't say anything about the appropriate pilot phraseology. I couldn't find any reference in the AIM (chapter 4 section 2) either.

(I also often hear just "missed approach", which I suppose would be appropriate when checking back in with approach, but not with the tower, although feel free to clarify that for me as well)

According to the Pilot/Controller Glossary (the closest thing to "regulatory" documentation regarding phrases pilots are supposed to use on the radio) there is no GOING MISSED - there is GO AROUND as an ATC instruction (and by analog GOING AROUND as a pilot's response or notification to ATC to inform them the pilot is doing so), which covers both VFR and IFR operations:

  GO AROUND −
  Instructions for a pilot to abandon his/her approach to landing. Additional instructions may follow. Unless otherwise advised by ATC, a VFR aircraft or an aircraft conducting visual approach should overfly the runway while climbing to traffic pattern altitude and enter the traffic pattern via the crosswind leg. A pilot on an IFR flight plan making an instrument approach should execute the published missed approach procedure or proceed as instructed by ATC; e.g., “Go around” (additional instructions if required).

(There is also an IFR-specific EXECUTE MISSED APPROACH in there.)

GOING MISSED is not proper/correct phraseology (though much like "tally one" or "got 'em" in place of "traffic in sight" it will generally be understood by ATC - probably with about the same grinding of teeth as the other two phrases get).

Informing ATC (tower or approach) that you are executing a missed approach by simply saying N12345, Missed Approach is correct phraseology however:

  MISSED APPROACH−
  a. …
  b. A term used by the pilot to inform ATC that he/she is executing the missed approach.
  c. …

and is probably what should be used in place of "Going Missed".


Can a glider make a go-around? Since gliders don't have engines, is it possible for them to go around? Are there any extra features on a glider to try to prevent that situation from happening?

No. A (pure) glider cannot make a go-around in the way a powered machine can. The glide path can be influenced by airbrakes, flaps,  chutes or slipping, but mostly those are for reducing your L/D, i.e., steepening the approach (you win again, gravity!).
Gaining height without updraft is only possible by converting kinetic energy (speed), and that gain is limited by the stall speed. So while you can rise a few meters when you pull up from landing airspeed, you will find yourself way too high above the runway at minimum speed and hoping for the best.
The highly enjoyable* spectacle of a low fly-by of a glider is achieved by starting with really high (unlandable) speed which is then converted into height and shortly followed by the inevitable landing**. For some older (mostly wooden) gliders, even this is not a very good idea because they combine a lower VNE with lower L/D ratios,  leaving you low and slow after pulling up from redline speeds.
In a glider, you get one chance for a smooth landing (freak thermals excluding). But a properly trained pilot gets used to this very quickly. A proper landing procedure together with brakes, flaps, etc. will bring you down safely.
*but not necessarily safe or recommended
** unless you catch a proper thermal or dynamic updraft.


What do different runway depictions mean in the Chart Supplement? I cannot find a digital Chart Supplement (AF/D) glossary.

What is the length requirement to depict a runway as a dashed line vs. solid black?

The depiction for Melbourne, Florida shows one runway with a dashed line and another as solid.

At JFK, all the runways have dashed lines. What do the different depictions mean?

The glossary I'm looking at (page 13 from the current South Central US Chart Supplement) says that that style of dashed line indicates Runway Centerline Lighting.  So runways that have the dashed lines have lights on the runway.

The complete chart supplements are available online from the FAA, and the glossary for each one is easily found about Page 13 for each section.


What is the maximum number of cabin crew members on an A320 load sheet? What is the maximum allowable number of cabin crew members to be mentioned on the load sheet for A320, with respect to weight and balance? And does the number of deadheading crew members add to this figure ?

I believe that there are six crew seats in the A320 cabin. as long as the operating crew occupies these seats they will be included the crew figures for loadsheet purposes. In the event that these seats are occupied by non-crew they will need to be included manually. Not really common nowadays but it was routinely done in the 90s.

In the event that there is crew occupying a passenger seat (deadheading) they will be trimmed as a passenger.

The reason is most loadsheet programmes will adjust the Dry Operating Index  (and dry operating weight) depending on the number of crews entered in the crew field (eg 3/5). If a crew (deadheading or otherwise) is occupying a passenger seat, the system will only be able to account for this person if he is checked in.

Depending on the airline and the local country regulations it may not be possible for deadheading crews to travel on the General Declaration, instead they may be required to have tickets and be included in the passenger manifest.

To summarise, everything on the airplane must be accounted for, both in terms f weight as well as its effect on the trim, irrespective of whether it is a person on a jumpseat or passenger seat.

Hope this helps.


Are four-engined airplanes subject to ETOPS equivalent rules? I've heard of ETOPS, which permits the maximum duration for which a two-engined airplane can fly on one engine to the nearest airport.

Are 4-engined planes such as the Boeing 747 and Airbus A380 subject to any equivalent rules? If not, can these planes safely fly on just one engine for as long as needed?

Also, how are aircraft given different ETOPS certifications? What makes the 787 get ETOPS-330 and the 767 only ETOPS-180 despite the similarity in range and (to an extent) engine power and design?

Yes, three- and four-engine airliners follow 'Long-Range Operations' restrictions just like twin-engine airliners.
From WikiPedia:

Airbus proposed to replace ETOPS by a newer system, referred to as LROPS or Long Range Operational Performance Standards, which would affect all civil airliners, not just those with a twin-engine configuration
(...)
The FAA has decided to use the single term, 'extended operations,' or ETOPS, for all affected operations regardless of the number of engines on the airplane.

The large 4-engined airliners can not reliably fly long distances on one engine only.  But  they can fly on three engines just fine.  When only two engines are available they divert to the nearest airport.
The ETOPS rules become relevant whenever a three- or four-engined jet diverts more than 180 minutes from the nearest airport.
For more information, refer to the airliners.net thread on 3 And 4 Engine Planes Requiring Etops.


What parameters to focus on when constructing a wing for turning? I want to construct a flying wing (glider) with the sole purpose of performing a helical turn (or a circular turn with no propulsion attached) with somewhat of a fixed radius. What should be the main parameters of the flying wing that I should focus on?

Thanks

Strength, ability to withstand the G forces of turning.  Secondly, having a stall Angle of Attack as high as possible.

A low aspect ratio wing with a very thick airfoil is a good candidate, such as the ones designed by Hugo Junkers and seen on Fokker planes of 100 years ago.  These work very well for slow, turning flight.

Another candidate would be the delta.  Strong and easy to construct, deltas offer a very high stalling AOA, making them very good at turning tightly.

Deltas have more drag for a given amount lift than a straight wing, so the first candidate will stay in the air for a greater amount of time, the second may give a thinner helix.

Good reading articles can be found in Air and Space magazine:  "What the Red Baron never knew" and "The Perfect Airplane Wing".


What type of aircraft would fly with an orange light at night? I know planes usually fly with red lights which seem small in the sky, but last night i saw a bright orange blinking light traveling through the sky; it was bigger then a star but was orange. I thought it might be a helicopter, although I read it could have been a comet or a meteor.

While normally red in colour, anti collision lights can often appear more or less orange, depending on the background and atmospheric conditions. It is impossible to determine the aircraft type just based on the fact that it has a orange light on it, since almost all aircraft have reddish orange anti collision lights.


Engines more powerful than the brakes? This might be more of an anecdotal question, but are there any aircraft where under full throttle (with afterburner in worst-case) where the wheels wouldn't provide enough friction against the runway to keep the aircraft from starting to roll (and skidding the locked-up tires)?  Obviously if the runway was iced it would make a difference in friction; I'm more wondering about in normal runway temperatures where it's just rubber on concrete.

Many small 4 to 6 seats propeller airplanes can overcome their brake/wheel holding capability, on concrete and ashpalt.  My Cessna Cardinal is 180HP, I do engine pre-takeoff runup checks at 1700-1800 RPM. Going to 2600, the plane will start moving.  Many other planes of similar size are 300 HP, and they definitely won't hold. We only have two 5" or 6" disc brakes, no power assist, pushing the pedal tops with our toes. Or a hand-pull parking brake.


What is the power source of the clock in glass cockpits? I always get the impression that, once the shutdown & secure checklist is completed, there would be absolutely no electricity to any components in the cockpit or any aircraft systems.

However, most flight management computers know the current time. The time is also needed for GPS positioning.

How does the aircraft keep the time when the power is off? Is there a very small battery (similar to computer motherboards) which needs to be replaced once every few years, or is there a tiny electric current drawn from the batteries at all times?

There are two ways this generally works:

A low-current hot buss that is always connected to the system battery
A small rechargeable battery that powers low-power time and memory circuits

The first is common in aircraft with hard-wired systems, while the second is the case for nearly every handheld-style GPS.

While GPS does not necessarily need to be powered all the time, it dramatically speeds up the satellite position lock if it is

close to the correct time and
can produce the GPS 'almanac' (coarse orbit) from memory
can produce valid ephemeris (detailed orbit) data from memory
has a valid last known position

The time, position, and almanac information give the GPS hints on which satellites to search for first. Once the first satellite is locked on to it can acquire a time signal and the time is quite accurately synchronized to the GPS system. The almanac is successively used to search for more satellites that should be in view, but will fail over to look for others if these are not found. Once a satellite is found, if the ephemeris data has expired, it will listen for the ephemeris information which takes around 30 seconds to receive. This is the main difference in the 'hot' 'warm' and 'cold' start time for a GPS receiver.

If no power is maintained in the GPS, at the very least the time will be lost, and more typically all of the almanac information is wiped out as well, resulting in a position acquisition time of a minute or more.


What are the regulatory categories of aircraft defined by the FAA? What are the different aircraft regulatory categories aircraft defined by the FAA? Are there any exceptions?

The FAA defines several different types of aircraft, which have different applicable regulations. For fixed-wing aircraft, airworthiness for normal, utility, acrobatic, and commuter categories is covered in Part 23.
Note: Seat number excludes pilot seats. Weights are maximum certificated takeoff weights.

Normal category

Seats: 9 or less
Weight: 12,500 lb or less
Allowed maneuvers:

Any maneuver incident to normal flying;
Stalls (except whip stalls); and
Lazy eights, chandelles, and steep turns, angle of bank 60 degrees or less

Utility category

Seats: 9 or less
Weight: 12,500 lb or less
Allowed maneuvers:

Normal category, plus:
Spins (if approved for the particular type of airplane); and
Lazy eights, chandelles, and steep turns, or similar maneuvers, angle of bank can be more than 60 degrees but not more than 90 degrees

Acrobatic category

Seats: 9 or less
Weight: 12,500 lb or less
Allowed maneuvers:

Anything not prohibited due to flight tests

Commuter category

Seats: 19 or less
Weight: 19,000 lb or less
Engines: 2 or more
Allowed maneuvers:

Any maneuver incident to normal flying;
Stalls (except whip stalls); and
Steep turns, angle of bank 60 degrees or less

  Except for commuter category, airplanes may be type certificated in more than one category if the requirements of each requested category are met.

Beyond commuter category, there is the transport category. Multi-engine airplanes satisfying either of the below requirements must be certified in this category. Airworthiness for the transport category is covered in Part 25.

Transport category

Seats: 20 or more
Weight: more than 19,000 lb

For rotorcraft, there are two main categories: normal and transport. Airworthiness for the normal category is covered in Part 27.

Normal category

Seats: 9 or less
Weight: 7,000 lb or less

Multi-engine rotorcraft satisfying these conditions may be certified under transport Category A (see below) if they satisfy certain conditions.

Airworthiness for the transport category is covered in Part 29. There are sub-categories here as well.

Transport category

Category A

Seats: 10 or more
Weight: more than 20,000 lb

Category B

Seats: 9 or less
Weight: 20,000 lb or less

If a rotorcraft only satisfies one of the requirements for Category A, it may be certificated under Category B with certain additional requirements.

  A multiengine rotorcraft may be type certificated as both Category A and Category B with appropriate and different operating limitations for each category.

There is also a manned free balloon category covered in Part 31.

  A balloon is a lighter-than-air aircraft that is not engine driven, and that sustains flight through the use of either gas buoyancy or an airborne heater.

Part 21 addresses the certification process itself, and includes special types of certificates for other aircraft.

Primary category

Power sources allowed:

None
Single naturally aspirated engine (stall speed 61 kt or less)
Rotorcraft with 6 lb per square foot main rotor discs loading limitation (sea level standard day)

Weight: 2,700 lb or less (seaplanes 3,375 or less)
Seats: 3 or less
Unpressurized

The restricted category allows a plane to not meet certain requirements under the normal regulations. The aircraft must meet one of the following conditions:

Restricted category

Requirements of any regular category, except any that are "inappropriate" for the aircraft's purpose
Armed Forces aircraft modified for a special purpose

US Armed Forces surplus aircraft can also be certified under one of the below conditions. The FAA has some leeway to waive requirements or add additional ones.

Surplus aircraft of the Armed Forces

Designed and constructed in the US, satisfies certain regulations
Counterpart of previously certified civil aircraft, complies with those regulations

Special certificates are issued for cases where the aircraft is not certified under the regular categories. These allow operation of certain aircraft for certain purposes.

The experimental certificate is for special cases.

Experimental certificates

Research and development
Showing compliance with regulations
Crew training
Exhibition
Air racing
Market surveys
Operating amateur-built aircraft
Operating primary kit-built aircraft
Operating light-sport aircraft

The light sport certificate is for light aircraft that may be operated under special conditions. There are 5 categories of LSA.

Light sport certificates

Airplanes
Gliders
Powered parachutes
Weight-shift-control aircraft (commonly called trikes)
Lighter-than-air aircraft (balloons and airships)


Why do all fifth generation fighters (J20, F22, SU57) put their wing above the fuselage? I heard that upper wing could increase stability, but why do fighters need it? Or are there some other reasons? Please specify.

One big reason is to make room for external stores such as fuel, weapons and electronics packs. A low-wing design must have longer and therefore heavier and bulkier undercarriage if ground access to the underwing hard points is to be adequate.

Also, the upper surface of a high wing is larger and cleaner, providing better lift over the fuselage and reducing the overall size of the wing.

Another trick which it allows is to create a waverider effect between the engines, providing supersonic lift with less drag.

The extra stability of the high wing position is unwelcome in a fighter and is typically countered by giving the wings a little anhedral, a slight downwards slope from root to tip.


Is airspace above KKIC class G at 3,500’ MSL? Flying from KPRB to KKIC, in a straight route shown on SkyVector, except keeping slightly to the East of R-2504A&B, holding an altitude of 3500MSL, except for normal takeoff and descent rates, am I correct in the following?

Taking off from KPRB, you're in Class E airspace within the dashed magenta lines.
Once you're out of KPRB's dashed magenta lines, all the way to landing at KKIC, you're in Class G airspace.

I'm watching a video from PilotEdge, and at 47:33 he roughly says "We know we're going to be in Echo as we take off.  We're going to be in Echo for the rest.  We know we're in Echo by default, because there's nothing else around."

I think the "We're going to be in Echo for the rest" part is wrong.  Am I correct here?  If I'm wrong, can you please explain why it's Class E?  It's not within a fuzzy blue or magenta line, and we're flying at 3500MSL, so obviously never going above the Class G 14500AGL ceiling.

I think he's just simplifying things because in another video said VFR pilots in the air can practically treat all Class G airspace as Class E, not using the less restrictive weather minimums, and be safer.  But, starting to learn aeronautical charts and flight planning, I want to know if I'm fundamentally starting with a misunderstanding or not.  The YouTube video has no comments about this statement.

As long as the flight climbs above 1,200’ AGL before exiting the area where class E begins at the surface, the whole flight is conducted in class E airspace until descending below 1,200’ AGL on the approach to the KKIC airport.

The point of confusion I think is where you've read that class G airspace goes up to 14,500 MSL.

  Class G Airspace within the United States extends up to 14,500’ MSL.

But first you must consider the following.

  Class E Airspace exists at 1,200’ AGL unless designated otherwise.

We can see to the west that there are areas where there are exceptions to the 1,200’ AGL specification, but this flight plan does not go through them. This means that the en route phase of the flight, if conducted above 1,200’ AGL is conducted in class E airspace.

We can reference all this using the Aeronautical Chart User's Guide.


When must airliners follow airways? Please give a basic explanation of how commercial aviation traffic is routed for readers without any foreknowledge:

Can commercial aircraft only follow airways like cars on highways ?
Or are airlines free to choose a straight line between airports (excluding probhibited and restricted airspace) ?
Or is it a mix of both ? If so:

When must airliners follow airways ?
And when are they permitted to leave them (absent emergency) ?

What differences (if any) are there between traffic over sea and over land ?

Commercial airliners generally fly IFR as such they do what ATC tells them to do. They are not free to chose their own path. The airway system in the USA and elsewhere on the globe stems from the pre-GPS era when VOR's and other ground based nav aids were the predominant method of navigation. Airways tend to be either between VOR's or between points you can triangulate with a VOR. The system was built around this idea of traffic routing and in the GPS days it has simply stuck. As the FAA shuts down VOR's slowly some of the airways remain and seem a bit arbitrary but GPS allows us to follow them easily.

The FAA has a brief on it here.

Broadly speaking aircraft can request a deviation for weather or other inflight issues like turbulence but aside from that courses are followed as they are assigned.

The FAA has discussed routing directly but until the nextGen system is in place its likely not going to be a widespread reality.

  What differences (if any) are there between traffic over sea and over land?

At least over the Atlantic there is the North Atlantic track which is a set of predefined routes. Since there is no ATC over the ocean aircraft do a certain amount of self regulating.


Which gas is used to fill the evacuation slides of modern aircraft? We have seen that after an emergency landing when the airplane needs to be evacuated promptly, evacuation slides get deployed immediately. I am not sure if normal air is being inflated in those slides or do they use some other gas in them?

They are filled with carbon dioxide, oxygen and nitrogen. See here for reference.

From the linked article:

  Slides inflate with an initial boost from a canister of compressed
  carbon dioxide and nitrogen. The canister provides only about
  one-third the volume needed to inflate the slides. The remaining
  volume is supplied by ambient air, channeled into the slides through
  aspirators.

  When the inflation mechanism is triggered—by a lanyard pulled by the
  slide as it tumbles from its storage case—gas from the canister
  accelerates through the aspirators at high speed, creating a vacuum
  that sucks ambient air into the aspirators through louvers. When the
  slide is fully inflated, the louvers close.


Do seaplane bases ever have marked "runways" or approach lighting? Some seaplane bases have prescribed areas for landing, but are the landing areas marked by buoys or lights? If so are "runways" outlined in the water or just a general area?

Do they have IFR approach procedures?

Are the landing areas marked by buoys or lights?
In at least one specific instance, Yes.

The seaplanes that operate out of Lake Union, Seattle, have "Advisory Buoys" that help make the many sailboats, kayaks, and motorboats on the lake aware that planes will be arriving or taking off.

The buoys have Pilot Controlled Lighting (PCL) that will turn on yellow flashing lights.  They are typically activated approximately 3 minutes before any departure or arrival.

The buoys do not restrict boat movement; they are advisory only.

I am not aware of any IFR procedures for a seaplane base, but I do not know for sure.


How do you convert true airspeed to indicated airspeed? Is this something found in the POH? I know there is a IAS and CAS chart.

Short Answer

Getting to grips with Aircraft Performance and Calibrated Airspeed are two good places to start!

The short answer:

From TAS to IAS $IAS=f(TAS)$:

$$IAS = a_0 \sqrt{5\left[\left(\frac{\frac{1}{2} \rho {TAS}^2}{P_0} + 1 \right)^{\frac{2}{7}}-1\right]} + K_i $$

From IAS to TAS $TAS=f(IAS)$:

$$TAS = \sqrt{\frac{2 P_0}{\rho}\left[\left(   \frac{ (\frac{IAS - K_i}{a_0})^2 + 1}{5}  \right)^{\frac{7}{2}} + 1 \right]} $$

WARNING: the units should be taken as SI, ($\frac{m}{s},\frac{kg}{m^3},Pa$).

In particular:

$a_0$: speed of soundat sea level in ISA condition = $290. 07 \; \frac{m}{s}$
$P_0$: static pressure at sea level in ISA condition = $1013.25 \; Pa$
$\rho$: density of the air in which you are flying $\frac{kg}{m^3}$
$IAS$: indicated Air Speed $\frac{m}{s}$
$K_i$: is a correction factor typical of your aircraft. You should find it in the POH.

How to get to this formula, see the long answer below.

Long Answer

From the definition of dynamic pressure:

$$ q_c  = \frac{1}{2} \rho v^2 $$

Where $v = TAS$, I am assuming you are interesting in subsonic speeds (cross-country flight), so we don't consider compressibility effects for the CAS:

$$CAS = a_0 \sqrt{5\left[\left(\frac{q_c}{P_0} + 1 \right)^{\frac{2}{7}}-1\right]} $$

Substituting the dynamic pressure definition in the $CAS$ as a function of $TAS$

$$CAS = a_0 \sqrt{5\left[\left(\frac{\frac{1}{2} \rho {TAS}^2}{P_0} + 1 \right)^{\frac{2}{7}}-1\right]} $$

Where $a_0$ is $295.070 \; \frac{m}{s}$ and  $P_0$ is $101325 \; Pa$. the density $\rho $ is the density at your altitude that day, you can get it from International Standard Atmosphere calculator or table/formulas.
If you measure it from your aircraft instruments $\rho = \frac{P}{RT}$, with $R=287.058 J kg ^{-1} K^{-1}$. You should give in Pressure in Pascal (not $hPa$) and most important temperature in Kelvin $K$.
Reverting the formula above (double proof is appreciated):

$$TAS = \sqrt{\frac{2 P_0}{\rho}\left[\left(   \frac{ (\frac{CAS}{a_0})^2 + 1}{5}  \right)^{\frac{7}{2}} + 1 \right]} $$

Being
$$
IAS = CAS  + K_i \\
CAS = IAS - K_i
$$

Where $K_i$ is a correction factor typical of your aircraft. You should find it in the POH.

Finally we get TAS as a function of IAS $TAS=f(IAS)$

So:
$$TAS = \sqrt{\frac{2 P_0}{\rho}\left[\left(   \frac{ (\frac{IAS - K_i}{a_0})^2 + 1}{5}  \right)^{\frac{7}{2}} + 1 \right]} $$


What would prevent a solar powered aircraft staying aloft forever? Focusing on aircraft, not balloons, I found this question that led me to some basic research on atmospheric satellites. I imagine the technology has evolved since NASA's research more than 10 years ago.

Given the following points:

The aircraft cannot stay in flight forever, as it must land for maintenance (as would any aircraft).
In 2001, NASA planned a 40h long trip based on solar powered technology.
A fuel-powered UAV can stay up to 33h in flight.
The Qinetiq Zephyr stayed aloft about 2 weeks.
Redundancy can be added to continue operation in case of equipment failure (as in any commercial aircraft).
'Real' satellite can stay airborne for several years (payloads seem to be able to operate several years without maintenance)
If the aircraft can land, the payload and equipment do not have to be as reliable as they would on 'real' satellites, as they could be changed or repaired.

For an atmospheric satellite based on solar-powered airplane technology such as the NASA's Helios, operated in normal conditions, what is the most restrictive element that make landing compulsory?

The most common failures in planes start with: a human mistake or a mechanical failure. Where, of course, mechanical failures are much more likely to happen on moving parts.

Satellites have very little moving parts: you get couple servo motors to adjust the angle of your equipment such as the solar panels and the antennas. Both happen in units of full rotations a day. You also often have some small rocket engines to correct the satellites course, but they are rocket engines whose moving parts comprise more or less just one valve.

In a plane, however, you have pieces that move very fast and fluids of all kinds (not only fuel which you need not have on a solar-powered plane, but also lubricants, hydraulics etc.), also very sensitive mechanical sensors whose non-stop operation is crucial for the flight. This all needs to be inspected, oil levels checked, hydraulics checked. Last but not least, the weather in the space is quite calm, compared to the atmosphere. Depending on how high you fly, you meet clouds, storms, birds, temperature changes etc., which all can add to the wear of things and make things require maintenance.

I'm not sure which would be the limiting factor, but I think that either some equipment wouldn't be operational without maintenance, or you would get a mechanical failure of some kind.


When (if ever) can ATC order an aircraft to go around? Can ATC order an aircraft to go around if there is a tailwind? Or should ATC give the pilots the current wind information and let them decide whether to go around or land?

In real world practice, ATC will have a specific direction for traffic to land and takeoff based on their specific criteria. Regardless of which direction ATC chooses to make the traffic flow, the PIC can choose any runway and/or direction he wishes to land. As long as both parties coordinate and agree, the aircraft can land based on the ATC’s chosen direction or the pilot’s chosen direction. ATC will usually make sure approaching aircraft are kept aware of the wind conditions so that agreement can be made. Either party can decline/deny the approach and/or landing.

An example of this is when aircraft approach our local Class D airfield VFR. They announce that they are inbound with the intention of landing. The PIC will typically then accept whichever runway ATC assigns. When an aircraft approaches IFR, they will typically know which approach and runway they wish to use. The PIC will typically have already negotiated/coordinated this with approach before being transferred to tower. If the aircraft is approaching the airport practicing IFR in VMC, they will negotiate/coordinate the approach and runway to use directly with the tower.

ATC is responsible for traffic separation in their area of jurisdiction. Although, the PIC has ultimate authority over the safety of flight of his/her aircraft, ATC has the authority on whether that flight can include ATC’s physical domain. That domain includes specifically the runway and taxiway surfaces. They can choose whether or not to give an aircraft clearance to use the runway. They can also revoke that clearance for the sake of safety. Some instances where ATC may revoke clearance and call for a go around include:

Reversal of surface winds.
Windshear.
Runway incursion by another airplane.
Runway incursion by a ground vehicle or personnel.
Runway incursion by an animal.
Ceilings or visibility going below acceptable runway visual range.
Closing the airfield due to an accident or emergency.
Inadequate spacing between aircraft.
Landing gear issues unnoticed by the landing pilot.
other safety issues specific to ground or airfield environment safety.

Even before an aircraft approaches the airport for landing, ATC can prohibit them from entering their airspace in its entirety. The aircraft will have to remain outside of the airspace until ATC gives them the clearance to enter.

All of this can be superseded by the PIC in the case of an actual emergency on the part of the aircraft.


Is it legal to use an online logbook? I am a computer programmer and student pilot. I want to make a computer program I can use to store my logs. Can I legally do this? Can I legally store Logbook endorsements with this? Are there any rules I need to be aware of? For the signatures can I use a pilot's certificate number instead?

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

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

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

An electronic signature may be in the following forms.

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

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

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

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

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

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


On an inverted aircraft, is the ILS glide slope sensing reversed? If I'm halfway through a barrel roll on final descent, on an ILS, will I get reverse sensing on my glide slope indicator?

Well first off said stunt is illegal under 91.303 aerobatic flight regs and 91.13 careless and reckless operation of an aircraft.  And it's also very dangerous.  But no, it would not result in reverse sensing due to the fact that the ILS system is only capable of sensing whether it is receiving more of the 90 Hz signal as opposed to the 150 Hz signal and interprets this as either above or below glideslope.  It cannot differentiate between erect and inverted flight.


Can the new multi scan weather radar on the A320 see low level cumulus? Is it true that in the new multi scan weather radars fitted in the A320, low level cumulus clouds are not picked up?

I'm not sure where you got your info from, but here is what I know of the Multiscan radars from Collins and Honeywell:

Multiscan displays precipitation from the highest tilt to the lowest so if the cloud is dense enough, even if it's a low level cloud, it will still cause returns. Keep in mind - just because the clouds are cumulus doesn't mean it has enough density to cause the WX-Radar to display any returns.

If you're talking about the dark-cockpit-concept, then yes, at certain high altitudes, the clouds will not show on the radar. This is because the OEMs want us pilots to only see what will pose a potential risk of turbulence and safety while at that particular altitude. If you want to see what's directly underneath your aircraft, the radar should be set to manual mode. However, this only happens during cruising at high altitudes.


Are there any certification requirements for steering bypass or lock pins? Are there any requirements for aircraft bypass and/or lock pins? Do they have to be somehow certified by local or international aviation authorities?

The steering bypass pin on modern airliners serves to isolate the nose wheel from the hydraulics so that movement of the nose wheel will not damage the hydraulic system. What the pin does is usually hold a bypass-valve open, allowing fluid in the actuator which is displaced by the movement of the nose wheel to 'bypass'.

This would be the most simple solution and most manufacturers have adopted this. Exceptions would be aircraft which have an electric nose wheel steering in which case the pin is not used, the pin being deactivated by a switch in the cockpit (ATR72).

In some older aircraft like the DC-8, the drag link (scissor-like link usually seen behind the nose-gear) has a quick disconnect. When disconnected the wheels are only fixed by the central oleo and can rotate thru 360 degrees. A bit of a pain for the push-back crew when reconnecting! On modern aircraft this can be done as well for non-normal operations like in the hangar or aircraft recovery. In normal conditions the actuators limit the angle of the nose wheel.


Why do the engineers need to be on board during testing? I just finished watching National Geographic's Megafactories: Boeing 747-8.

During the test flights, a bunch of engineers are on board the plane, presumably controlling the water tanks that distribute weight, and collecting the data.

Another time I'd seen it was when they were testing detection systems for microbursts. There were about a dozen engineers sitting on the plane, watching monitors while the crew deliberately flew into hazardous conditions.

Why do they risk the safety of these engineers, when presumably the work they're doing could be automated or controlled remotely? For data to be observed, couldn't they do that from the ground?

Is this a case of "we've always done it this way?" Even now that we probably have the technology that would allow the engineers to avoid having to go on test flights, I'm guessing that changing this procedure would be a lengthy and difficult process.

Besides the pilots, why does anyone else need to be on board?

More and more data is collected in flight testing of aircraft. While 50 years ago they might have only designed for a small number of scenarios, the advances in computing allow them to design modern aircraft for thousands of scenarios. Modern certification standards include more and more requirements, which include flight testing for many of these requirements.

While some information is sent to the ground (like in this video), other information may not be. Airplanes in flight test have sensors for temperature, pressure, stress, and many other parameters located throughout the plane. These generate a lot of data, more than may be practical to send on a live data link. There may be several reasons that the engineers would want to analyze a lot of information onboard.

Some of the tests need to have multiple parameters coordinated with the pilots. If they are flight testing stall, for instance, they need to be sure they have flight parameters are correct for that test. The engineers give the pilots guidance on getting the airplane into the right configuration. The engineers also verify that the the information they collect is sufficient for the needs of the test. It's much more expensive to come back and realize they didn't get what they needed and must go back up to re-run the test.

Some of the data is also critical for safety. One subject of the tests is flutter. Flutter conditions can be very dangerous to the aircraft. The engineers help monitor the data and make sure that things don't get out of hand. If a data link were to be interrupted in a case like this, safety could be compromised.


Can turboprop blades break the sound barrier? This question doesn't relate to the actual speed of the aircraft, but of the blades themselves. I have heard helicopters had problems of this happening if the rotors spin too fast it can break the sound barrier, so could this happen to a turboprop?

Can it happen: Yes

Does it happen: Generally no

As a matter of the pure physics propeller tips can go supersonic and some times do. There is at least one case of this being done by design on the XF-84H which was built to be one of the fastest propeller planes.

The main issue it faced was the noise generated by its supersonic prop. It is considered one of the loudest aircraft ever made as its prop was supersonic even at idle speeds. Due to the shock waves generated by breaking the sound barrier great care is often taken to ensure that propellers don't go supersonic.


Are municipal airports in the U.S. treated differently than most public places in regards to legal, holstered, loaded firearm carry? Is a municipal airport treated like a normal public place which requires signage or registration with a no-carry list to ban firearms from being carried on the premises, or...

... is a municipal airport treated like a government facility such as a courthouse, post office, or DMV office?

Or is there some other rule regarding guns that are loaded, holstered or otherwise carried on or about a person?

Airport terminals designed primarily for part 121 airline operations which are actively screened by the Transportation Security Administration are beyond the scope of this question.

Laws vary from state-to-state, so if carry is not legal in those states, then this question is not being asked in regards to those states, obviously.

Related: Are US pilots permitted to carry & use their firearm in countries where guns are illegal?

As you hinted, it depends on the state. And the airport.

Some states allow travelers to carry their hunting rifles or pistols aboard general aviation planes. It is recommended that they buy the ammunition at their destination, if they can, for safety reasons.

Best answer I have is this:

  Any private pilot desiring to transport a firearm, weapon, or similar device must review the appropriate regulations and should contact the local airport management or law enforcement authorities for approval to land at any airport if any firearm is on board.

Source: AOPA

Another way to look at it, if you have your own private airstrip, who's to stop you? Just contact the local authorities of your destination before heading out.

For unconcealed firearms in a public airport:

  44 States allow lawful carry of firearms in the common terminal and baggage claim areas of airports.

Source: Florida Carry and CBS News (2008)

Disclaimer: contact local authorities before trying it, aka don't try this at home.


What is the difference between a forward, aft, high and low center of gravity? I would like to know the difference between when the center of gravity (CoG) is forward and aft? And high and low?

I already know that the lower the CoG, the greater the static lateral stability. A forward CoG is generally more stable than an aft CoG. So does this mean that a low CoG is the same as an aft CoG?

Note: If the effects of an AFT CG is not the same as Low CG, then what's the effect of each one of them or what's the difference between them?, and most importantly when is the CG is AFT or Forward?, and when is the CG Low or High?

I'm not sure I'm understanding what you're trying to get at, but let me try to answer the sentence:

  most importantly when is the CG is AFT or Forward?, and when is the CG Low or High?

Whether the CG is aft or forward refers to its position along the longitudinal axis of the airplane, that axis that runs from the aircraft nose to the tail. Usually if people refer to just "the CG" they're typically referring to the longitudinal position of the CG as that is generally the most critical. Boeing refers to the longitudinal axis measurement as the BA, balance arm, although the longitudinal CG is usually spoken of in terms of the percent of the mean aerodynamic chord.

Let's say you have a freighter with a single 10,000 lb pallet in it. If that pallet is in the forward most position capable of handling it, the longitudinal CG would be considerably more forward than if the pallet were in the aft most position. Very possibly in either instance the respective forward and aft CG limits would be exceeded. If a loadmaster said only, "I've got a forward CG," he might mean that the load is forward of the forward limit, or he might simply mean that the load is within the limit but more forward than he likes.

Now let's say that we split the 10,000 lb pallet into two 5,000 lb pallets, and we put one of them in that most forward position on the main deck and the other in the same longitudinal position on the lower deck. That wouldn't change the longitudinal CG because both pallets are at the same longitudinal position. However, it would change the vertical CG as measured along the vertical axis. Loadmasters on 747s don't have to worry about the vertical CG because there are no defined limits for it in 747 weight and balance manuals. Loadmasters on 767s, however, do as there are defined limits. If a 767 loadmaster says he has a high CG, he can mean that the maindeck load is too great given how much is in the lower deck. He also might mean that the vertical CG of the maindeck load itself is greater than 42" above the maindeck floor. Boeing refers to the vertical axis measurement as the WL, water line.

Though you didn't ask about it, there is a third axis, the lateral axis, extending from wing tip to wing tip so to speak. Boeing refers to the position along this axis as the BBL, body buttock line, and there are typically limits as to how far from the aircraft centerline the lateral CG can be.


Why has aluminium, rather than steel, prevailed in airliner construction? As any cyclist knows, steel has many advantages over aluminium:

it's stronger (for the same size)
it can handle greater forces without needing to be stiffer
it has better fatigue characteristics
it's easier to work with
and most importantly of all, it offers a more responsive and comfortable ride.

On the other hand aluminium is much lighter (for the same strength), which obviously is pretty important in an aircraft.

Even so, steel-framed bicycles aren't always heavier, or significantly heavier, than aluminium-framed bikes of similar strength, and in engineering the strength of a construction is not only determined by its materials, but also its design.

When did aluminium become the default material for the vast majority of an airliner's construction, and is its strength-for-weight advantage the principal reason?

You are right, on first sight it is actually surprising that aluminium prevailed. It comes with some disadvantages:

Crack growth must come first in this list. With only a small cyclic load, cracks in aluminium will relentlessly grow. This requires frequent checks and has caused many accidents. Fortunately for aluminium, this fact was only discovered after WW II when the lifetime of aluminium airframes shot up from dozens to thousands of hours, so aluminium was already firmly established as the premier structural material.
To connect two aluminium parts, only riveting or bolting are available. Recently, bonding has become viable, too. Steel offers a third choice in welding, which gives it the advantage in vehicle construction. Again, history gave aluminium a head start, because when the first metal airframes were designed, welding was still relatively little developed, so the restriction to riveting was not felt as the disadvantage it is.
Corrosion: Here it is generally better than steel, but far worse than stainless steel which would be the prime candidate (next to maraging steels) for airframes were aluminium not available. During the Berlin Airlift, salt or baking powder could only be transported by seaplanes because it would had permanently damaged the landplanes. Seaplanes used special, corrosion resistant alloys which were needed in the marine environment.

In the end, however, this is still outweighed by the principal advantage of aluminium: Its low density. This allows to use thicker gages for the same weight, so the buckling strength of aluminium skins is far better than that of equally heavy steel skins. In aviation, the demands of aerodynamics make the use of crimps or reinforcing seams impossible, and only the labor-intensive addition of closely spaced stiffeners could remedy this. Such a stiffened steel skin would still be inferior when it comes to hail damage or handling loads, though, so aluminium was the obvious first choice.

In order to keep material cost down, Junkers built his first metal aircraft from steel but had to switch to corrugated aluminium in order to make them light enough. Note that the structural integrity of his designs was ensured by a steel truss, and only the covering was from corrugated aluminium. Later stressed-skin designs did away with the steel truss.

To compare the strength and stiffness of different materials independent of their density, you can use their breaking length and specific modulus, which can be expressed as their strain length. Surprisingly, most structural metals have a comparable value and only composites can set themselves apart.

Despite its nasty failure characteristics, aluminium has defended its position as the dominant structural material: By the time composites were developed, the engineers and certification authorities had learned how to handle aluminium and had created a barrier to entry in the form of a host of tests and approved construction techniques which severely harmed composites. If all the materials we know today had been available a century ago, aluminium aircraft would had become an oddity, not the norm.


How can I avoid downdrafts and icing when crossing the Alps in a small airplane? let's say I need to fly from LSZL to LSZP crossing the Alps with a small airplane (C150, Piper Tomahawk,...). How many times a year I could expect to find the suitable weather conditions to do that (both VFR and IFR)?

The main issues I have identified are:

Strong downdrafts near the base of the Alps (-2000fpm). A small plane has a service ceiling of 13000ft: would it be possible to climb high enough to avoid this phenomenon?
Icing: I expect the OAT to be below zero all year, moreover ice could build up even if I'm outside the clouds. Normally small planes are not equipped with boots, or de-icing fluids systems. How can this problem be handled?

Yes, a low powered trainer can fly through tall mountains.
 It is not possible to say how often the flight may be made safely as it depends on specific weather conditions across your route of flight.

This is the same as saying a small sailboat, like a sabot, can sail to the Azores.  It is possible, and might even be safe with proper planning and good weather, but you must take care to plan the trip well every time you make it.

The number one concern I would have flying through the Alps (...or Rocky Mountains, or Sierra Nevadas...) is wind, temperature being a very close second.  A low powered trainer is pretty much at the mercy of the wind much above 5,000' and is absolutely helpless above 10,000'.  A very tame downdraft of only a few hundred feet per minute will exceed the plane's best rate of climb and could effortlessly push you into a ridge or, if you're lucky, a valley or canyon from which you may not be able to climb out.  I use the example of the Cessna 150 in Meteor Crater (elevation only 5,700' in Arizona, USA) of what can happen when an under-powered aircraft runs afoul of nature at high density altitudes.  Ice is not really an issue unless you are willing to fly through visible moisture...so...don't fly though clouds, mist, fog, etc.

I earned many of my hours flying through the Rockies in piston aircraft. The vast majority of my time in the Rockies was flying freight in cabin-class Twin Cessnas with turbocharged, geared, high displacement Continental engines and de-ice kits (a capable airplane).  Even in these planes it was common to encounter downdrafts that far exceeded aircraft performance even when using takeoff power and when lightly loaded.  The turboprops that I flew later on would fare better in that they would hold altitude (maybe even climb) at Vy and max power while carrying a load.  A Cessna 150/152, Tomahawk, or anything else with an O-235 will not do well in breezy mountain conditions.  The large mountain ranges in the US are dotted with light plane wreckage due to unfavorable weather and wind conditions.

There are things you can do to more safely traverse high terrain in a low powered plane.  I learned a few of these the hard way...

1.) Learn proper ridge crossing techniques.  There is a well defined "right way" to approach ridges if you have any doubt as to the wind conditions across the ridge.  I provide FAA documentation only because it is what I am most familiar with.

2.) Set very high weather minimums for trips through mountains.  Twice the standard requirements for VFR may be a good start, perhaps even higher.  Adhere to them during your flight.

3.) Identify alternate airports.  Know the status of the alternates (plowed?), the services provided (fuel?), and their local weather forecasts before you depart.  Take time to note distance and direction to the nearest alternates throughout your flight.  The weather can turn quickly and simply turning around and flying home is typically not an option.  Have frequencies and airport diagrams close at hand should you need an alternate.

4.) Have two realistic emergency landing spots picked out at all times.  You don't need have spots that will allow for a complete rollout, just spots that will permit you to dissipate enough energy to survive the impact. I've built the habit to scan sky, then ground, then sky when flying over rough terrain.

Landing in a field and damaging the plane may be wiser than continuing into worsening conditions.  This is a difficult realization to accept, but attempting to fly through worsening visibility, breezy conditions, and any amount of visible precipitation may kill you while landing in a field may just kill the plane.

5.) Universal advice, but particularly relevant here...if forced to land, fly all the way through the crash.  Pilots that fly their planes through a crash survive.  Pilots who become passengers do not.

If this sounds like a lot of work, it is! If this sounds overly dramatic, it isn't.  The low powered trainer was not really designed for this type of flight.  You need to take additional measures to make sure that the conditions along the route conform to the aircraft's rather severe performance limitations.
You also need to accept that the plane you describe may be quickly and thoroughly outclassed by mountain weather, weather that even a moderately more capable aircraft (C172-180hp, Piper Archer, ...) would not have a serious problem with.

This flight is doable can be done safely if planned well and flown in favorable conditions.


Are airliners' cruising altitudes we know indicated or true altitudes? Are airliners' crusing altitudes, which commonly range from 25000 to 45000 feet depending on various conditions, indicated altitudes or true altitudes? If they are indicated altitudes, what are the range of cruising true altitudes?

The altitudes are "indicated." That is the altitude shown on the aircraft's altimeter.

In the U.S. at and above 18,000 feet (known as Flight Level [FL] 180) all aircraft altimeters are set to 29.92 in. Therefore the "indicated" altitude on the aircraft's altimeter (at and above FL180) is also "Pressure Altitude." In other parts of the world "Flight Levels" (where all altimeters are set at 29.92) varies.

"True Altitude" (actual altitude above mean sea level) is not, in an operational sense, used other than a reference for weather reports, terrain, obstacle clearance, etc. It is important, but when aircraft are flying (below FL 180) their altimeters are set to a "local" altimeter setting which adjusts the "indicated" altitude to correspond closely to "true altitude." This eliminates "true altitude" as being an operational consideration.

It sounds complicated, but it really is not.  Just a bit difficult to explain.

The range of cruising altitudes varies considerably for air carrier aircraft.  It would be fair to say that the range is generally between FL290 (about 29,000 ft. msl) to FL 400 (about 40,000 ft. msl).  This varies due to ATC operational considerations, wind speed and direction aloft, and aircraft weight and performance capabilities.  There are times when some aircraft will fly a bit lower or, if the capability exists, fly higher, say FL430.


What does it mean when an airplane has the "super" call sign? What does it mean if an airplane uses the "super" designation after their call sign on the radio?

According to ICAO wake turbulence categories, it is a super-heavy aircraft capable of generating correspondingly super-strong wake vortices. Currently the only "super" aircraft are the Airbus A380 and Antonov An-225 (FAA).


Taxi to spot?? Hot spot? What is meant by this? I heard ground controller at KPHL say taxi to spot so and so?
What do they mean by this during taxi procedures.

The word “spot” just means a designated place, or part of the airport where the aircraft is to be parked and shut down.  Sometimes they are numbered.  Presuming the pilot knows where that is, the controller is simply clearing them to go there.


Why might an airliner fly a large U-turn before landing? I was on a flight1 from San Antonio, TX to Toronto and, when arriving in Toronto, the plane went quite a way past the airport, made a big U-turn, and then landed. We were coming from the west.

I thought it might have been a need to adjust for the runway, but as I said, we went quite a way past the airport, meaning after the turn we had to fly "a little bit to get back to the airport". All that even before starting the process of descending for landing (if it was just a matter of adjusting the direction for the runway, what would be the need to keep the high altitude and go so far to make the U-turn?).

Does anyone know the reason? It seems that some flights coming from the west do that move.

Air Canada 7722, October 8, 2017 (history will not persist)

(flightradar24.com) Image shows the flight's route with a final left U-turn prior to landing.

Airplanes prefer to land in a headwind. This reduces their groundspeed compared to landing with the same tailwind.

Braking distance grows quadratically compared to groundspeed. So any significant reduction in groundspeed is worth having.

Successive airplanes should all come from the same direction to land. This removes any danger of collision when a plane fails a landing and goes around into what would otherwise be oncoming air traffic. Planes also prefer to take off into  headwind, so if takeoffs are intermingled with landings (very common in a busy airport) they won't interfere with each other if they all go the same way.

The tower monitors the wind and then decides which way the airplanes should come in to land and directs landing craft to land from that direction.


Why are 737 fuselages built in Kansas? 737 fuselages are built in Wichita Kansas and are transported by train to Renton, Washington, where the plane is assembled.

Why outsource the fuselage all the way to Kansas? The cost of moving the fuselages by rail can't be trivial. Perhaps it's because of state tax credits, or maybe because Boeing bought Spirit Aerospace which was in Wichita?

Apparently the 737 used to be built in Renton: b737.org

The Boeing 737 fuselage (among other components) in Wichita for a variety of reasons

Before Boeing sold the Wichita portion of the Boeing Commercial Airplanes business to the Onex Corporation in 2005, Boeing was manufacturing structures for their aircraft in Wichita. The engineering, manufacturing, supply chain, and storage resources already existed in Wichita, so it wouldn't make sense to try to move all of that back in house at another location.
The cost to transport large components from Wichita to Renton or Everett via train is likely more economical than to manufacture and store them at the final assembly plant

On a similar vein, Boeing also uses the modified 747 Dreamlifter to transport components between suppliers and Boeing. Wichita is one of the cities that the Dreamlifter flies into, landing at McConnell Air Force Base.


What is the formula for the bank angle required for a turn in line-abreast formation? Imagine we have a line-abreast formation of aircraft, with differing airspeeds, turning around a central pivot point, like points on the radius of a phonograph record, with an equal amount time per 360 degrees of turn for each aircraft.  What is the formula for the bank angle required of each aircraft, in terms of the variables 1) turn radius and 2) time period per 360 degrees of turn?

Note that essentially the same situation applies when a slow-flying glider-- maybe even a hang glider-- and a faster, heavier glider are thermalling together and trying to stay exactly opposite each other.  Again the turn rate must be the same for each, but the turn radius is not, and the required bank angle for each might be different.  Clearly, the difference in turn radius is much more significant in this case, than in the case of high-speed aircraft turning in tight formation.

Turning Rate

All planes flying a turn in line-abreast formation are turning at the same rate $\omega$.

A standard turn is commonly defined as $\omega_1 = 3°\frac{1}{\mathrm{s}}$.

Full Circle Time Period

If planes are turning at the same rate, the time period to complete a complete circle will be the same as well.

Time period: $$ T(\omega) = \frac{360°}{\omega}$$

The time period to complete a circle at this standard turn rate is $T_1 = \frac{360°}{3°}\mathrm{s} = 120\,\mathrm{s}$.

Air Speed

Since the outer planes have to travel a longer distance to complete their larger circle in the same perios, the outer planes have to fly at a higher airspeed then the inner planes.

Air speed: $$ v = \omega r$$

Bank angle

Turn rate: $$\omega = \frac{v}{r}$$

Banking angle:  $$\tan{\theta} = \frac{v^2}{rg} = \frac{\omega^2 r}{g}$$

Gravitational constant: $$ g = 9.81 \frac{\mathrm{m}}{\mathrm{s^2}}$$

That gives the banking angle as a function of turning radius: $$\theta(r) = \arctan{\frac{\omega^2 r}{g}}$$

See the purple curve in the graph below for the bank angle in a standard rate turn (3°/s):

This curve seems to imply that one can fly a standard turn (or any other given turn rate) at any radius from 0 to infinity. Therefore I added two more curves to indicate the physical limits:

air speed (green) must be in the operating range of the plane
g load (blue) must not exceed the maximum acceptable for plane and occupants. (The correct scale for the g load is the purple scale on the left divided by 10)

And finally, the same plot but for a double rate turn (6°/s):

Practical Relevance

Typical turn radii are in the order of 1000s of meters. Typical distance (wing span) of planes in a tight formation is in the order of a few 10 meters, that is a few percent of the turn radius.

If you compare the banking angles for two planes flying in tight line-abreast formation, the banking angle difference will have a similar relative difference, that is a few percent, or a fraction of 1° in absolute terms.

[I will calculate and insert an example here, when I have the time.]

For the practical purpose of actual formation flying, pilots will give the arcus tangens a break, and fly seemingly identical banking angles.


How do ratings work with pilot certificates? Just wondering how ratings work with pilot certificates.

Let's say I get both a private pilot certificate and a commercial pilot certificate for airplane / single-engine land.

If I want to add a rotorcraft / helicopter rating onto my commercial pilot certificate for airplane / single-engine land, do I also need to get training to add a rotorcraft / helicopter rating onto my private pilot certificate for airplane / single-engine land also?

This answer applies to adding a new aircraft category onto your existing Commercial Pilot Certificate in the United States.  Consult the standards of your country's governing body for aeronautics if attempting to do this outside of the USA.

To address the second paragraph, once you hold a Commercial Pilot Certificate for the same category and class of aircraft as your private certificate, you are considered to hold a Commercial Pilot Certificate only.

In regards to the third paragraph, yes additional training will be required to fulfill the requirement of 61.63 (b) for the addition of an aircraft category rating to your CPL.  You will be required to meet the aeronautical experience requirements listed in 61.129 (c) and receive an endorsement in your logbook to take the practical exam in order to add a helicopter category to your CPL.  You will not be required to take the commercial pilot knowledge test again per 61.63 (b).


How does vertical stabilisation work? I know that similar questions are available all over the internet, including this website. However, none of the answers make full sense to me.

I'm looking for simple answer (explain-like-I-am-5 type of answer). The vertical stabiliser has rudder. It provides yaw capablity to the aircraft and I understand that completely. However, people say that if a vertical stabiliser doesn't exist, it's very hard to control the airplane, it rolls the plane out of control if not monitored.

As far as I know, the roll can be controlled using ailerons. I've heard that all wing plane design is not suggested because of lack of vertical stabiliser(s). What exactly is it that the vertical stabiliser does?

The "vertical stabilizer" (or "vertical fin") provides what is known as "weathervane stability", "directional stability", or "yaw stability".  It makes the plane act like a weathervane.  A weathervane always points into the wind.

The wind a plane "feels" is not the external, meteorological wind, but rather the "wind" created by the plane's movement through the airmass (or perhaps we might prefer to say "within" the airmass).  This apparent wind is called the "relative wind".  So the vertical fin keeps the nose of the plane pointing in the direction that the plane is actually going, i.e. in the direction that the plane is moving through the air.

Imagine driving a car at high speed on an icy lake on a day with no wind.  Can you see how a big vertical fin mounted at the back of the car would provide a "weathervane effect" that would tend to keep the car lined up with the direction it is actually moving, and would tend to prevent the car from "swapping ends" or sliding sideways?

That is what the vertical fin on an airplane does.  It's a very bad thing if an aircraft "swaps ends" or slides sideways through the air at a very large sideslip angle.  In extreme cases, there's essentially nothing the pilot can do to salvage the situation, and the plane may tumble violently out of control.  It's a misconception to say that the function of the vertical fin or vertical stabilizer could be replaced by appropriate control inputs with the ailerons.  It is true in many cases that planes with relatively small vertical fins often require the pilot to make larger rudder inputs to keep turns "coordinated", i.e. to keep the nose from swinging somewhat out of line with the direction the plane is going as it turns -- we'll save saying any more about that for some other answer.

Airplanes that lack a vertical fin must derive "weathervane stability" or "yaw stability" or "directional stability" from other aspects of the aircraft's configuration, generally having to do with the fact that more surface area is behind the center of gravity than in front of it.  For example, a swept-wing configuration generates some amount of "weathervane stability" even without a vertical fin.  Imagine putting a pair of swept wings or delta wings on a pole like a weathervane.  Can you see how, as long as the pivot point were sufficiently forward, the whole assembly would tend to point into the wind like a weathervane?  That's why hang gliders don't need vertical fins.

The question appears to contain a misconception about the relationship between yaw stability and roll stability. In fact, making the vertical fin too large actually tends to make a plane LESS roll-stable or MORE spirally unstable, so that it tends to roll away from wings-level into a steeper and steeper bank and turn.  As a plane starts to roll into a turn, dihedral and sweep (if either are present) tend to generate a stabilizing roll torque that tend to roll the plane back towards wings-level, but only if the developing turn involves some amount of sideslip.  In other words the roll-stabilizing effect of sweep or dihedral are only present if the plane is sideslipping to at least some small degree.  A large vertical fin tends to prevent sideslip, and thus makes the plane behave as if it had less dihedral or sweep. That's why planes that need lots of roll stability, like "free-flight" model airplanes that must fly with no guidance of any kind from either a pilot or a computer, rarely have large vertical fins.  Even though we don't want the plane to completely "swap ends" and tumble, or to slide sideways through the air at a really extreme sideslip angle, we do need for there to be some amount of sideslip in an uncommanded bank and turn in order for sweep or dihedral to be able to bring the plane back toward wings-level.  Likewise when a free-flight model airplane is trimmed for an intentional turn, if the sideslip were somehow completely eliminated, we'd see the bank angle start to get steeper and steeper.  If a pilot were actively controlling the airplane, he could deal with this by making an appropriate control input with the ailerons, but that option doesn't exist with the free-flight model airplane.

So other than preventing a violent tumble when the plane "swaps ends" completely, a vertical fin generally doesn't really contribute to roll stability.


Does ATC clear IFR helicopters for a visual approach if landing at a helipad on a high-rise? I'm guessing that most helipads on downtown high rises don't have any instrument approaches. If a helicopter is on an IFR to a helipad without any instrument approaches, does ATC just clear them for the visual approach, and do helicopters have their own CTAF frequency for announcing their intentions at off-airport helipads?

There are no "off-airport helipads" because a helipad is an airport. Actually, anywhere an aircraft lands is an airport as far as the FAA is concerned. It would be just like any other IFR to any other airport with no approach procedure: ATC can clear them for the visual approach if they have reasonable assurance that the weather at the airport is VFR, or the pilot can cancel IFR if they determine the weather is VFR. Public helipads have CTAFs just like any other public airports do. They can be found on helicopter charts, or in the Chart Supplement. In the attached chart snippet, you can see that the CTAFs at East 34th Street and Wall Street are 123.075 and 123.05.

One Police Plaza does not have a published CTAF because it is a private airport. Other helipads in the area are also private and not explicitly depicted.


What does 'laterally aligned' mean in this description? In the Airplane Flying Handbook there is a section on crosswind takeoffs that mostly makes sense. However, this paragraph confuses me.

  Takeoff Roll

  As the forward speed of the airplane increases, the pilot should only
  apply enough aileron pressure to keep the airplane laterally aligned
  with the runway centerline. The rudders keep the airplane pointed
  parallel with the runway centerline, while the ailerons keep the
  airplane laterally aligned with the centerline.

Laterally is an adverb meaning 'Relating to the direction to the side.'

Later on they use this image which shows the lateral axis.

When I take off in a crosswind in an airplane with nose-wheel steering the rudder pedals are used to keep the plane on the centerline. The ailerons are deflected into the wind to keep the windward wing from rising.

So what do they mean when they say that “the pilot should only apply enough aileron pressure to keep the airplane laterally aligned with the runway centerline”?

Edit: I don’t think they are referring to keeping the wings level as some commenters say. This image from the same section somewhat exaggerates the effect but ailerons are used to keep the upwind wing down.

The only meaning that I can conceive of is that "laterally aligned with the centerline" is a fancy way of saying "on the centerline"—or, at least, keeping the distance from the centerline under control, so that you don't drift off of the runway.

The paragraph seems to be describing the following technique for lateral control during a crosswind takeoff:

Use the rudder to keep the heading (the direction the nose is pointing) parallel to the runway centerline.
Use the ailerons to control the bank angle so that the airplane stays approximately over the runway centerline.

The reason the Airplane Flying Handbook uses the word "laterally" here is that the ailerons are being used to control the airplane's lateral (left-to-right) motion.

Some comments speculate that the paragraph is really saying that the ailerons should be used to keep the wings level. That doesn't make sense to me; in a crosswind, if you're using rudder to keep the nose parallel to the centerline, and you're keeping the wings level, then you'll drift downwind off the runway.


Why won't you allow someone into the cockpit while on ground? Various regulatory authorities around the world have framed strict rules prohibiting entry of passengers into cockpit. It makes some sense to not allow anyone into the cockpit (learning from 9/11), while you are flying but when on ground, what is the harm in allowing someone to enter the cockpit? The passengers are frisked thoroughly before being allowed to board the aircraft, and if you are on the ground then there is a lot of security around. So, what are the factors behind not allowing outsiders into cockpit, while on ground?

  Visitors in cockpit, four pilots lose licence

I don't agree with the strict enforcement of this rule by the DGCA (but I'm not an airline pilot so I think my opinion doesn't really count on this matter). But there is logic behind the ban - many safety-critical actions are completed before the plane has left the gate. Such actions include calculating takeoff speeds, briefing the departure procedures, and completing various checklists.

Having people in the cockpit could prove to be a big distraction when trying to complete these tasks, particularly when the time is limited anyway such as on a short turnaround.

Making a mistake before leaving the gate can definitely end in disaster. Take Emirates flight 407 in 2009. The crew entered an incorrect takeoff weight into the system. As a result there wasn't enough thrust to rotate and the A340 barely cleared the airport fence.


Just how do the underbanking and overbanking tendencies work? I understand that most GA airplanes and gliders exhibit an underbanking tendency at low bank angles and an overbanking tendency at high bank angles.

According to the Airplane Flying Handbook, chapter 3, page 3-11, if the aircraft is in steady, coordinated flight at a bank angle less than about 20 degrees, then

  This shallow bank is such that the inherent lateral stability of the airplane slowly levels the wings unless aileron pressure in the desired direction of bank is held by the pilot to maintain the bank angle.

On the other hand, if the aircraft is in steady, coordinated flight at a bank angle greater than about 45 degrees, then

  The  airplane  continues  in the direction of the bank even with neutral flight controls  unless  the  pilot  provides  opposite  flight  control aileron pressure to prevent the airplane from overbanking.

What causes these underbanking and overbanking tendencies, exactly? How do they work?

I know that when an aircraft is in a coordinated turn, the situation as experienced by the aircraft is almost identical to straight flight. As far as I know, the only significant differences are the following:

The outside wing will see a greater airspeed than the inside wing, which will mean:

The outside wing will produce more lift than the inside wing, producing a rolling moment to the inside.
The outside wing will also produce more drag than the inside wing, producing a yawing moment to the outside.
On the other hand, the outside wing will also see a shallower angle of attack than the inside wing, which will partially negate both of the above effects. I'm guessing that the lift effect will be negated more strongly than the drag effect.

The nose will see relative wind from the inside of the turn (which will have no significant effect); and the tail will see relative wind from the outside of the turn, which will produce a yawing moment to the outside.
Since the rudder is deflected towards the inside of the turn, the vertical stabilizer will produce a rolling moment to the outside.

So my questions are:

Is my understanding of the rolling and yawing forces in turning flight correct? Are there any significant effects I've missed? And how large is each of these effects—which ones are the big ones, and which ones are insignificant? And most of all, how come there's an underbanking tendency in shallow turns, but an overbanking tendency in steep turns?

I think your reasoning is correct. However, I would say that the change in lift due to effective AOA on each wing from yaw rate is an order of magnitude smaller than that from airspeed. At high bank angle, the wing loading is higher, resulting in more inward turn and decreased spiral stability. While the yaw-out moment from the drag is also increased due to relative airspeed difference on each wing, the effect is smaller since drag is smaller than lift.

Let's look at it more mathematically. Static spiral stability is dictated by:

$$C_{l_\beta}C_{n_r}-C_{l_r}C_{n_\beta}>0$$

where $C_{l_\beta}$ is roll moment due to sideslip, must be negative for a Part 23 aircraft; $C_{n_\beta}$ is yaw moment due to sideslip, must be positive for Part 23; $C_{n_r}$ is yaw-out moment from yaw rate, where, as you reasoned, should be negative due to increased drag on the up wing and reduced drag on the down wing (due to airspeed difference from yaw rate); $C_{l_r}$ is the roll-in moment from yaw rate, where, as you reasoned, should be positive due to increased lift on the up wing and decreased lift on the down wing (due to airspeed difference).

At high bank angle, there is increased load factor (at 45deg, it's 1.4G). Therefore, there is increased lift and induced drag on each wing. The moment arm to induce the moment is about the same for each. However, if you look at the first order effect from the speed increase, it's:

$$\Delta F=\frac{1}{2}\rho (V+\Delta V)^2SC_x-\frac{1}{2}\rho V^2SC_x\approx\rho VSC_x\Delta V$$

So all things being equal, the larger the coefficient, the more pronounced the effect. And since lift is larger than drag, it wins out. (I'm still hand-waving here a bit since induced drag is squared of lift, so it's more nuanced).

With this in mind, you can see that at higher bank, $C_{l_r}$ increases more readily than $C_{n_r}$, therefore leading to reduced spiral stability.


From Aerodynamic view, what is the advantage/disadvantage of the Akagi Kaman K-Max Helicopter? Here is a video showing the helicopter, the rotors are perfectly synchronized.

As there are not many such design helicopter, then my question are, is any aerodynamic weakness? What is its advantage/disadvantage of that helicopter?

It's a twin rotor design, counter-rotating: no resulting torque on the airframe and no tail rotor needing to be powered. The twin rotors do not share a common shaft, with all of the extremely complicated control mechanisms that these require.

From J. Gordon Leishman, Principles of Helicopter Aerodynamics, section 2.15:

  The design advantage of a twin rotor is that all power can be devoted to providing useful vertical lift and performance. However, the two rotors and their wakes interact with one another, producing a somewhat more complicated flow field than is found with a single rotor, and this interacting flow incurs a loss of net rotor system aerodynamic efficiency.


Twin engine helicopters: is the throttle controlled separately for each engine or together? There is usually a twist throttle on the collective for a single engine helicopter. On twin engine helicopters, does the twist throttle control it for both engines, or just for one?

Most employ separate throttles, either twist-type, on the collective or levers in an overhead quadrant.

Bell products use duel collective mounted, twist type throttles, in series. Sikorsky uses overhead levers. French SA > AS > Eurocopter > Airbus > Leonardo use levers overhead. Agusta uses overhead levers.


What is ILS 114 / 162 / 294? I am searching for airports that have ILS (not sure if there is a "law" that any airport servicing civil flights must have one).
So I googled around and found this nice site http://www.azworldairports.com.
So I've been looking at airport in Vienna and in airfield section there is following:

Runway 1: Heading 11/29, 3 500m (11 482ft), 75, ICAO Cat. I, 3B, Aircraft size max: E, Rwy 11, ILS 114, Lighting: 11 CAT 1/PAPI, No Restrictions, Rwy 29, ILS 294, Lighting: 29 CAT 1/PAPI, No Restrictions
Runway 2: Heading 16/34, 3 600m (11 811ft), 75, ICAO Cat. I, 3B, Aircraft size max: E, ILS 162, Lighting: CAT III B/PAPI, No Restrictions

What exactly is ILS 114 / 162 / 294?

That's the ILS heading to the runway.

Based on how runways are numbered, runway 11's heading will be somewhere between 105° and 114°, 114 nails it down.


How to calculate or design glide ratio? Was interesting to watch the explanation about glider here, especially about the glide ratio. Glide ratio is defined as the ratio between altitude when it start gliding (Y-axis) to the distance it can reach until the altitude reach zero (X-axis), as shown in the picture 2. Gliding is a descending, opposite of climbing, which is ascending. All airplanes are designed to be able to glide to anticipate the worst case when the engine is failure.

There are many discussions how to calculate an airplane when ascending, explains the relation of wing area, wing ratio, airplane load, initial speed (velocity), and the power it requires to meet the ascending rate. Then my question is, how do I bind such that information when calculating the glide ratio/distance?

Edit:
I believe the weight of the airplane contributing the glide distance (ratio) it can reach. Just consider two identical airplanes (say it Cessna 172), one is fully loaded and another one is not loaded at all (except the pilot, of course). They fly at the same speed and turned off the engine at the same time.

Also consider two airplanes (also Cessna 172) with exactly same weight and load, but fly at different speed and then turned off the engine at the same time.

From both above illustrations, we know their momentums are different. Is not the momentum contributing to the glide distance (ratio)?

One simple way is to compare thrust requirement for level flight at Vbg, where lift to drag ratio is optimal, to the weight of the plane.  This ratio of pounds of thrust, which is equal to pounds of drag in steady state level flight, to the weight of the plane should give a good approximation of the glide ratio.  Glide ratio is how much altitude do I give up to move how far forward.  The altitude is the power source.  How far forward you move is dependent on drag.

So an 1800 lb Cessna would require 200 lbs of "thrust" to glide 9:1.

Now to design for it, speed is a critical factor in selection of wing type and loading.  This is the albatross vs eagle consideration.  Higher speed cruisers favor the albatross.


In which cases the lift distribution is not elliptical? (i.e. e≠1) I understood that Oswald coefficient doesn't modify the induced drag (i.e. =1) if the lift distribution is elliptical.
When is the lift distribution not elliptical? What are the physical or ideal causes?

When is the lift distribution not elliptical?

The distribution is non elliptical basically always, you have to struggle quite a lot to achieve an elliptical distribution.

As far as I know only the Spitfire managed to decently approximate the elliptical distribution, and even then, the unavoidable presence of the fuselage had its consequences.

  What are the physical or ideal causes?

Ideal? I think you are confusing what is ideal here. The ideal case is the elliptical distribution, since it gives you the minimal induced drag for equivalent lift.

As basic theory goes, you can have an elliptical distribution with an elliptical wing (is a consequence of the so-called lifting-line theory).


Could aircraft already do a safe auto-takeoff with todays equipment? If a plane can already autoland and stay aligned while roll-out by itself, on a CAT-3 ILS-Approach, I asked why there is no auto-takeoff-function on todays autopilots.

Because it should be technically possible and much safer than a hand flown takeoff.

For the technic:
When on the runway, the pilot presses an auto-take-off button. The plane stays aligned by following a normal CAT-3 Localizer. Takeoff-Thrust is made with autothrottle. At Vr, the plane rotates by itself, smoothly,and activates VNAV and LNAV and follows the SID. It is also possible to implement a live wind sensor to dynamically update V-Speeds.
For safety:
In case of an emergency during take-off, a computer take-off would be more safer. The plane knows the speed and runway length. So in case of an emergency, it knows if it's below V1 and also if the available runway length is sufficient for a safe rejected take-off. A computer always has a lower reaction time than humans and they can response faster. A computer can immediately decide wether to take off or reject based on lots of live data. A (rejected) take-off performed by a computer should be times safer.

So, why has an autotake-off-function not been developed yet? And what arguments would speak against an auto-take-off function?

--
There is not an answer to my question here: On modern commercial airliners, how much of the flight could be fully taken care of by the auto pilot? as stated below. I want to know what reasons, if there are any, speak against auto-take-off.

With some refinement and programming, the technology is easily there, sure; it just needs a few million dollars of design and certification costs for very little benefit.

The main reason we have autolands is because it saves airlines money, by allowing the plane to land safely in minimal visibility instead of diverting to another airport. Aircraft taking off don't have this problem as they can do it in just about zero visibility. If there is no commercial incentive, the reality is it is not going to happen. Only when pilots are considered surplus to requirements will this ability be developed in earnest.

There could be an argument made that it should be done for safety's sake, but I don't buy it. Pilot errors made on the takeoff run, resulting in an accident are incredibly rare. Maybe an auto takeoff could prevent a few tailstrikes but I can't see much more benefit.

Whenever you introduce something new you have to think long and hard about the ramifications of it. There's a whole discussion to be had on how rejected takeoffs would work - generally speaking, you do not want automation doing something that the pilots aren't expecting. It is sometimes better to take an issue into the air than take the risk of a high-speed RTO even under V1, how will the computer judge that when there are few hard and fast rules for it? Do you trust the human programmers to account for every single scenario? Then there's pilot competency, how do they keep their skills up when they could go months without flying the aircraft? If they are in the habit of delegating their decision making to the computer, will they be able to handle the heat in that career-defining moment when the computer fails and it's all on them?