Crimes committed on board I know a similar question was asked here before, but there is a difference:

Let's say person X is on a flight from Pakistan to Canada on PIA (national carrier of Pakistan). The aircraft lands at, say, Toronto Pearson Airport.

From what I gather after reading the Tokyo Convention, the aircraft is no longer in flight once the airplane doors have been opened for disembarkation.

If an offence occurred on the airplane once the doors have been opened for disembarkation, which country is responsible for prosecution? The country where the aircraft is registered or the country where the plane has landed?

Once the doors have been opened, it's a pretty clear case: the crime happens on some sovereign soil, and that country is responsible. They are also most likely to get custody of the criminal, which as described in the other answer is a large part of who prosecutes.


Is there a reason or code behind the Cessna model numbers? Is there a story behind how Cessna model numbers were created?

E.g., models 170, 172, 180, 182, 206, 310, 336, etc.

There is no theme, but like some cars or mobile phones, there's a logic to it. A higher series (200 vs. 100) is bigger, a higher sub-series (180 vs. 170) is more powerful, the P and T are pressurized and turbo, and so on.

The no theme is supported by the Apr 1981 issue of Flying Magazine, where it is confirmed by the Marketing SVP of Cessna (p.58).

Re: what about the last digit, e.g., 180/182/185?

"Engineering numbers" mean internal numbers with no marketable meaning, just like the first two digits. My guess is that there were 181, 183, and 184 designs on paper at one time.


How does ATC handle different kinds of emergencies? This question deals with the pilot procedures for declaring an emergency.

I wonder how ATC in the US handles different kinds of emergency or quasi-emergency situations, such as:

MAYDAY
PAN PAN
Minimum Fuel
Medivac
etc

Are there multiple levels of priority handling inside ATC, and how do they communicate priority handling from controller to controller?

FAA Order JO 7110.65W - ATC Procedures, Chapter 10 outlines how ATC should handle procedures for emergency situations.

In the very first section though, it says:

  10-1-1(d)
  Because of the infinite variety of possible emergency situations, specific procedures cannot be prescribed. However, when you believe an emergency
  exists or is imminent, select and pursue a course of action which appears to be most appropriate under the circumstances and which most nearly conforms to the instructions in this manual.

So, for Mayday and Pan-Pan, it says in 10-1-1(a):

  A pilot who encounters a Distress condition should declare an emergency by beginning the initial communication with the word “Mayday,” preferably
  repeated three times. For an Urgency condition, the word “Pan-Pan” should be used in the same manner.

The use of Mayday and Pan-Pan declares an emergency, but doesn't tell ATC about the nature of that emergency. Therefore just saying those words doesn't trigger any particular method for handling the emergency other than probably the controller offloading other traffic and giving you priority handling. It'll probably also trigger a clearing of the airspace around you, and if you are on final or near an airport, a ground hold.

For Medevac:

2-1-4(b) outlines:

  Provide priority to civilian air ambulance flights (call sign “MEDEVAC”). Use of the MEDEVAC call sign indicates that operational
  priority is requested. When verbally requested, provide priority to AIR EVAC, HOSP, and scheduled air carrier/air taxi flights. Assist the pilots of
  MEDEVAC, AIR EVAC, and HOSP aircraft to avoid areas of significant weather and turbulent conditions. When requested by a pilot, provide notifications to
  expedite ground handling of patients, vital organs, or urgently needed medical materials.
  NOTE−
  It is recognized that heavy traffic flow may affect the controller’s ability to provide priority handling. However, without compromising safety, good judgment must be used in each situation to facilitate the most expeditious
  movement of a MEDEVAC aircraft.

For Minimum Fuel

2-1-8 Outlines:

  If an aircraft declares a state of “minimum fuel,” inform any facility to whom control jurisdiction is transferred of the minimum fuel problem and be alert
  for any occurrence which might delay the aircraft en route.
  NOTE−
  Use of the term “minimum fuel” indicates recognition by a pilot that his/her fuel supply has reached a state where, upon reaching destination, he/she cannot accept any undue delay. This is not an emergency situation but merely an
  advisory that indicates an emergency situation is possible should any undue delay occur. A minimum fuel advisory does not imply a need for traffic priority. Common sense and good judgment will determine the extent of assistance to be given in minimum fuel situations. If, at any time, the remaining usable fuel supply suggests the need for traffic priority to ensure a safe landing, the pilot should declare an emergency and report fuel remaining in minutes.

(Emphasis mine)

Really you should read through the entire (long) document to see how ATC is supposed to behave for certain situations. Chapter 2, Section 1 has a lot of "emergency" situations, but most of it boils down to giving priority and assistance that the pilot asks for.


What is the difference between ADS-B UAT and ADS-B ES? Why would an owner decide to put in an ADS-B UAT transceiver versus an ADS-B ES transceiver?  What are the advantages and disadvantages of both systems?

ADS-B UAT operates on 978 MHz and are available for aircraft that operate below 18,000 FT MSL.  UAT transceivers can display aviation weather products (FIS-B) as well as traffic from ground radio stations (TIS-B).  The airplane must be in a coverage area for TIS-B services.

  TIS-B is intended to provide ADS-B equipped aircraft with a more complete traffic picture in situations where not all nearby aircraft are equipped with ADS-B Out. - AIM 4-5-8

Aviation weather products available over FIS-B through ADS-B UAT transceivers

ADS-B 1090ES operates on 1090 MHz and is required for aircraft operating above 18,000 FT MSL.  The information sent over a Mode S transponder is greater and is called an "extended squitter".  These aircraft will be able to display traffic directly from other ADS-B equipped aircraft and those with Mode S transponders without the need to rely on ground based systems.  FIS-B is not available to these transceivers.

The picture below illustrates where 1090ES and UAT are allowed / required for aircraft after the ADS-B mandate in 2020.

References:

Aeronautical Information Manual 4-5-7 thru 4-5-9
Advisory Circular 90-114A


How do you check the correct operation of the rudder when it's tied to the nose wheel? Preflight checklists often contain the item

Flight controls: Free and correct

However, if the rudder is tied to nose-wheel steering, is it even possible to check if the rudder is correctly connected (unless have a rear window and can see the rudder during taxi)?

Every small airplane that I've flown that uses the rudder pedals for nose wheel steering uses bungee cords or springs so that they will stretch when pushing the pedals without the aircraft moving.  This allows the pedals to move without requiring the nose wheel to do so as well, and you can check them in the normal manner.

Larger airplanes that use the rudder pedals for nose wheel steering have a method of turning the nose wheel steering on and off, so the check could be done before the steering is engaged.  That being said, most larger aircraft do the control check during the taxi (that's when most airliners are doing it) and there is nobody out there to make sure that the rudder is actually moving the correct direction.  In my airplane, the response for the flight controls is "free and self-centering" (since we have hydraulic flight controls) and we don't verify the actual direction of rudder movement.  That's a maintenance function.


Why is radio communication still used? Why is radio still the method of communication from the ground to air? If i'm not mistaken, cellular services should be much better in quality and reliability

Cellular communication has multiple issues:

When a plane is up more than a few thousand feet, a cell phone would see, and try to talk to, multiple cell towers at once.  At best, this is inefficient and overloads the cell network.  At worst, the network can get confused and drop calls.  (not something you want when trying to get ATC directions)
When a plane is moving rapidly, it will change cell towers frequently.  This has the same problems as above.
Cell communications is designed for Person-to-Person during a single call.   Aviation radio is designed so that everyone can hear everyone else's communications.  Even if an ATC instruction is not specifically for me, I can get a mental picture of what other planes are nearby and what they are doing.  This is not so easy with cellular.
In many rural areas, cell phone coverage is limited.


Would injecting water into a jet engine’s exhaust increase velocity? Can high pressure mist of water be sprayed into jet engine exhaust, to create steam, to increase velocity? Would the steam generated from high pressure water being injected into the jet engine exhaust increase velocity?

Spraying water into the exhaust stream will cool down the exhaust flow. The energy needed to heat and evaporate the water needs to come from somewhere, after all. The cooler and denser exhaust flow will slow down, so its impulse will become lower, reducing thrust. While the mass flow will go up, its speed will be reduced. Since water enters the flow as a liquid and leaves the nozzle as a gas, its evaporation enthalpy is irretrievably lost and removes energy from the exhaust stream. The slightly higher mass flow in combination with a lower speed will result in a lower impulse.

If you spray water into the intake flow (or after the first few compressor stages), the same evaporation enthalpy will allow a higher mass flow in the intake, so a higher mass flow in the combustion chamber can be achieved. Also, the cooling of the intake air allows to add more fuel in the combustion process, so more thrust can be created. Of course, this is bought with higher fuel flow.


Am I required to obtain a student license before a sport, recreational, or private one? I want to double check if my first step in obtaining a sport, recreational, or private license is to obtain a student license.  I'm assuming student license always comes first, but want to make sure.  :-)

I want to make sure that isn't a less expensive way to go than this -- jumping into a more intensive program to go "straight" to the higher level licenses.  Want to make sure getting a student license first doesn't financially waste some of the classes, training, or flight hours you pay for -- by them not counting toward the higher level licenses -- where if you had done it differently you would have saved money.

I'm not talking about less learning, just how it's done.  (Making sure high enough licensed instructors, right classes, etc.)

As an addition... Do you jump through student, sport, recreational, to private?  Or, do you go from student which whichever of these you want?

A student pilot certificate is just a medical certificate printed on yellow paper instead of white paper and with endorsement templates for soloing printed on the back.  Other than that presentation difference it is no different than the medical exam a certificated pilot takes for whatever class medical you apply for.  The fee for this varies by examiner and may set you back $75 or so, but that (and being able to pass a medical) is the only barrier to entry.  There is no flight training or knowledge requirement to get this certificate.

Once you have a student pilot certificate / medical you have one of the requirements to solo and can train directly for any of the sport, recreational or private pilot certificates.  You'll want to focus on sport or private training, as pretty much no one pursues recreational certificates.


Does the NTSB and other investigative agencies charge airlines for investigations? Does an airline have to pay the investigation team? For example the NTSB? And if Boeing or Airbus participate in the investigation, do they also charge the airlines?

In the United States, no, the airline does not pay the NTSB or the FAA for accident investigations. This is considered a public service and is paid for by tax funds.

That doesn't necessarily mean that they won't pay for anything. For example if the NTSB has to remove wreckage to examine it, they will often have the insurance company pay for the removal and transport. This is especially true in GA investigations where the responsibility for moving the wreckage (after the NTSB says so) is up to the owner/their insurance.

Whether or not Boeing/Airbus/XXX charges airlines would be another matter that is probably outlined in contracts between the airlines, the aircraft leasing company, and the manufacturers.

Note that NTSB may involve any number of parties, for example they would have Boeing for the airframe, GE for the engines, Honeywell for the avionics/sensors, and representatives from other companies/groups (like the Airline Pilots Association) as they see fit. NTSB has manufacturer representatives for the bigger parts, and may ask for additional help from other smaller providers. This is done under the NTSB "party system" which is by invitation and does not compensate the parties for participation.

So as far as accident investigation goes, no, airlines/manufacturers don't pay for that directly.


What are some examples of warning areas and restricted areas? Can you please give me some examples of warning and restricted areas?

How can an aircraft enter these areas? What are the procedures you have to follow before entering them?

I'll provide information for the US airspace. However many countries, ICAO members, will have similar concepts and procedures.

Short answer

You are not required to follow any procedure for entering a warning area or an inactive restricted airspace. In the latter case, you need to ensure the area is actually inactive. A safe practice is to contact the controlling agency of the area prior to enter any warning or restricted one.

The longer answer below develops a bit around special use airspaces which encompass warning and restricted airspaces among other. You'll also find two examples of these areas.

Context

The airspace over the US is open to navigation, a part of this airspace benefit from services provided by air traffic control (ATC), e.g. safe separation and traffic information.

This controlled airspace includes airport areas and airways, and other areas of interest. It is is ruled by air regulations relative to airspace classes. In the US these regulations are found in document 94 CFR 91.

source)

Some limited areas, that may be permanent or temporary, can be prohibited or restricted. Together they constitute the special use airspaces (SUA)

Special use airspaces

SUA (Wikipedia):

  Special use airspace includes: restricted airspace, prohibited
  airspace, military operations areas (MOA), warning areas, alert areas,
  temporary flight restriction (TFR), national security areas, and
  controlled firing areas.

The SUA are repertoried by the FAA: SUA Web site.

You may search by name or scan the map. R denotes a restricted airspace, and W a warning area.

More on SUA: Course Notes, Dennis Seals, FAA

Your question is limited to warning areas and restricted airspace.

Restricted airspace

Wikipedia:

  Restricted areas denote the existence of unusual, often invisible,
  hazards to aircraft such as artillery firing, aerial gunnery, or
  guided missiles. Penetration of restricted areas without authorization
  from the using or controlling agency may be extremely hazardous to the
  aircraft and its occupants.

See also chapter 3−4−3. Restricted Areas of the FAA-AIM.

Entry: Forbidden when active, subject to ATC clearance on a case by case basis.

For areas that have a scheduled activity, times of activation are published in the AIP. When inactive, a R-area is just a like any other location of the surrounding airspace class. When active it is just forbidden to enter it (albeit FAA may deliver specific clearances if solicited).

For VFR flights, contacting ATC prior to entering an inactive restricted area is not mandatory per regulations, but is a good practice regarding safety. IFR flights under monitoring of the ATC, will not be authorized to enter an active restricted area.

Wikipedia:

  Restricted airspace zones may not be active at all times; in such
  cases there are typically schedules of local dates and times available
  to aviators specifying when the zone is active, and at other times,
  the airspace is subject to normal VFR/IFR operation for the applicable
  airspace class.

Activity time may happen unscheduled for some R-areas. A schedule cannot be published, in this case a NOTAM is used to inform airspace users.

Wikipedia:

  A few zones are activated by NOTAM; an example is R-2503D over Camp
  Pendleton in southern California, between San Diego and Los Angeles.
  This particular zone, beginning at 2000ft above sea level over most of
  southern Camp Pendleton, can only be active for a certain number of
  days per year, thus allowing small planes to fly a direct route over
  land between the two metro areas instead of being diverted offshore or
  into mountainous terrain further inland.

Example: Restricted areas R-2501 around the Twentynine Palms Marine Corps Air Ground Combat Center:

GlobalSecurity.org:

  The Twentynine Palms Complex is located in the Southern California
  desert approximately 115 NMI northeast of Los Angeles, CA. The
  Twentynine Palms Complex provides a vast land and restricted airspace
  (R-2501) area for live ordnance employment and combined arms training
  of infantry units, armored vehicles, artillery, and air support.

  The complex includes the following instrumented area: R-2501E

  The following are training, and Military Operating Areas (MOAs)
  associated with the Twentynine Palms complex:

  R-2501N
  R-2501W
  R-2501S
  Bristol MOA
  Sundance MOA
  Range Training Areas (RTA)

Description of R-2501N from Order JO 7400.8S:

R-2501N Bullion Mountains North, CA
Boundaries.
Beginning at lat. 34°30'00"N., lon g. 116°26'23"W.;
to lat. 34°36'00"N., long. 116°28'03"W.;
to lat. 34°40'30"N., long. 116°29'43"W.;
to lat. 34°43'00"N., [...]
Designated altitudes. Unlimited.
Time of designation. Continuous.
Controlling agency. FAA, Los Angeles ARTCC.
Using agency. Commanding General, Marine Corps Base, Twentynine Palms, CA.

This area around a large military complex is active (restricted) 24x7, at any altitude. A pilot who wants to enter this area for some reason needs to contact either the controlling agency (Los Angeles ARTCC) or the using agency (Marine Corps Base).

Warning area

Chapter 3−4−4. Warning Areas of the FAA-AIM.

  A warning area is airspace of defined dimensions, extending  from
  three nautical miles outward from the coast of the U.S., that contains
  activity that may be hazardous to nonparticipating aircraft. The
  purpose of such warning areas is to warn nonparticipating pilots  of
  the potential danger. A warning area may be located  over domestic or
  international waters or both.

Entry without specific clearance, but can be hazardous. Contacting ATC prior to entering a warning area is not mandatory per regulations, but is a good practice regarding safety.

Example: Pacific Missile Range Facility (PMRF) NS Barking Sands.

GlobalSecurity.org:

  The area surrounding Kauai is divided into warning areas with W-186
  and W-188 controlled by PMRF. The Fleet Area Control and Surveillance
  Facility (FACSFAC) controls W-187, 189, and 190. Space, air, and
  surface tracking are accomplished from PMRF precision-tracking radar
  sites at elevations of 75 ft., 1700 ft., and 3800 ft. These are
  supported by radar systems operated by agencies external to PMRF.

Description of W-188 from Order JO 7400.8S:

W-188 Hawaii, HI
Boundaries. Beginning at lat. 21°58'19"N., long. 159°48'45"W.;
to lat. 21°58'27"N., long. 159°59'50"W.; [...]
Altitudes. Surface to unlimited.
Times of use. Continuous.
Controlling agency. FAA, FAA, Honolulu Control Facility.
Using agency. Commander, Pacific Missile Range Facility, HI.

More:

Related question: Can a pilot fly through a restricted area while flying on a Victor Airway?


Sport pilot upgrade to private pilot I have a sport pilot license and fly my own SLSA (Special Light Sport Aircraft). I have all the required logbook hours signed off by my CFI for the PPL and 120 hours as PIC plus 80 dual student hours. Once I pass the PPL written test and obtain a 3rd class medical, would I be required to take a full oral test and check ride to obtain a PPL?

Notes:

SLSA: Special Light Sport Aircraft
CFI:  Certificated Flight Instructor
PIC:  Pilot In Command
PPL:  Private Pilot License

EDIT: Thanks for responding. I do have 3 night flying hours + 3 hours under the hood. I did all the required private pilot flying and ground school hours before deciding to go the light sport route. I'm thinking about about getting the private pilot license if and when the 3rd class medical is eliminated as a requirement. So, my question is - what would I be tested on for the private pilot checkride? Or would a checkride even be required?

I believe PPL also requires some night flying time (at least the 141 school I am at does). I believe Sport Pilot License is not valid at night so you may have to gain some night landings and hours to go for the check ride as well. However I do see that you have all the hours signed off so I will assume this includes night hours.

But AFAIK you will need to pass the written, oral and check ride to get the PPL.

As per your updates this is what you will be checked on for your check ride. Its a bit dated but this video has some nice coverage on what you may get on your oral exam. If you have the Jeppesen study materials you should have some good lists of what you will find. I did find this in the FAR

  §61.103   Eligibility requirements: General.
  To be eligible for a private pilot certificate, a person must:

  (a) Be at least 17 years of age for a rating in other than a glider or balloon.

  (b) Be at least 16 years of age for a rating in a glider or balloon.

  (c) Be able to read, speak, write, and understand the English language. If the applicant is unable to meet one of these requirements due to medical reasons, then the Administrator may place such operating limitations on that applicant's pilot certificate as are necessary for the safe operation of the aircraft.

  (d) Receive a logbook endorsement from an authorized instructor who:

  (1) Conducted the training or reviewed the person's home study on the aeronautical knowledge areas listed in §61.105(b) of this part that apply to the aircraft rating sought; and

  (2) Certified that the person is prepared for the required knowledge test.

  (e) Pass the required knowledge test on the aeronautical knowledge areas listed in §61.105(b) of this part.

  (f) Receive flight training and a logbook endorsement from an authorized instructor who:

  (1) Conducted the training in the areas of operation listed in §61.107(b) of this part that apply to the aircraft rating sought; and

  (2) Certified that the person is prepared for the required practical test.

  (g) Meet the aeronautical experience requirements of this part that apply to the aircraft rating sought before applying for the practical test.

  (h) Pass a practical test on the areas of operation listed in §61.107(b) of this part that apply to the aircraft rating sought.

  (i) Comply with the appropriate sections of this part that apply to the aircraft category and class rating sought.

  (j) Hold a U.S. student pilot certificate, sport pilot certificate, or recreational pilot certificate.

In regards to section H you have to pass the practical for the PPL specifically so it would seem you will be retested. Although part J would allude to the fact that your SPC comes in here it seems that it just counts in place of a student pilot certificate.


Is it normal to choose a left or right pattern based on the wind direction? I fly at Las Cruces International (KLRU) which is in an area with high winds (20 knots or more).  My flight instructor wants me to fly the traffic pattern according to the crosswind direction on takeoff.  So if the crosswind on take off is from the right he wants me to fly right traffic, if the crosswind is from the left he wants me to fly left traffic.

I understand the rationale for this.  When you are flying into the wind you have more airspeed and if you suddenly turn out of the wind you lose airspeed and risk stalling.  In fact we have had accidents here where a pilot turned out of the wind on takeoff and stalled because they suddenly lost airspeed.

I have never heard of any guidance in my ground school courses on changing the traffic pattern based on crosswind direction.  So my question is how would an FAA Designated Pilot Examiner interpret me using a non-standard traffic pattern if I fly the traffic pattern according to the crosswind direction?  Could I get in trouble for flying a non-standard pattern even though it would technically be safer to fly into the wind?

It is NOT normal to pick the pattern (right/left) based on crosswind.

As JScarry pointed out in a comment, "At a non-towered field you fly the published direction. If none is published, you fly left traffic. At a towered field you fly whichever direction they tell you."  That's how you pick the pattern.

  When you are flying into the wind you have more airspeed and if you suddenly turn out of the wind you lose airspeed and risk stalling

This is flat out wrong.

To prove this, find a day where the winds aloft are high, then practice flying constant bank angle circles at altitude while at Minimum Controllable Airspeed.  If your theory is correct, you should consistently stall whenever the nose of the plane is pointing downwind.  (Hint: it won't)

For a second experiment, on a day with a strong crosswind, watch your airspeed indicator as you make your first turn after take off.  Try turning both into the wind and away from the wind. (i.e., try both a left & right pattern).  The airspeed indicator shouldn't show any difference.

Once you are in the air, the only speed your wing cares about is airspeed.  The wing doesn't know if it's a headwind or a tailwind.


Does turbulent flow have boundary layer ? Does separated flow have boundary layer? I have a little confusion between turbulent flow and separated flow. Consider a flow over a typical airfoil: Does turbulent flow region have boundary layer ? Does separated flow region have boundary layer ?

Yes.
There are boundary layers (BL) in laminar flow, turbulent flow, and the
transition between the two.

"Flow separation occurs when the boundary layer travels far enough against an
adverse pressure gradient that the speed of the boundary layer relative to the
object falls almost to zero. The fluid flow becomes detached from the surface of
the object, and instead takes the forms of eddies and vortices."

From: "Flow Separation"
https://en.wikipedia.org/wiki/Flow_separation

Note that the shear stress at the wing surface drops to zero (or very close to zero) after the BL separates.

It is also possible for BL to re-attach to the wing surface after an initial separation. In that case the shear stress returns to a non-zero value.


Where can I get full audio cockpit recordings of all four flights involved in the 9/11 attacks? First of all, this is a question specifically asking about the September 11th, 2001 attacks. It is not focused on NTSB or other accident investigations in other countries. If you think it is, please explain your reason.
I have always been curious to know how people reacted to that terrible day, and if I remember correctly, there was a thirty-one-minute recording from flight 93 that started with someone saying there was a bomb on board up until the crash.
I guess the main reason I am so focused on sound is because of something I am going to explain to you all. I am a totally-blind user who uses screen reader technology and accessible web sites to brows. Since I cannot obtain visual information and expressions, my next source of information is how things sound. It is frustrating to not have this information. Someone could tell you that this or that happened, and it looked horrific, but if you can't see it, how do you know? Maybe some people would say that it was a blessing that you didn't have to see such things, but still, I feel like I'm missing out on something. Sounds of horror, of grief, all of those can be just as traumatising to hear as one would see an image. I have spent numerous hours on YouTube, trying to find stuff to add to my audio memorabilia of 9/11, because as we move through history, I want people of the future to know how everything played out from beginning to end, what people endured, how many people were killed, hurt, and willing to risk their lives to help rid the bad guys. Most importantly, I want them to experience all of this without the ability to see what's going on. If you can hear the recordings, you should be able to make pictures based on all of your senses, and you'll be able to make appropriate emotional responses.
Also, a friend of mine inspired me to do all of this because she had a former acquaintance of hers, who is no longer her friend tell her that 9/11 never happened, that it was all a conspiracy. So I vowed to help her out by obtaining as much proof as I could by making a file containing as many audio recordings detailing the events of that day.
I have heard that the NTSB is exempt from releasing these audio recordings even with the FOIA, but I believe that if you can approach an attorney, you can circumvent this exemption by claiming that such recordings must be available for historic reasons. I don't know if they will release it twenty-five years later, fifty years, seventy-five, or a hundred years from now.
And yes, there has been evidence of CVR recordings being leaked into the public, which is like finding a rare piece of jewellery since they are scarce.

The short answer: you can't. Federal law prohibits the release of CVR audio, though transcribed excerpts (if they are relevant to the investigation) are made publicly available once the accident report is released.

See 49 USC 1114(c):

  Cockpit Recordings and Transcripts.—(1) The Board may not disclose
  publicly any part of a cockpit voice or video recorder recording or
  transcript of oral communications by and between flight crew members
  and ground stations related to an accident or incident investigated by
  the Board. However, the Board shall make public any part of a
  transcript or any written depiction of visual information the Board
  decides is relevant to the accident or incident— (A) if the Board
  holds a public hearing on the accident or incident, at the time of the
  hearing; or (B) if the Board does not hold a public hearing, at the
  time a majority of the other factual reports on the accident or
  incident are placed in the public docket.


Why do high-speed water impacts / ditching usually result in structural loss of the airframe? Plywood sheets can penetrate tree trunks unscathed - when pushed by hurricane or tornado winds.  Why wouldn't an airplane fuselage, wings and tail behave the same way impacting ocean water at a steep angle at 300-500 mph?  That is, penetrate and remain intact. I have seen a lot of supposition written about this which seems based on common sense, but common sense might be misleading.  Has  the outcome of such an event ever been demonstrated?

Plywood sheets can penetrate tree trunks unscathed

The plywood isn't unscathed by the process

  Why wouldn't an airplane [be unscathed by] impacting ocean water at a steep angle at 300-500 mph?

The aircraft will not travel at that same speed underwater. That means that a considerable force is applied to the aircraft to decelerate it in a short distance. That force greatly exceeds what the structure was designed for.


If the updated MCAS software needs two AOA sensors, doesn't that introduce a new single point of failure? Regarding the 737 MAX story, the New York Times writes:

  "Boeing’s software update would require the system to rely on two
  sensors, rather than just one, and would not be triggered if the
  sensors disagreed by a certain amount, according to the three people.
  Given that the 737 Max has had both sensors already, many pilots and
  safety officials have questioned why the system was designed to rely
  on a single sensor, creating, in effect, one point of failure [emphasis mine]"

Now I understand that this avoids a False Positive, when one erroneous sensor triggers the MCAS.

But, considering the opposite situation, doesn't this update introduce a new single point of failure, a False Negative, when a stall should be counteracted with MCAS but it isn't, because only one sensor detects it?

(Or if not, what am I missing here? Is it that a faulty sensor fails in a certain way and will not read normal AOA erroneously?)

Noting that the details of the MCAS update are yet to be publicly confirmed by Boeing - no I don't believe you are missing anything.

MCAS was meant to be a system that only kicked in when the pilots were letting the situation get out of hand. It was to aid in stall prevention, but does not do anything the pilots can't (as long as their situational awareness would allow). In a million flights MCAS would not be used once unless there were other serious difficulties at play.

In such a system it is much better to have a false negative than a false positive. A false negative means that the aircraft doesn't change anything, and continues to follow the pilot commands. A false positive means... well, it looks like there are 2 crashes that demonstrate what happens.


Does a multi-engine ATP with single-engine commercial privileges provide single-engine instrument privileges? Does a multi-engine ATP with single-engine commercial privileges provide single-engine instrument privileges?

I received my ATP certificate recently, and the back of my FAA certificate reads as follows.

AIRLINE TRANSPORT PILOT
  AIRPLANE MULTIENGINE LAND
  ...
COMMERCIAL PRIVILEGES
  AIRPLANE SINGLE ENGINE LAND
...

I left out the specific type ratings and limitations as noted by ....

The ATP supersedes an instrument rating, but the ATP is for the multi-engine category. Shouldn't the certificate reflect an instrument rating in the single-engine category?

The changes to my certificate were completed in IACRA and I have had part of a rating inadvertently removed before using the IACRA system.

Note this is my interpretation of part 61. Double check with the FSDO for a more legally biding answer.

Since the Instrument addon is by category, not class, aka Instrument Airplane, or Instrument Rotorcraft, the ATP Multi-Engine Airplane, counts for Instrument Airplane for the Commercial Single.


What is an ATC clearance? Does a VFR flight have to get a ATC clearance? 1)
Do all flights have to get an ATC clearance to fly in controlled airspace such as class C airspace? I know that IFR and VFR flights are provided with ATC service in class C airspace, but I am not sure that receiving ATC service means an ATC clearance must be obtained. And if so, should VFR aircraft also get an ATC clearance like an IFR clearance that is given to a pilot before take-off including clearane limit, route, level, squwak, etc?

2)
What is an ATC clearance? 'ICAO Annex 11' defines an ATC clearance as an "Authorization for an aircraft to proceed under conditions specified by an air traffic control unit." And, also states that an "ATC clearance shall indicate a) aircraft identification as shown in the flight plan, b) clearance limit, c) route of flight, d) level(s) of flight for the entire route or part thereof and changes of levels if required and e) any necessary instructions or information on other matters such as approach or departure manoeuvres, communications and the time of expiry of the clearance."

I think it refers to the IFR clearance given to pilot before take-off.

Does it mean that an ATC clearance always includes all these items such as route or level? If the ATCO instructs a VFR pilot to maintain 5,000ft for separation with IFR, is it just instruction because it doesn't include a clearance limit and route?

In the same vein, is a take-off clearance a type of ATC clearance? It doesn't include some items such as route. But the definition of an ATC clearance states that "The abbreviated term “clearance” may be prefixed by the words “taxi,” “take-off,” “departure,” “en route,” “approach” or “landing” to indicate the particular portion of flight to which the air traffic control clearance relates."

All IFR flights require a clearance in controlled (class A-E) airspace. Clearances aren't available in uncontrolled (class F-G) airspace.

VFR flights in certain airspace (ICAO: class B-D, FAA: class B only) require a clearance and may be referred to as CVFR. This clearance will be much simpler than an IFR one, though.

The purpose of an IFR clearance having a limit, route and altitude is so ATC knows what the plane will do if communication is lost and therefore can maintain proper separation of other aircraft. This detail isn't required for a CVFR clearance because a VFR pilot is required to be able to provide his own separation anyway, so the VFR lost comms procedures are much simpler.

ATC can amend a clearance, in which case they only say the items to be changed, or they can cancel the old clearance and issue a new one from scratch. Which they choose depends on how much is changing and why.

An instruction may authorize a (usually brief) deviation from a clearance, e.g. to avoid traffic or weather. ATC can give instructions to VFR flights without a clearance to amend, though, and this doesn't create a new clearance, so they're something different.


Did the X-15 ever conduct a point-to-point flight? The North American X-15 rocketplane flew at up to Mach 7 and at very high altitudes, it was also capable of spaceflight but these were quite steep parabolic patterns. At Mach 7 it flew leveled and my question is whether the X-15 ever landed on another airport than the one it launched from (attached to its B-52 carrier plane so actually the airport where the B-52 launched from). Wikipedia seems to be silent on this.

my question is whether the X-15 ever landed on another airport than the one it launched from

That depends on what you mean by "landed", "airport", and "another".
On its free flights, it never landed on another airport than the one it started from. However, it also never landed at the airport it started from. In fact, it didn't land at an airport at all.
It always landed on a dry lakebed near the airport. Whether you consider them part of the airport or not, is a matter of definition. As is the question whether you consider a dry lakebed an airport. I believe that the lakebeds were prepared with temporary runway markings, and they also may have cleared the "runway" from rocks and debris.
However, on aborted flights or captive carry flights, when it was never released from the carrier aircraft, it obviously landed attached to the carrier aircraft back at Edwards AFB.


What is a circling approach? What is a circling approach and why is it necessary? I know that if a runway is not suitable for an instrument approach, the pilots should execute landing on a runway which has an instrument approach available.

To add to the above points...
Circling Approaches are used when the Approach you want to use and the runway you want to use are not aligned with each other. Say for instance, you are arriving to the terminal area from the North. The runway you want to use is from the South (probably due to wind). You want to get down to the ground ASAP. You can get cleared to approach the airport using an IAP with a Southbound Final Approach Course. They will also clear you to circle the field in a certain direction. We will use East in this example. You will then get clearance to land on the Northbound (from the south) runway. A play by play would be to:

Follow the full procedure for the IAP with the 180° Final Approach Course.
Once you reach your Circling Minimums, maintain you’re altitude, and turn 30° to 60° to your left.
Turn back to your 180° heading in time to stay no more than 1.3 miles away from the runway surface for Category A aircraft (unless the airport has published alternate circling distances). It would be similar to a (right in this case) downwind leg
Parallel the runway to a point where you can make a normal downwind to base turn.
Start your descent to landing
Land on runway 36

If you never get the runway environment in sight, go missed at the original MAP.
If you lose sight of the runway environment at any time during your circling maneuver, immediately circle back over the runway to fly above it on your missed approach course. And go missed. Remember, the safest place in the airport environment is directly above the center of the runway.

One thing to be aware of on Circling Approaches is that the Circling Minimums are typically below Traffic Pattern Altitude. You will be flying slower and closer to the ground in the airport environment than you are used to. Caution must be exercised.

Also, the Circling Approach does not have to be a complete 180° turn around to land. It could be in any direction.

Finally, some approaches only have Circling as an option. This is due to the approach itself not being aligned with the runway. In the example below, the runway is aligned 179° and 359° magnetic.


Why does the B-29 not have pilot-accessible thrust? Watching this incredible B-29 Superfortress flight, I was amazed to see that it required a dedicated person to manage the 4 engines and their power levels.

Why was the throttle not placed between the two pilots, like the modern airliners of today?

This setup was actually pretty common for four-engine aircraft of the day.  Look at the cockpits of airliners from DC-4 to Lockheed Constellation, and you'll always see a dedicated flight engineer station -- not to the level of managing throttles (which would require a voice command from the PIC to change power setting, impractical for the reaction times required in flight), but to manage the relatively complex and failure-prone large radial engines.  The flight engineer station persisted well into the jet era -- at least to the early versions of the 747, which first flew in 1969.

However, if you look closely at a B-29 cockpit, you'll see each pilot has an individual throttle lever set -- they're not between the yokes because of the crawlway for the bombardier station.  Rather, they're outboard of the seats, near the (presumably pitch) trim wheels.  There were also propeller controls, though they're harder to identify in a cockpit photo.  With constant speed propellers, the only control required on an immediate basis was throttle (the flight engineer managed synchronization), and both control seats had throttles, as well as the ability to feather a dead engine.


Why is the Inertial Reference System not used to determine true altitude? Given three very accurate laser gyros and accelerometers I believe the Inertial Reference System (IRS) should be as accurate in determining true altitude as it is in determining lat/long, providing the aerodrome elevation was supplied at initialization.

I realize that pressure and density altitude are what is used in aviation, but could the IRS be used as a backup? Could it replace or backup a radar altimeter for approach/landing?

IRS will drift over time. Decision altitude is 200ft for ILS CAT I approach.  0.5nm drift is not to much for navigation but it will be huge difference in altitude and you can hit obstacles if your altitude has drifted just couple of feet. Probably it could be used if backed by GPS as EGPWS does or non baro RNAV approaches do. But even GPS precision alone is not enough in this case and you need WAAS.
Radio altimeter can give much better precision.


Why does the Cessna 208 Amphibian have extra tail surfaces? Mark Harkin, CC BY 2.0, via Wikimedia Commons

I've seen extra tail surfaces that look like additional vertical stabilizers on the C208 Amphibian. Why is there a need for this? I can't imagine that the floats reduce vertical stab effectiveness.

Well, it's the same reason that the Challenger ultralight demonstrates extreme "adverse yaw" in response to aileron inputs when flown with the doors on, but less so when flow with the doors off.  The floats-- like the doors-- increase the surface area in front of the CG, which has an effect similar to decreasing the size of the vertical fin (which, naturally, is behind the CG.)  "Directional" stability is decreased.
Just like if you took a weathervane and added enough surface area in front of the pivot point, it would stop working.
It's not uncommon for aircraft on floats to have modifications to increase the effective area of the vertical fin, usually by adding a small ventral fin below the fuselage.
Which begs the question-- Why did the Wright brothers take steps to increase the amount of vertical surface area forward of the CG on some of their aircraft?


How does aircraft maintain precise speed, e.g. in formation flying or refueling? I understand ailerons, elevators and rudders can be controlled to a very fine degree, and in precise flight, like formation flying, they can be used for very fine course adjustments to maintain the relative distance from another wingman.

But the throttle lever can regulate the thrust in range from near zero to several hundred kilonewtons by pushing it maybe 15cm forward. There's very little fine control to it and especially jet engines are sluggish to react to the changes.

How do pilots precisely fine-tune relative speed when traveling at high airspeed then? Are they using other tools - flaps, airbrakes maybe? Or am I underestimating the precision of the throttle, or missing some other mechanisms?

The key in holding the same speed as your wingman or the other aircraft is not to find the "perfect" throttle position, the key is to slightly adjust the throttle.

When you look at cockpit-videos of those formation pilots (like this - move the camera to the throttle, it's a 360-degree video), you can see that they are constantly moving the throttle. They almost never stick the throttle at one position. In that way, they can slightly adjust the speed and stay in formation with the wingman for a long time.

While flying in close formation at high speed, it's the same. Little adjustments of the throttle helps the pilot to keep the same speed as the wingman-aircraft. Flaps are not used in high-speed-flying because they can only operate below a maximum speed, otherwise they could get damaged. By using the air-brake, the handling of the aircraft changes, therefore the air-brake is not used very often while flying in formation.

tl;dr:

Skill


Can airflow reverse over the flight surfaces of a uav in high wind conditions Can airflow reverse over the wing of a uav in high tail winds and low forward airspeed i.e 25knt fwd airspeed in a 35 knt tailwind? What would be the overall effect on the elevator and rudder? I suspect the rudder would be remain the same but operate at a reduced efficiency however, wouldn't the function of the elevator reverse and/or become ineffective, especially at high angles of attack? As a point of note, this uav does not have ailerons, I believe the roll effect is achieved as a combination of pitch and yaw.

It is possible, but only if there were a very sudden and dramatic change that the aircraft was unable to overcome.  However, it would be only temporary.

If the airflow direction was actually reversed the control surfaces would likely be blown to a full deflection position one way or the other depending on which side of neutral they were.

Otherwise, the aircraft would still move forward at 25kts relative to the moving airmass, with the additive effect of the wind giving it 60kts of ground speed.


Does the cyclic in a helicopter re-center automatically? Just wondering if the cyclic in a real helicopter re-centers like a joystick for a computer?

I'm pretty sure the controls in a fixed wing re-centers due to natural physics if the plane is in dynamically stable flight, without the detent (extra force required to overcome fine-grained controls at the center).

Do the controls in a helicopter re-center in the same way? Not sure because I consider helicopters to be fundamentally unstable. I'm also curious about the center detent (if there is one) in a helicopter.

Helicopters (I have flown so far) does not have such detent positions for their controls just because, as you have said, the instability and the effects of controls on other controls. To reduce the workload some helicopters have systems which probably changes from type to type. While AB-206 helicopters does not have a system for cyclic centering or holding its position, UH-1 helicopters have force-trim system to hold the cyclic where you have centered or left.
AS-532 Cougar ( Eurocopter or Airbus Helicopters now. ) helicopter's cyclic has a cyclic-trim system which returns the cyclic to the position where the pilot set by pushing trim-release button on cyclic.
This is all I can tell for now. Not a complete answer for your question but I hope this helps.


How significant is the static buildup on the blades of the main rotor? And some questions related to this 1) Usually, a static charge is built on the helicopter when it flies through the air. If a person touches the helicopter before it touches the ground can that person get electrocuted because of the potential difference? 2) How significant is the static buildup on the blades of the main rotor? Are they grounded to the airframe of the helicopter? 3) What happens if a person jumps right into the helicopter while it's hovering, without completing the circuit with the ground? Like in the Matrix (1999), when Morpheus jumps off a building into a helicopter?

1) Technically, yes, it's possible to be electrocuted by a static discharge. The chance of it happening is so vanishingly small, though, that it's not generally a concern. A helicopter simply doesn't have the capacity to store enough electrical energy to be a direct danger. The real threat from static electricity is that it can potentially ignite a fuel spill, or something of that nature.

2) Depends on how you define "grounded". The linkages are coated with grease, which typically has a pretty high resistance. This means that low voltage (where "low" in this case can be up to 500 volts) across the junction probably isn't going to generate a meaningful current. However, static charges routinely exceed 10,000 volts, which isn't going to be affected by a thin layer of grease. So, you can generally consider the whole plane to be at the same potential.

3) Same thing that happens if you're on the ground and touch it. When you touch metal, you'll get a spark, yank your hand back, probably shake it a few times if the spark was particularly bad, and resolve not to do that again.


What is the piece that covers the top part of tires? I would like to know the name and the usefulness of this piece that covers the top of the tire of some planes, such as some Cessnas.

Those are called speed fairings.

They make the shape over the tire more aerodynamic and reduce drag, thus increasing airspeed and fuel efficiency.

This is a page in a Cessna 172R information manual that comments on the differences in performance when they are installed.


What is the procedure to turn a certified aircraft into an experimental aircraft? Last year at EAA Airventure I saw a helicopter (can't remember the model, but it was something like a Eurocopter EC135 or similar with a full glass cockpit). It was US registered (N-Number tail) but had "Experimental" written on the door.

When I asked the person at the booth why it was experimental they said it was because they used it as a test platform for new avionics packages, which got me thinking...

Is there a method to transition an aircraft from certified to experimental? Or is this done on a case-by-case basis through the FAA?

I can see advantages for an aircraft owner to want to transition to experimental if they want to keep up on latest (cheapest) non-TSO'd avionics and be able to do more work on the aircraft without an A&P. The downside is obviously higher insurance rates, but I'm not sure it would be a significant difference...

You essentially convert it to Experimental Exhibition, not Experimental Amateur-Built. That means more restrictions, depending on the FSDO. For instance, your operating limitations may prohibit passengers, or require permission for every flight over a given distance.

It is said that the FAA can be sensitive to people trying to put type-certificated aircraft into Experimental category for recreational use. Important advice below is that you should get permission from the FSDO before starting work on the airplane.

Even if you do this (and they likely won't like you converting say a Cherokee or a Cessna 172 to experimental), they will place certain restrictions on use, such as only flying within a 25 mile radius, and every year you may have to submit a "Program Letter" with a list of all the fly-ins and shows you are going to go to (since it is experimental-exhibition category, so you need to exhibit it!)

All that is to say, you probably will have a hard time converting a certificated plane to experimental and using it like it seems you intend to from your question.

Here is the relevant section from FAA Order 8130.2H.

  Section 10. Certification and Operation of Aircraft Under the
  Experimental Purpose of Exhibition or Air Racing

  General. Under the provisions of § 21.191(d), exhibition aircraft are defined as aircraft that exhibit the aircraft’s flight
  capabilities, performance, or unusual characteristics at air shows,
  fly-ins, and aviation events; for motion picture, television, and
  similar productions; and for the maintenance of exhibition flight
  proficiency, including (for persons exhibiting aircraft) flying to and
  from such events and productions. Under the provisions of § 21.191(e),
  air racing aircraft are defined as aircraft that participate in air
  races, including (for such participants) practicing for such air races
  and flying to and from racing events.

  a. Exhibition. A certificate for
  experimental exhibition must only be issued when an aircraft is to be
  used for valid exhibition purposes. Included in those purposes are
  organized air shows, organized fly-in activities, organized
  exhibitions, youth education events, organized aerobatic competition,
  fly-ins or meets, and movie or television productions. The duration of
  an airworthiness certificate for exhibition may be unlimited.

Here is an example of how to do it I found on a old page from the Robinson V8 Seabee Company website. (I found the page in the internet cache, so it is likely this method isn't foolproof)

STEP 1

Submit bill of sale for project Aircraft as "bought for salvage Parts" to the FAA. Add a separate letter of salvage in order to remove it from the FAA registry as Salvaged. This de-registers this A/C and is an important first step.

STEP 2

Obtain written permission from your local FAA Flight Standards District Office (FSDO) inspector in order to remove the data tag from the salvaged project aircraft. This step represents a great opportunity to develop a positive relationship with the FSDO inspector with whom you'll be working to complete the process. Be straightforward and explain that you require his help in order to certify your project in accordance with 14 CFR § 21.193, under a Special Airworthiness Certificate for the purposes of operating an aircraft in the experimental exhibition group 2 - Piston Engine Aircraft category, for the purposes of:

  Demonstrating flight proficiency; Demonstrating the superior engine
  reliability of modern V8 engines; and  Participating in exhibition of
  the aircraft at airshows and public event in order to educate the
  public about the unique and interesting characteristics of this
  aircraft

It is important to understand that the FAA FSDO inspectors are busy folks, and that they will appreciate the fact that you've done your homework. Maintain professionalism and don't expect an answer on the spot, as these inspectors have a number of strict procedures and guidelines within which they must work to accomplish the goal of certifying your aircraft. They deal with a great variety of aircraft and requests and may require some time to get up to speed on your specific request and understand the nature of your Robinson V8 aircraft.

STEP 3

Reserve a new N number on the FAA web site.

When your new N-number is confirmed  by the FAA, simply submit forms 8050-88 and 8050-1 for the new N number as:

  Manufacturer (preferably your new LLC Company or yourself). It cannot
  be the old manufacturer of the salvaged parts. Model  (Example:
  Military Seabee OA-15) or whatever you want to call it.  It cannot be
  the old model of the salvaged parts.

These forms need to be sent to the FAA Oklahoma City Registration Branch.

When your project is completed and ready for airworthiness inspection and operating limitations, issue a program letter to your FSDO inspector.  With FAA application for airworthiness form 8130.6.  They will take it from there.

Here is an example of program letter:

  Program Letter Nxxxx

  Date:  May xx, 20xx

  To:  Mr. FAA Inspector

  Federal Aviation Administration

  XXXXX Flight Standards District Office

  1234 Maple Lane

  anytown, state zipcode

  In accordance with 14 CFR § 21.193,  I request a Special Airworthiness
  Certificate for my aircraft Nxxxx for the purpose of operating an
  experimental exhibition, group 2 -  Piston Engine Aircraft. 1) For
  purposes of demonstrating flight proficency.  2) To demonstrate the
  superior engine reliability of modern V8 Engines.  3) To participate
  in exhibition of the aircraft at airshows and public events to educate
  the public about the unique and interesting characteristics of this
  aircraft.

  The aircraft description is as follows:

  Manufacturer: Your LLC                                    Registration
  No.:    Nxxxx

  Model:  Your model
  Serial No.:    xxxxx       Engine Make/Model: Robinson  LSV
  No. of Engines:    01 Propeller Make/Model:    xxxxx

  Number of Seats: Four

  The aircraft will be available for inspection at it’s base airport:
  (your airport and hangar location).

  The aircraft will be weighed prior to flight to determine weight and
  balance data. The marking requirements of Part 45 will be complied
  with prior to flight, including permanent attachment of a fireproof
  identification (data) plate, permanent application of appropriate
  registration marks.

  The following placards will be displayed in the cockpit in full view
  of all occupants:

  The word “EXPERIMENTAL" displayed near the entrance to the cabin or
  cockpit; minimum 2 inches, maximum 6 inches in height.

  "Passenger Warning – This Aircraft Does Not Comply With Federal Safety
  Regulations For Standard Aircraft" .

  Instruments and system controls will be adequately marked, identified,
  and function properly prior to flight.

  The power plant /propeller will be ground-run to sufficiently
  determine they are operating properly for flight.

  The Aircraft will be maintained under an Annual condition inspection
  that meets the scope and detail of 14CFR part 43, Appendix D.

  I request that airworthiness certification operating limitations be
  issued permitting me to operate the aircraft in phase one within 50
  Nautical mile radius of (Your Base Airport) with the exception of all
  A,B,C and restricted airspace and avoiding flight over populated
  areas.  Ten hours of  phase one flight tests will  be conducted to
  demonstrate control ability, engine reliability and establish the
  flight envelope.   After Phase 1 flight test completion,  I plan to
  operate the aircraft under Phase two operating limitations under
  VFR/day and VFR/night conditions under a group 2 Experimental
  Exhibition airworthiness certification within the continental U.S.
  proficiency area.

  Kind Regards,

  You


What is acceptable visual cue at Decision Height when performing CAT II approach? For CAT II approach, the decision height is below 200ft but not lower than 100ft with RVR of 300m. In this case, if the aircraft is at 100ft above the ground, should the captain of that aircraft be able to see the runway threshold lights (green) at that moment? Or seeing the approach lights is considered sufficient to continue?

Short answer: for CAT II, seeing the approach lights (minimum 3 segments) is sufficient given a lateral element is also acquired.

Visual acquisition definition may vary between FAA, EASA, ICAO, etc. What follows is for EASA (as tagged).

For CAT II, you may descend below the DH if you can see:

3 consecutive approach lights,
or touchdown zone (TDZ) lights,
or runway centerline lights,
or runway edge lights,
or a combination of the above,
and must include a lateral element, i.e., crossbar, threshold, or TDZ pattern lights.

(Source: Airbus) A crossbar plus 3 segments.

For CAT IIIa and CAT IIIb (fail-passive; no roll-out mode):

The same as above, minus the lateral element.

For CAT IIIb (fail operational; roll-out mode):

At least one centerline light is attained and can be maintained.

Do not use for flight.


Why don't fighter jets take off vertically? I've heard the claim repeated many times that some modern fighter jets have an installed thrust greater than their weight, so theoretically they could accelerate straight up.

I've never actually heard of this being done, however. It sounds useful, though, especially on the deck of an aircraft carrier. Imagine: we could take out the whole catapult system, and replace it with some sort of a system to pick up an aircraft and turn it vertical.

Why is this not done?

They can climb vertically, but this works best if they are several tons below their maximum take-off mass. Fighter jet engines need a lot of fuel, and at the beginning of the flight the aircraft will be too heavy for vertical climb. Also, the landing gear would need to be rearranged if the plane is to take off from any airport.

Even a thrust/weight ratio slightly above 1 at maximum take-off mass will not be enough, because the aircraft needs some airspeed for its control surfaces to become effective. If no thrust vectoring is installed, the aircraft will be uncontrollable in its initial ascent. The Harrier VTOL jet uses bleed air which is ducted to nozzles at the extreme ends of fuselage and wing for low-speed attitude control.

It is conceivable that the fighter will hang vertically on a wall, with its wheels locked in clutches which will release it when the needed thrust is reached. With thrust vector control the aircraft could be controlled over the full trajectory until it transits to horizontal flight, and could even land vertically. But this would need specially prepared airfields and use much more fuel than a conventional take-off, leaving less fuel for the mission.


What happens to #2 if a formation flight violates a FAR? In a formation, it's generally accepted that the lead pilot is responsible for safety of flight and navigation.  #2 is, colloquially, responsible for not hitting lead.  That is to say, in close formation, you never take your eyes off lead.  In many situations, #2 may not even be in radio communication with lead or monitoring ATC frequencies and his overall situational awareness will be degraded.

If lead, who is responsible for navigation, takes the flight into protected airspace (i.e, flies into Class C airspace without first establishing two-way radio communication) would both pilots be violated, or just lead?

For clarification:

The regulations governing formation flight are pretty sparse.  FAR 91.111, 91.146 and 91.153 are the only mentions of formation flying in the regulations.  There is no requirement for communication during the flight - 91.111 just requires that all pilots agree to operate in formation.  It is not unusual in a formation flight for lead to be on one frequency (talking to approach), and the wing to be monitoring another (or not monitoring at all).  Most communication is done via hand signals.  I do know that ATC treats formation flights differently - they effectively treat it as one aircraft (ATC Manual 2−1−13).  If the flight is cleared to land, both aircraft a cleared to land - #2 does not need to acknowledge.  Hence the question who is responsible if the flight (a single aircraft in the eyes of ATC), violates an FAR?

In the eyes of the FAA, the wingmen are individually responsible if they violate an FAR, even if they are led into it by lead.

The controlling NTSB decision is:

3 N.T.S.B. 3302, NTSB ORDER NO. EA-1560, 1981 WL 40208
Administrator
v.
MERRELL R. GOSSMAN, EDWARD J. MODES, AND HOWARD MORGAN, JR., RESPONDENTS
Docket No. SE-4591, SE-4592, SE-4593
Adopted February 13, 1981

  As the law judge stressed, each pilot-in-command of an aircraft “is
  directly responsible for, and is the final authority as to, the
  operation of that aircraft” and each pilot has the affirmative duty
  to comply with the minimum altitudes prescribed by section 91.79,
  which contains no exception for aircraft in formation following a
  leader.


Why is the input power of an ADS-B Transponder much lower than its rated transmission output power? ADS-B Transponders are usually rated with 150W or 250W transmission power, however the electrical input at 14V is rated much lower, usually around 6 Watt. How can that be?
150 W transmission power with an efficiency of 70% would result in > 200 W input ~ 15 Ampere at 14V. Even if its not CW, there would still be a significant current peak.

The rated TX power is the maximum power emitted while transmitting. The electrical input power is much lower, because the design of the transponder is such that it accumulates energy from the input at relative lower power, to burst that out in one go on the output at high power.
The transmission of a ADS-B extended squitter has a duration of 120 microseconds. Since the modulation is pulse-position modulation, the transmitter actually only transmits for 58 microseconds per message. If the TX power is 250W, a single ADS-B message costs about 0.015 J (assuming 100% efficiency). The maximum squitter rate for ADS-B is 6.2 messages per second, equating to an average of approximately 0.1 Watt of transmitted energy. Other systems hosted by the transponder (Mode S and TCAS) are able to produce easily ten times more messages each. Mode A/C uses much fewer pulses but can have very high reply rates. This brings the average total transmitted power to over 2 W for congested airspace.
Internally in the transponder you will find big capacitor(s) that get charged by the aircraft's electical system, and discharged by the transmitter. They act as a buffer, preventing peak power surges in the aircraft system.


What size/engine/payload aircraft would be needed for carrying two passengers and a motorcycle? I'm not even in the realm of knowledge of aircraft so don't chew me out on lack of terminology please.

My objective is to fly myself and a 300-pound motorcycle to destinations to ride from there.

I weigh 185 lbs, the motorcycle weighs 300-400 lbs, any secondary seating and other interior furnishings would most likely be removed to reduce weight, and, obviously, all the necessary components would stay. As a side note, the aircraft needs sufficient enough door to get a small motorcycle in. Let's not even talk about how unsafe this might be; this is all hypothetical.

How large, or what class, of an aircraft would be needed for such a task to be completed?

The question is incomplete without information about the range this aircraft should have. Pilatus in Switzerland is always fond to tell of one of their customers who bought not one, but three PC-12s for exactly this purpose, and has one plus a Harley-Davison motorcycle stationed on each continent of interest. The size of a PC-12 allows the installation of a crane, so loading and unloading of the motorcycle are simplified.

PC-12 side view, with open cargo door (picture source)

Obviously, even a PC-12 does not have the intercontinental range to go anywhere, but if you plan to stay within one continent, range is not an issue. Alternatives in this class are the Czech Aero 270 or the Cessna 208 Caravan. All use a PT-6 turboprop engine, and you will need professional maintenance to keep them flying, so using them does not come cheap.

A more reasonable alternative would be piston-engined, and here the Cessna 206 or 207 (which @Terry already suggested) would be a candidate. However, fitting the bike in will be a challenge.

If you want more internal space and are not afraid of antique taildragger airplanes, the Antonov An-2 or the Canadian DHC-3 Otter would also be a good and reasonably priced choice - however, maintaining one (and especially its radial engine) will also burn a hole in your pocket.

DHC-3 in Pensacola (picture source)


What's the difference between overrun and overshoot landings? Is there a difference between overrun and overshoot landings or are they exactly the same, talking about a runway excursion?

They are more or less the same and are often used interchangeably. FAA AC 91-79 Runway Overrun Prevention defines runway overrun as:

  A runway overrun event is a departure of the aircraft from the end of the intended landing runway surface.

It means that the aircraft has touched down on the runway before going off it. Overshoot is used in the same sense (note that overrun/overshoot occurs both in TO/landing).

However, there is one case where they are used differently. Overshooting the runway also can mean that the aircraft has touched beyond the end of the runway i.e. missed the runway entirely.


Flying Considerations during an Eclipse? August 21, 2017 will see a total eclipse of the sun across large sections of the United States, generally between about 10a.m. and 2p.m. (depending on location and timezone)

If one is flying during the eclipse, are there considerations, other than sudden transitions to darkness and then to light, that should be taken into account?

Do Pilots flying during this time need to be Night Current?
Can time logged during the eclipse be logged as Night Conditions?

Do Pilots flying during this time need to be Night Current?

No, that time does not fall within what the FAA considers "night"

The FAA defines night currency in FAA FAR 61.57

  FAA FAR 61.57

  (b) Night takeoff and landing experience. (1) Except as provided in
  paragraph (e) of this section, no person may act as pilot in command
  of an aircraft carrying passengers during the period beginning 1
  hour after sunset and ending 1 hour before sunrise, unless within
  the preceding 90 days that person has made at least three takeoffs and
  three landings to a full stop during the period beginning 1 hour after
  sunset and ending 1 hour before sunrise, and—

  Can time logged during the eclipse be logged as Night Conditions?

Nope, same reason as above it does not fall in what the FAA considers "night".


How does the pilot check if an engine fire is real? I've read this question and its answers basically asking why putting out an engine fire is not left to the computer but a manual task.

One of the points mentioned is that there simply might be a sensor error or similar and the engine isn't actually on fire, in which case you obviously don't want the computer to needlessly shut down an engine.

My question however is, how do the pilots assess wether the engine is actually on fire or not?

All planes I've been on had their engines very close to the aircraft and I doubt they are easily if at all visible from the flight deck. I would assume a good indicator might be the loss of thrust, but that could also be detectable by a computer. Do the pilots have cameras they can activate to check on the engines, or do they call the cabin personal and ask them to take a peek, do they walk out and check or is it based on how loud the passengers scream in the back? I guess all of these work, but what is the common procedure?

Engine fire implies that there is a strong heat source (commonly a fire, but could be a hot substance) in a location there should not be, usually around the outside of the engine.

Engine fires do not necessarily need to be connected with a loss of thrust.
Visually, they are pretty diverse- there may be smoke, there may be little smoke (aside from that, what would you do at night?).

The general rule is to treat the cockpit instrument indications as real every time. You do not need a visual confirmation.

You would rather take safe action a thousands times too many than one time too little. The aircraft is designed to fly on one engine and it's probably one of the most common exercises for pilots in simulators.

You are correct that sensors do get it wrong. Here is a very recent incident that involved just that. The reason for the sensor discussion is that a decision is only as good as the information you can base it on, and a human is generally a better decision maker than a computer as it currently stands. Take this very complicated and confusing situation for instance- how would a computer decide and respond?

There is no physical damage in hitting the fire button which will shut the engine down. Discharging the Halon fire agents would normally require a new bottle. It is a bit of a 'hard' engine shutdown: it cuts fuel, bleed air, electricity and hydraulics. If the fire warning (i.e. heat source) persists, you generally escalate it to discharging fire agents, although in most cases shutting the engine off is a sufficient measure.


Why would a helicopter climb in a spiral? I was just watching the James May's Toy Stories Christmas Special Flight Club*, and in it he commented that the helicopter was making a spiral climb to 8,000'.  Why would the pilot spiral, not just essentially go straight up?

* An excellent series if you're a big kid who enjoys toys, and as a bunch o' GA pilots, I'd think that covers most of you!

A helicopter will achieve its best climb rate at a moderate forward speed. Climbing in a spiral helps to have forward speed in what is essentially a vertical climb.

In a hover all the airflow which is available for lift creation must be generated by the rotation of the main rotor. This means that a small amount of air must be accelerated by a lot. If the helicopter adds forward speed, it can achieve a higher mass flow through the rotor, and now less acceleration is needed to achieve the same lift. This improves the efficiency of lift creation. If the helicopter goes faster than its speed for maximum rate of climb, aerodynamic drag grows too high and reduces efficiency again.

The difference can be dramatic: Below is a plot of the speed versus altitude of a generic helicopter and turboprop plane in comparison to the V-22 tilt rotor. Remember that the available power is roughly proportional to air density, and you can start to see how much more power is available for climbing when the helicopter flies with a moderate forward speed.

Flight envelopes of a generic helicopter, a turboprop plane and the V-22 tiltrotor (picture source). Thanks to @mins for inspiring me to expand the answer a little.


Flying out from an uncontrolled field, should I contact approach or departure at the nearby control field? I am a new pilot who flies out of an uncontrolled field. When I depart and want to ask the controller for the nearby controlled airfield for flight following, should I contact approach or departure, or it does not matter?

Approach and departure are two facets of the same facility, the TRACON, and it doesn't matter which you call, unless you're an IFR aircraft on an active flight plan or you have a flight plan on file that you want to activate.

For flight following, more important than picking between approach and departure frequencies, is to contact the TRACON on the frequency for the airspace that overlies your position.

For example, at Hollister, the TRACON is called "Norcal," and it handles dozens of different sectors, each with its own frequency.

The frequency for approach and departure at Hollister are identical because that frequency is the arrivals frequency for San Jose International Airport (SJC). That's because Hollister is underneath the approach path for SJC, and that's whose radar screen you will pop up on.

What you should do is look up the frequency for your airport (or for a nearby airport) in the A/FD, in Airnav.com, or in your GPS database, and use that. If it has a discrete departure frequency, then you should probably use that, even though its for IFR departures, but for VFR, it doesn't really matter.


How are timed flybys executed, and what are their accuracy? Thought experiment: Suppose I am equipped with an ideal automobile which can reach speeds of 700mph.  On a highway, I can deftly maneuver around light traffic to achieve an average speed of 500mph.  A friend, standing on an overpass, dares me to pass under him at high speed at a precise moment in time some distance in the future giving me enough time to reach my destination (if perhaps a bit early or late).

I would find this maddenly difficult.  Likewise, aren't timed flybys difficult?  How are they executed?  Given an F16 with an average pilot, how accurate could a stadium flyby be timed?  What technology is used?

Edit:  Let be more specific.  I.  What are the exact procedures used by a flight team performing a timed stadium flyby.  II.  Given a highly trained team, what is the expected deviation from desired flyover team and actual flyover time?

I still don't think this question has been answered in detail.  Also, there must be some technique that dates from the pre-GPS era.  Even with GPS, I suspect (but I may be wrong) that the answer is more than staring at a GPS and intuiting the appropriate adjustment in speed.

The way they coordinate them is actually extremely simple.  The show at a ball game (or any major event) is usually very heavily choreographed, so they know exactly when it's going to end (seriously, often down to the exact second.  They practice the heck out of those things.)  So, step number one, the organizers tell the Military the exact time for the flyover in the show.

For the militaries part, well, it's important to remember that military aviation involves a lot of instances where you have to be over a target, dropping a munition, at an extremely precise time (again, down to the second).  Otherwise you may screw up the timing of the whole operation, or the target may be gone, or the defenses may be up (etc etc).  It's really important to be precise in the military.

The procedure itself is still fairly conventional though.  You figure out what time you need to be there, then you figure out how much time it will take you to get there.  Subtract the latter from the former and boom, you have the time you need to take off.  Then all they need is a few check points to make sure they are on schedule, approaching at the proper speed.  And they adjust as needs be.

Basically, keep an eye on the clock, slow down if you're ahead of schedule, speed up if you're behind.  To increase accuracy, you may build in a holding spot near the event, that way if you're 20 minutes early (of if the planning goes out the window for the show and they're late...), you can hold there and pick the approach up again when the time is right.  It's still all about watching the speed and the clock though.  With a lot of practice, you end up hitting your waypoints, hold points and destination, with (literal) military precision.

If you want to know more details though, check out this article from ESPN: How Flyovers Hit Their Exact Marks at Games.

As a final thought, I think you may need to adjust your thought experiment.  Military aircraft can get clearance through just about any airspace prior to the actual mission.  Plus, they can approach from any direction, so it's pretty easy to find a lane that has no traffic.  So in your car thought experiment, there should have been no traffic and a straight shot to the overpass.

Plus, there should have been regular beacons (like GPS or NDB fixes) to tell you how far you are from that overpass.  And the person driving the car would have known exactly what time they needed to pass each beacon in order to get to the overpass in time.  Then, with a heck of a lot of practice, I'm sure that driver could go under that underpass at the exact right moment pretty much every single time...


What documented practices are there for NOTAM creators and handlers to combat NOTAM spam? Sadly, NOTAM spam is a persistent thorn in the world aviation community's side.  Bureaucratic rump-covering exercises lead to NOTAMs being issued and distributed that are mere noise to the average airman, leaving them pawing through pages and pages of briefing packets looking for a needle in a haystack.

As airmen, we're largely stuck with the results of this all.  While better filtering would indeed be an improvement over what we have now, it would but paper over the underlying problem: the fact that there's this sea of noise to begin with.

How can NOTAM creators and handlers can this spam problem?  Are there documented practices or guidelines they can follow to reduce the amount of rubbish that gets input into AFTN and dutifully delivered to hapless airmen everywhere?

It's a real problem. Probably the worst you could do is read a raw DUATS briefing. If your EFB includes briefing support, those will do a slightly better job formatting and organizing everything. If you're flying VFR most of the time like me, keywords like IAP, ODP & SID following an airport identifier are only relevant to IFR, and not information concerning that flight.

Needless to say, the burden is on the airman right now. Maybe if someone passed these abuse cases to a forward-thinking FSDO, they might have a chance of some relief.


Would it be more effective to increase the length or chord of a rotor blade for better performance? Would it be more effective to increase the length or chord of a helicopter rotor blade for better performance? (Say, 10%?)

It's not so easy. The blade length, chord and engine power are connected in complex ways, and for each desired performance there is an optimal combination of those parameters.

Rotors (and wings) generate lift by accelerating air downwards. The lift is proportional to the rate of change of inertia of the air. This, however, also changes kinetic energy of the air and therefore requires power. This is called induced drag.

Since inertia is proportional to velocity, but kinetic energy is proportional to the square of velocity, it is more efficient to accelerate a larger amount of air to a lower speed.

The amount of air affected is proportional to the area of the rotor disk (the whole area in which the blades move) and that is simply ($\pi\times$) square of blade length. So in a sense the answer is easy: only blade length has effect, blade chord does not.

However, increasing the blade length also increases the form and skin drag of the blades, so beyond some point the form drag will exceed the induced drag and any additional increase in blade length won't improve efficiency further.

Even more importantly, a longer blade will be heavier and therefore will have to be stronger to withstand the centrifugal force when turning, and stiffer so it does not bend too much when not. But that will make it even heavier and you'll reach a point where you simply exceed the capabilities of the material. And of course higher weight also means more lift is required. These effects will further reduce the optimal length of the blades.

The blade chord is then a secondary parameter governed by two concerns: the chord has to be long enough so the blades can generate the necessary lift without stalling and they have to be strong enough, strength being proportional to chord times thickness.

So if you want to improve load, you can try to improve efficiency, which you could do by making the blades longer, but you need to find a material with higher specific strength, otherwise the increased weight will outweigh the improved aerodynamic efficiency.

If you don't have that, you will primarily have to increase power of the engines. The optimal blade length may then be longer too, but you will be hitting the limits of the material quickly; that's why there are multi-rotor helicopters.

If you instead meant speed, that's a completely different issue and neither blade length nor chord play a significant role there. In forward motion, the speed of a helicopter is limited by two constraints: sufficient portion of the retreating blade has to move aft relative to the airflow and the tip of advancing blade must not exceed speed of sound (actually, critical Mach number, which is somewhat lower). The first requirement means the tip speed must be around three times higher than the maximum forward speed, otherwise the retreating side of the rotor won't be able to generate enough lift and the aircraft will roll to that side. Together with the second parameter, it limits the speed to about a quarter of the critical Mach. There are some experimental twin rotor (intermeshing, side-by-side) helicopters that don't mind the lift asymmetry and can fly somewhat faster. But it has nothing to do with blade length; blades of larger rotor spin at lower rpm to maintain similar tip speed.


What is the object on the nose of this HondaJet in this marketing video? In the third Hondajet marketing video there is a sword-like object visible on the nose of the aircraft.

What is this used for?

It is a Pitot tube.

It is used to measure some air data values, depending on the model.

The most basic will measure only pressures (and then "derives" the velocity of the aircraft), the most advanced will measure angle of attack and sideslip as well.

The one in the photo is particularly long to make sure that is measuring values in the undisturbed airflow in front of the aircraft. It is a model usually seen in flight tests or on fighter aircraft.

In flight tests, because despite the accurate CFD modelling available today, uncertainties are still present during the first flights (that's why they are tests). The long probe gives a reference as much undisturbed as possible.

During normal operations you will generally find smaller probes, such as the ones found in this other question.

Fighter aircraft need the long boom for the reasons seen in this question.


Why could a Rotax 914 light aircraft lose power at 7000 feet? I was flying an RV 4 equipped with Rotax 914 engine and variable pitch propeller.
The problem was observed during flight above 7000 feet; vertical speed became 0, RPM overshoot for 2, 3 seconds to 6300 when the turbo engaged for gaining height. I did make an effort for turbo but was not gaining height. It felt like under power, but take off was normal. Air Box target pressure was normal. All other engine parameters  also normal. So I came back to pavilion.

Could you please suggest possible causes?


How do you set up your nav instruments and coms during ground operations and takeoff? I have an HSI, an OBS, and a GPS. I normally set my HSI to runway heading, my bug to the wind direction, and the GPS to destination airport/waypoint (which will give me my turn out heading). I don't normally move my OBS. Once I get in line to depart, I set my bug to my departure heading.

For my coms I put the tower frequency in COM1 and the ground and guard in COM2.

Is there a standard procedure for setting up your nav instruments and coms? Is there a better or more efficient method than what I am doing? I have been thinking I could set my OBS up for the approach and my second option in COM1 as CTAF or tower at the arrival airport. What does everyone think?

I think it is save to say that it is a good practice to do anything you can on the ground rather then doing it in the air.

My setup: I usually end up with a similar set up as you do, though I don't use GPS much, but prefer hopping from one VOR to the next ;) (Well, I'll have to add that I'm not the most experienced pilot around here, for sure!)

Basic principle: I try to follow the rule I mentioned up there: I try to decrease the workload in the air by doing it on the ground already. That's why we make our route up on the ground, not as we go (well, one of the many reasons).

Let's say I have Com1 and Com2, each with a standby frequency as well as two Nav's, also each with a standby frequency: Before taxi, I'd have Com1 Active set up as tower and be listening and talking to Com2 to clearance, having ground in the standby. As soon as I have my clearance, I can put in my initial heading with the heading bug (not flying SIDs), as well as the Dep. frequency in Com1 Standby. This way I have all ground related stuff in Com2, all air related stuff in Com1. As for the Navs and the OBS: If there is a VOR at the airport I'm gonna put it in Nav2 and turn the OBS to initial takeoff heading (mostly runway heading). This is just as a support, "heading" still means pointing your nose to where the controller says, no matter what track the wind makes you actually fly. But then I know where I'm at and can already figure out what the wind is doing on my climb out. Nav1 goes to my first VOR, and depending whether I go direct or join an airway, I center the needle or set the OBS to the airway track respectively. The standby frequencies of the Navs are set to my second waypoint on Nav1, and whatever I think I'll need afterwards on Nav2. After takeoff I use Nav1 primarily to navigate, and Nav2 to verify my position (such a aircraft would usually have DME, so that you don't need to cross bear your position with two VORs, but if there is time to do so, why not).
In the air I usually don't use  the standby freqs much on the Coms, and just swap Com1 and Com2 when changing frequency. Before landing, the same thing counts as before takeoff: Take as much workload off in advance. Thus I'm setting up the coms (I got 3 spare frequencies when talking to approach or center or whatever, the'll all be filled in with usefull frequencies like ATIS, Tower and Ground), the Nav's for the approach (with missed approach in standby if available).

Well that was quite a novel, I hope you didn't fall asleep halfway through. This is what I do, and I get along with it quite well. I am not saying it is the 100% perfect thing to do, and (as Simon points out in his answer) you should do whatever you feel the most comfortable with.

Summing up, I think doing as much as you can in advance is key in flying (especially IFR), as it gives you more time in case you need it for something else to do.


What backup systems are in place for flaps actuated by sliding block guides? Looking at this video of a 737's flap extension, it looks like there is just one screw per side driving all of the flaps. Are there any systems in place that will allow the flaps to extend in the event of the linkage failing? What if hydraulics are lost? Also see point 3 on this question for more information about the flap type I am asking about (but generalized answers are welcome).

Given the footage in that video (rotating shafts rotating a jackscrew) There are 2 main failure modes I can think of: the linkage to the jackscrew fails or the jackscrew itself fails.

If the linkage fails the flaps will just not work. Jackscrews will hold the position of the flaps making the flaps fail up (not extended). There should be a feedback mechanism to stop the operational set of flaps before the asymmetric flaps affect the flight.

The jackscrew itself is engineered to not fail if properly maintained. There are also multiple jackscrews per wing

When flaps fail up the plane can still land. It just needs a much longer runway to account for the higher landing speed and a brake inspection. For example in this incident a Boeing 737-800 landed (almost) normally.

When flaps won't retract after takeoff the crew will circle back to the airport and land again with the flaps in takeoff position. This is somewhere between flaps full up and flaps in normal landing configuration.


What are the dimensions of an approach plate plan view in nautical miles? I am writing some software to work with approach plates on a website, but I cannot find the scale of the plan view.

I am trying to convert the position of a plane in latitude and longitude onto the approach plate and keep it to scale.

If I knew how many miles wide each plate was or tall, I could make this happen.

Thank you for the help!

FYI, what you're trying to do is called "georeferencing."

The scale for each plate is whatever is required to fit in all the relevant information without wasting space. Therefore, to properly geo-reference each plate, you will need to identify at least two points (e.g. CUTIS and CFVGK in this case), look up their lat/long in the published tables, and calculate the scale from there.

Note that some charts (more commonly SIDs and STARs than IAPs) are explicitly marked "NOT TO SCALE", which means this tactic can't work at all. And even some charts that are mostly to scale may have a few elements that aren't, usually transition fixes or navaids, marked by a double zigzag.


Why do Airbus and Boeing have different approaches to bleed air systems? Reading Wikipedia and other questions like this, made me curious as to why Boeing uses bleedless architecture for its B787, while Airbus thinks differently for its A350 XWB (and Rolls-Royce thinks the same).

Both companies switched to composite materials for their new aircraft so they agree about some new technologies, but not all, since they have different approaches to the air systems.

Why did Airbus remain more conservative on this topic (even if its model is about 5-7 years younger than the B787)? What is Airbus's argument to sustain this choice and how does it compensate the disadvantages (cited by Boeing in linked post) of the traditional bleed air systems?

To be more precise, development of new technologies bring both companies to share many new common approaches because advantages are clearly evident, for example: glass cockpit, composite materials, wing extremities (sharklets/raked wingtip/winglets), bigger fans, but they are different ideas about others, such as control yoke, flight envelope, chevron onto engines and, effectively, bleed air.

I found information about "why" Airbus choices to avoid chevrons or prefer a side-stick joystick for example, but not about bleed air systems

Nobody can tell you for sure without insider knowledge, and insider knowledge would be confidential in this case, but ultimately it boils down to risk management. Every new development carries a risk of budget and deadline overruns and of problems surfacing in operation and the manufacturer needs to be reasonably certain they can put the product to market before they run out of money.

When Boeing started developing 787, the 777 was selling well, so they had the budget reserve to risk more innovation. And it did have some problems in operation with battery fires. Airbus was in worse position when developing A350, so they stuck to more tried technologies to keep the risk lower.


What are the differences between blue airports and green ones on the low en-route chart? As far as I know, a brown airport on the low en-route chart does not have an approach procedure but blue and green airports do. But what exactly are the differences between these colors?

From the FAA Aeronautical Chart User's Guide:

  Facilities in BLUE or GREEN have an approved Instrument Approach
  Procedure and/or RADAR MINIMA published in either the FAA Terminal
  Procedures Publication or the DoD FLIPs. Those in BLUE have an
  Instrument Approach Procedure and/or RADAR MINIMA published at least
  in the High Altitude DoD FLIPs. Facilities in BROWN do not have a
  published Instrument Procedure or RADAR MINIMA.

So the green ones are in the FAA TPP but not in the DoD High Altitude FLIPs.


ARINC429 - Encoding and Decoding of BINARY DATA In ARINC429 protocol, how to encode and decode FAN DISCHARGE STATIC PRESSURE (LABEL - 127).
Range is 1.5 to 30.0
No of Sig. Bits - 11
Resolution is 0.016
What should be the value to be loaded into the word if my pressure value is 1.5 PSIA ?
As per my calculation, value need to be loaded = 1.5/0.016 = 93.75 which is a fractional value that cannot be loaded. So the value need to be scaled by some value.
Total no of data bits = 19 (including sign bit)
No of bits for representing value = 18
No of Significant bits are 11
Value need to be shifted by (18-11) which is equal to 7 bits => Max value = 128. So scaling factor will be 127 now.
Value before scaling = 93.75
Value after scaling = (93.75 x 128) = 12,000
Value to be loaded (bits-28 to 11) = 00 0010 1110 1110 0000b
But at the decoding side, the value will be decoded as 00 0010 1110 1b (i.e., Only 11 bits of data will be considered for decoding, and rest of the bits will be padding bits).
Decoded value = 00 0010 1110 1b = 93
Decoded Pressure value in PSIA = 93 x 0.016 = 1.488.
Please let me know, encoding and decoding is correct or not ?
Is it OK to take approximate value instead of actual value after decoding ?
What is the use of padding bits. Lets say in this example, i am using only 11 bits for representing a value due to which fractional part is getting discarded. So can i use these padding bits to represent fractional value ? In that case, How the value gets decoded ?
Thanks in advance.

Going off of the resolution, it looks to me like the actual label range would be 0-32.0, which with 11 significant bits gives an LSB of $\frac{32}{2048} = \frac{1}{64} = 0.015625$.
$1.5 * 64 = 96$