7 ms·

I don't think the report deepens the mystery, it answers questions. The flight data recorder information was recovered and tells what happened. The flight speed

by bugsy 15y ago

I don't think the report deepens the mystery, it answers questions. The flight data recorder information was recovered and tells what happened. The flight speed sensors weren't working and so autopilot shut off while the captain was taking his rest period. Then the two copilots didn't know what to do and called him. When he came they all continued doing random things indicating none of the three had any flight training that they remembered. This behavior, of not knowing how to deal with flight problems because they are used to running everything on autopilot, is not uncommon in airlines based in third world countries where pilots are the nephews of autocrats, but is unusual for French pilots.

garyspringer 15y ago
So, are there no pilots in french airlines who also happen to be nephews of people in power?
rbanffy 15y ago
The question not answered is why three trained pilots made wrong guesses as to what was going wrong with the plane. BTW, I imagine a pitot tube placed on the body of the engine would not need extra heating and would be very unlikely to ice. You can even place it inside the exhaust and compensate the reading for engine flow. We have to figure out what went wrong, what mistakes the crew made in order to prevent future accidents like this. And I, coming from a third-world country, take offense at your statement. Pilots here endure very thorough training. One would have to be a lunatic to trust his nephew to a flying computer. The pilot must always know what's going on. And that brings the main point: people die when the machine surprises its operator. "Smart" planes have become so smart pilots have trouble understanding what they are doing under all that software. And that's assuming the software is not buggy and they didn't got a very unfortunate NullPointException in the worst possible moment.
- icegreentea 15y ago
  I would a pitot tube in exhaust work? There's very little 'normal' air in the exhaust, just the engine exhaust, and unless I got my physics completely wrong, will always give the same relative speed relative to the plane(pivot tube) at any given engine setting... which doesn't tell you anything about the actual airspeed (which is what you need). Pivot tubes are 'tubes' located away from the body of the airplane for the reason that they get away from the boundary airflow to give accurate airspeed readings. Attempting to 'compensate' for other factors just introduces more uncertainty, which is exactly what you don't want when you're 5 knots above stall.
  - borism 15y ago
    exactly! Let's imagine a plane starting take-off roll. Engines are spinning up to full throttle (99-100% of thrust), but airframe just started to accelerate slowly. Compensating for anything is pretty useless in this case - airflow trough the engines is even higher than during cruise, but airflow around wings is quite minimal.
  - rbanffy 15y ago
    Is the engine airflow at any given regime completely independent of airspeed? I would never use it as a primary source, but it could be used to flag abnormal readings of other instruments.
- borism 15y ago
  BTW, I imagine a pitot tube placed on the body of the engine would not need extra heating and would be very unlikely to ice. You can even place it inside the exhaust and compensate the reading for engine flow. There are such things in the engines! They're used to feed the data about engine performance to FADECs (http://en.wikipedia.org/wiki/FADEC http://en.wikipedia.org/wiki/FADEC) and the crew. But they're totally useless for airspeed calculation! Bear in mind that air flowing trough and around the engine has totally different dynamics than the air passing around the rest of the airframe. Well, that's kind of the point of the engine - to create thrust, isn't it? That's why airspeed, altitude and AoA sensors actually have to be placed further away from the engines - so that they give as accurate picture as possible.
  - rbanffy 15y ago
    Can't you compensate for that? Most of the time planes fly normally - data could be gathered on how to relate the readings of engine management sensors to airspeed. I don't mean using it as a primary source for airspeed data, but backups in case other sources show weird or no data. The data that comes from those sensors already enters the cockpit, so it would make sense to use it.
    - borism 15y ago
      You might be able to, but I imagine the calculations will be very complex and readings will be highly unreliable in anything but ideal conditions and constant speed level flight. But yes, I think the conclusion after AF447 investigation is completed will be that some kind of back-up speed indicator is needed beyond pitot tubes.
- sanj 15y ago
  You've hit the crux of the issue. The aircraft are getting complicated to the point where training in them -- especially outside of "normal" flight regimes -- is difficult. All the references to Normal/Alternate/Direct law are indicative of this. Ever hit the wrong key in emacs and wondered why it was suddenly responding differently? Imagine that happening at 38k feet, at night in a thunderstorm. My doctoral work was exactly in this field. Mode awareness, transitions awareness and autoflight understanding, especially in rare flight configurations, is a deep problem that needs to be tamed. More info in my dissertation (never though I'd write that on HN!): http://dspace.mit.edu/handle/1721.1/9172 http://dspace.mit.edu/handle/1721.1/9172
  - stcredzero 15y ago
    Mode awareness My opinion is that requiring mode awareness is a big chunk of overhead. It should be eliminated wherever possible.
    - sanj 15y ago
      Modes allow you to subdivide the problem space: only certain actions/transitions can occur in a given mode. Removing that restriction allows anything to happen at any time. This is believed to be more complex to model. Think of modes as a mechanism to prune a decision tree.
      - rbanffy 15y ago
        The problem with modes is that if you are wrong about what mode you are in, you'll make wrong decisions.
        stcredzero 15y ago
        I wonder if there's research about mode awareness in crisis situations?
rubyrescue 15y ago
re: third world pilots - that's a big claim with no evidence to back it up. would love to read some if you have it.
- bugsy 15y ago
  Sure, start here, and just keep reading. http://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_commercial_aircraft http://en.wikipedia.org/wiki/List_of_accidents_and_incidents...
  - borism 15y ago
    bullshit reply again? perhaps you can show at least ONE incident that happened because "third world pilots rely too much on autopilot"? I'm genuinely interested, 'cause I'm aviation enthusiast and haven't heard of any.
aschobel 15y ago
> When he came they all continued doing random things indicating none of the three had any flight training that they remembered. Power + Attitude = Performance. Every PPL knows this, as did the three AF pilots that night. They deserve more credit. We know the pilots received an audible stall warning the moment PFD's and STBY ASI failed and the A/P & A/T disengaged. That was a false stall warning, moments later they received another real stall warning. They were flying at night entering turbulence with unreliable and conflicting data with flight control laws that went from Normal Law to Direct Law. The ASI is showing 25+ knots over the max limit while at the same time stall warning is going off. The plane is in direct law mode so any side-stick input could rip it appart. I'm going to wait until more data is released before making a conclusion, there are too many whys.
- lucasjung 15y ago
  I'll start by saying that I fly for a living, and have logged hours in so many different types of aircraft that I've lost count (I suppose I could check my logbook...), everything from bug-smashers to helicopters to supersonic jets (barely more than zero in the helos, though). EDIT: I should also mention that I have an MS in aeronautical engineering, and specialized in stability in control and avionics (the things that went wrong in this mishap)./EDIT I agree 100% with the assessment that the new information does not deepen the mystery, it pretty much explains everything. The quote from gp about lack of flight training is excessive, but it is in the right direction: those guys screwed up big time, and a big contributing factor was almost certainly inadequate training in dealing with emergencies of this nature. They screwed up because their SA bubbles just completely collapsed because they were getting conflicting information from their instruments: simultaneous stall and overspeed warnings. Situations like that are exactly why we still need real, human pilots in these aircraft, because a properly trained crew, who truly understand the systems will be able to put together the clues to figure out what's really going on. A disproportionate amount of my training as an aviator has been dedicated to understanding all of the ways that the systems in the aircraft I fly can break. It's critical to understand not just the common failure modes, but also the interactions between them (what we call "compound emergencies"), especially when following the procedures for one emergency can exacerbate a concurrent emergency. The thin is, in this situation they didn't even have a compound emergency: the only failure was in the pitot-static system. This is an aircraft which requires a sophisticated automated flight control system to remain stable in many flight regimes, and that automated flight control system is utterly dependent on reliably accurate data from the pitot-static system. In that context, these guys should have been drilled heavily on all the ways that the pitot-static system could fail, the manifestations of those failure modes, and how to respond to them. For example: "If you get simultaneous overspeed and stall warnings and your VSI is deeply negative, you are in a stall and need to ignore the overspeed warning and execute stall recovery procedures." Actually, when I word it that way, they shouldn't even have needed special training to figure that out: the VSI should have made it obvious.

by bugsy 15y ago

garyspringer 15y ago

So, are there no pilots in french airlines who also happen to be nephews of people in power?

rbanffy 15y ago

The question not answered is why three trained pilots made wrong guesses as to what was going wrong with the plane. BTW, I imagine a pitot tube placed on the body of the engine would not need extra heating and would be very unlikely to ice. You can even place it inside the exhaust and compensate the reading for engine flow. We have to figure out what went wrong, what mistakes the crew made in order to prevent future accidents like this. And I, coming from a third-world country, take offense at your statement. Pilots here endure very thorough training. One would have to be a lunatic to trust his nephew to a flying computer. The pilot must always know what's going on. And that brings the main point: people die when the machine surprises its operator. "Smart" planes have become so smart pilots have trouble understanding what they are doing under all that software. And that's assuming the software is not buggy and they didn't got a very unfortunate NullPointException in the worst possible moment.

icegreentea 15y ago
I would a pitot tube in exhaust work? There's very little 'normal' air in the exhaust, just the engine exhaust, and unless I got my physics completely wrong, will always give the same relative speed relative to the plane(pivot tube) at any given engine setting... which doesn't tell you anything about the actual airspeed (which is what you need). Pivot tubes are 'tubes' located away from the body of the airplane for the reason that they get away from the boundary airflow to give accurate airspeed readings. Attempting to 'compensate' for other factors just introduces more uncertainty, which is exactly what you don't want when you're 5 knots above stall.
- borism 15y ago
  exactly! Let's imagine a plane starting take-off roll. Engines are spinning up to full throttle (99-100% of thrust), but airframe just started to accelerate slowly. Compensating for anything is pretty useless in this case - airflow trough the engines is even higher than during cruise, but airflow around wings is quite minimal.
- rbanffy 15y ago
  Is the engine airflow at any given regime completely independent of airspeed? I would never use it as a primary source, but it could be used to flag abnormal readings of other instruments.
borism 15y ago
BTW, I imagine a pitot tube placed on the body of the engine would not need extra heating and would be very unlikely to ice. You can even place it inside the exhaust and compensate the reading for engine flow. There are such things in the engines! They're used to feed the data about engine performance to FADECs (http://en.wikipedia.org/wiki/FADEC http://en.wikipedia.org/wiki/FADEC) and the crew. But they're totally useless for airspeed calculation! Bear in mind that air flowing trough and around the engine has totally different dynamics than the air passing around the rest of the airframe. Well, that's kind of the point of the engine - to create thrust, isn't it? That's why airspeed, altitude and AoA sensors actually have to be placed further away from the engines - so that they give as accurate picture as possible.
- rbanffy 15y ago
  Can't you compensate for that? Most of the time planes fly normally - data could be gathered on how to relate the readings of engine management sensors to airspeed. I don't mean using it as a primary source for airspeed data, but backups in case other sources show weird or no data. The data that comes from those sensors already enters the cockpit, so it would make sense to use it.
  - borism 15y ago
    You might be able to, but I imagine the calculations will be very complex and readings will be highly unreliable in anything but ideal conditions and constant speed level flight. But yes, I think the conclusion after AF447 investigation is completed will be that some kind of back-up speed indicator is needed beyond pitot tubes.
sanj 15y ago
You've hit the crux of the issue. The aircraft are getting complicated to the point where training in them -- especially outside of "normal" flight regimes -- is difficult. All the references to Normal/Alternate/Direct law are indicative of this. Ever hit the wrong key in emacs and wondered why it was suddenly responding differently? Imagine that happening at 38k feet, at night in a thunderstorm. My doctoral work was exactly in this field. Mode awareness, transitions awareness and autoflight understanding, especially in rare flight configurations, is a deep problem that needs to be tamed. More info in my dissertation (never though I'd write that on HN!): http://dspace.mit.edu/handle/1721.1/9172 http://dspace.mit.edu/handle/1721.1/9172
- stcredzero 15y ago
  Mode awareness My opinion is that requiring mode awareness is a big chunk of overhead. It should be eliminated wherever possible.
  - sanj 15y ago
    Modes allow you to subdivide the problem space: only certain actions/transitions can occur in a given mode. Removing that restriction allows anything to happen at any time. This is believed to be more complex to model. Think of modes as a mechanism to prune a decision tree.
    - rbanffy 15y ago
      The problem with modes is that if you are wrong about what mode you are in, you'll make wrong decisions.
      - stcredzero 15y ago
        I wonder if there's research about mode awareness in crisis situations?

rubyrescue 15y ago

re: third world pilots - that's a big claim with no evidence to back it up. would love to read some if you have it.

bugsy 15y ago
Sure, start here, and just keep reading. http://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_commercial_aircraft http://en.wikipedia.org/wiki/List_of_accidents_and_incidents...
- borism 15y ago
  bullshit reply again? perhaps you can show at least ONE incident that happened because "third world pilots rely too much on autopilot"? I'm genuinely interested, 'cause I'm aviation enthusiast and haven't heard of any.

aschobel 15y ago

> When he came they all continued doing random things indicating none of the three had any flight training that they remembered. Power + Attitude = Performance. Every PPL knows this, as did the three AF pilots that night. They deserve more credit. We know the pilots received an audible stall warning the moment PFD's and STBY ASI failed and the A/P & A/T disengaged. That was a false stall warning, moments later they received another real stall warning. They were flying at night entering turbulence with unreliable and conflicting data with flight control laws that went from Normal Law to Direct Law. The ASI is showing 25+ knots over the max limit while at the same time stall warning is going off. The plane is in direct law mode so any side-stick input could rip it appart. I'm going to wait until more data is released before making a conclusion, there are too many whys.

lucasjung 15y ago
I'll start by saying that I fly for a living, and have logged hours in so many different types of aircraft that I've lost count (I suppose I could check my logbook...), everything from bug-smashers to helicopters to supersonic jets (barely more than zero in the helos, though). EDIT: I should also mention that I have an MS in aeronautical engineering, and specialized in stability in control and avionics (the things that went wrong in this mishap)./EDIT I agree 100% with the assessment that the new information does not deepen the mystery, it pretty much explains everything. The quote from gp about lack of flight training is excessive, but it is in the right direction: those guys screwed up big time, and a big contributing factor was almost certainly inadequate training in dealing with emergencies of this nature. They screwed up because their SA bubbles just completely collapsed because they were getting conflicting information from their instruments: simultaneous stall and overspeed warnings. Situations like that are exactly why we still need real, human pilots in these aircraft, because a properly trained crew, who truly understand the systems will be able to put together the clues to figure out what's really going on. A disproportionate amount of my training as an aviator has been dedicated to understanding all of the ways that the systems in the aircraft I fly can break. It's critical to understand not just the common failure modes, but also the interactions between them (what we call "compound emergencies"), especially when following the procedures for one emergency can exacerbate a concurrent emergency. The thin is, in this situation they didn't even have a compound emergency: the only failure was in the pitot-static system. This is an aircraft which requires a sophisticated automated flight control system to remain stable in many flight regimes, and that automated flight control system is utterly dependent on reliably accurate data from the pitot-static system. In that context, these guys should have been drilled heavily on all the ways that the pitot-static system could fail, the manifestations of those failure modes, and how to respond to them. For example: "If you get simultaneous overspeed and stall warnings and your VSI is deeply negative, you are in a stall and need to ignore the overspeed warning and execute stall recovery procedures." Actually, when I word it that way, they shouldn't even have needed special training to figure that out: the VSI should have made it obvious.