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Flight 447 'Black Box' Decoded
fermion writes "An initial report has been released by the BEA concerning the details of the last minutes of Flight 447 en route from Rio de Janeiro to Paris. According the report, the autopilot disengaged and stall warning engaged at 2 hours 10 minutes and 5 seconds into the flight. Less than 2 minutes later the recorded speeds became invalid. At 2 hours 14 minutes and 28 seconds, the recording stopped. The final vertical speed was recorded around 10,912 ft/min."
“So, we think that until impact they did not realize the situation, which for the family is what they want to hear — they did not suffer.”
A three minute decent at 10,000 ft/min over the middle of the ocean?
I'm pretty sure everyone onboard knew exactly how that was going to end about half way in.
So far, there is no speculation as to why the airspeed sensors failed or assignment of blame. It is noted that the co-pilots tried to take control and may have stalled the plane. Nothing in the readings contradicts the leading theory of icing on the pitot tubes. It may take a year for a full report.
Well, there's spam egg sausage and spam, that's not got much spam in it.
= 124 miles/hour
Or, about 120mph. (about). Yeah, seeing as that is the vertical speed, i think the passengers would notice that.
I've decided to Diversify my Holdings. I've divided my cash between my left and right pockets, instead of all in one.
What seems to be remarkable is that the trigger to the catastrophe has indeed been revealed to be the pitot tubes - something that was suspected very soon after the flight went down. To a layman like me, it is amazing that without the benefit of all the data that has been recovered from the flight data recorders, experts were able to get so close to the mark.
Now, one could flip this around and also say that given that so many observers were able to so accurately get to the initial trigger for the failure in the absence of hard data, it must mean that this was a really common failure mechanism that should occurred in the field only as a result of the problem being repeatedly ignored.
It is a triumph of technology that the flight data recorder survived under such extreme conditions for so long. It was a triumph of technology, that it was located and retrieved from such an extreme location. Surely, a species with such (magical?) technical expertise could have expended the effort into preventing such a failure?
There is no such thing as luck. Luck is nothing but an absence of bad luck.
A fast, uncontrolled dive? Did they overspeed and get stuck with mach tuck? Other system failures? Regular ScareBus electronic wonkiness?
The only reason I can think of for them not hitting power/attack procedures for faulty pitot systems would be that they were overspeed before they had a chance to fix anything. Perhaps the AutoPilot corrected for an indicated stall and boned everyone on board? I doubt we'll ever know for sure, but automatic systems that can go straight to crap in a half a minute mean persistently alert pilots on long-haul flights. That, frankly, may just be too much to ask.
Wait, how does that compare to the speed of a falling library of congress? They need to give us units we can understand!
Pilots have more skin in the game. Software doesn't really care if it crashes or not.
Truer words won't be said in this thread.
Now the question is, how many air crashes have been due to pilot error versus those due to software error. I suspect software has the better record.
Then he wouldn't have put corrupt manufacturers and regulatory agencies in charge of the airplanes.
I've logged plenty of airmiles, but I'm never climbing aboard one of those hand grenades again in my life.
Irrelevant. A Library of Congress and an Archie comic both fall at the same rate.
This was clearly pilot error.
There are standard operating procedures for this situation, if the pilots had done NOTHING AT ALL, then the flight would have been normal.
Really? I'm not a pilot, but what happens when the auto pilot disengages (as it did in this case), but no pilot takes control? Does the plane keep flying straight and level?
How good is a computer at flying when it loses a key sensor input that tells it the plane's airspeed? Will the computer make the right decision when it thinks the airspeed is 50 knots and the plane is stalling, but in reality is 400 knots?
If it were me, and I only had 3 minutes left, I'd grab a pen from my pocket and carve into my shoulder "4-8-15-16-23-42" to send a message to my family that 'even if the ending sucked, at least I will find happiness in purgatory.'
60 mph is a mile per minute. 10,000 feet is a bit less than two miles. 10,000 feet in one minute is two miles per minute. So, 120 mph vertically. That's a lot. It isn't totally out of reason for a gliding jet though. Big jets have a really crummy glide path. They go down almost as fast as they go forward.
Untrue - a 747 has a glide ratio of about 15:1, so at 30,000 feet, you've got around 80 miles to find an airport if all of your engines fail. Granted, it's a far cry from a 50:1 or better glide ratio you can find in a good sailplane, but it's also far from the space shutle's 1:1 hypersonic glide ratio.
200 km/h is terminal velocity, for a human anyway. I did some indoor skydiving and the airflow is between 190 and 200 km/h depending on how heavy you are. It puts those 300 km/h tornado winds into perspective. Thats more than one G, horizontally.
http://michaelsmith.id.au
Of course, achieving a 15:1 glide ratio requires you to be at the appropriate airspeed to do that... and since the main problem was loss of airspeed indicator, they were falling, not gliding.
its was falling... "with style".
This sig is not paradoxical or ironic.
I trust software more and more in the long run. And I m not a geek!!
If all this is true, it appears the pilots 'froze up; and failed to monitor the instruments that were working properly, namely their HSI or artificial horizon.. 'Partial panel' training, or learning how to fly with what you have left is part of every pilot's training, but under high stress situations like this, it a llgoes out the window, and the result is a form of tunnel vision, focusing on the malfunctioning instruments. This is what happened in the BergenAir crash when its pitot tube was obstructed, and AeroPeru with the taped over static port.. A similar incident happened to Eastern's flight 401 in 1972 when the nose gear down light didn't light up. All three crew members were trying to troubleshoot that and nobody was flying the plane. A very common cause of these things when situational awareness is lost.
For justice, we must go to Don Corleone
According to some media-released transcrips I have read, the plane was stalled for over three minutes and yet the pilots consistently kept the nose of the plane at an upwards angle. Piloting 101 states that if your plane is stalled, the proper maneuvar is to point the nose downwards and dive sharply to pick up enough airspeed so that you can swoop and obtain lift so that you are no longer stalled. Apparently the pilot's actions deviated from this almost universal practice and further doomed the situation.
I am not nor have I ever been the pilot of an aircraft, however I fly remote control planes and I've had to deal with stalls a time or two using such a tactic. If the pilots of 447 had executed such a practice, odds are the stall would have broken. Perhaps that accounts for the 'human error' portion of the blame, but it was significant. I realize that airspeed and altimeter tools are invaluable to flight, but with the loss of those a firm knowledge of aviatic physics can mean the difference between life and death. As it was here.
Of course, in this case, even the computer didn't have the data it would have needed to fly the plane - if the pitot tubes were blocked and not giving a speed reading, the pilots may have attempted to outguess the situation. They may have looked at thrust settings and maybe even GPS speed reports and concluded that there was no stall despite the warnings since they knew the airspeed was far above what was reported.
I trust that an airline pilot has enough training to know how to handle a stall, but if he knows his instruments are lying to him, then he may choose to ignore them.
Do stall warnings use anything other than airspeed and angle of attack to warn about a stall, or are there some type of sensors on the wings to detect airflow and lift?
So far, the NOVA summary is on target. In addition to the pitot tubes freezing, which is an obvious design flaw, it sounds like the pilots reacted improperly to the loss of speed data.
Will the computer make the right decision when it thinks the airspeed is 50 knots and the plane is stalling, but in reality is 400 knots?
Yes, it will detect that the speed measurements it is getting make no sense. It will disengage and let something whose sensors are still working take over, that being the pilot. That is what the right decision is.
What is not clear is why the pilots nosed up in a stall, even when getting stall warnings. It may be possible they did not know their altitude and thought they were low, or for some reason they distrusted the stall warnings they were getting. Given that the autopilot shut down, they may have assumed the worst about their instruments.
Merely losing air speed really shouldn't result in a crash.
Unless some other system failed, this might be a case of pilot error due to vertigo.
The Garmin GPS I use while driving tells me how fast I'm going.
Your GPS tells your speed relative to the road, which, being firmly attached to the ground, is the speed you care about.
However, in a plane, your GPS tells you your speed relative to the ground, which could be plus or minus 300mph from your airspeed (depending on the speed of the jetstream) and I imagine that in the stormy conditions they were in, wind gusts could have made their airspeed even more variable and unpredictable with respect to ground speed.
i think what parent is saying is that the pilot put the plane's nose UP, actually creating the fatal stall. If left to fly level, the plane may have recovered.
The Cloud - because you don't care if your apps and data are up in the air.
Pilots simply do not know how to fly anymore
Yep. Send them all out to do spins in a sailplane. Twice a year.
http://michaelsmith.id.au
bah: 333,312 furlongs per fortnight
In the plane, stall buffet is impossible to ignore. Anybody who has flown a light aircraft will know to push the nose down. Unfortunately flying is more about filling in the forms and programming the onboard computer these days. Maybe the plane is at fault, by not making the pilots fly all the time.
http://michaelsmith.id.au
Software can be made to be very safe and takes care of a lot of things in airliners these days. In theory, it is more than good enough to take off and land the planes on its own already.
However, when the software has not been programmed to deal with an unusual case, it will simply not work. For software, there really is no try, there is either do or do not.
Its failsafe is to complain about it very loudly and have something which can adapt better take over for it: a pilot. Someday we may have AIs in planes, or at the very least, very, very advanced expert systems, and pilots really will be obsolete and maybe even unsafe to have relative to the abilities of the system. That day is not quite here yet, since the difference between pilots and software is not enough so that the general public stops believing the humans are far superior in the cockpit.
1. Unless it's pressurization system was faulty (it wasn't) the pressure change wouldn't have been great.
2. Unless accelerating, you wouldn't know you were going down (or up, or banked or upside down...).
So the claim that the passengers probably didn't think it was anything more than turbulence is not hard to believe.
This pre-supposes that the passengers felt approximately 1G of gravity downward from their point of view, which pilots normally carefully maintain for passenger comfort. A banked turn that maintains 1G of gravity downward by carefully controlling the turn rate feels "normal" as if the plane were flying straight. Pilots can't do this in an emergency when there are systems failures.
Remove that 1G of gravity like in a free-fall, or flying straight down, and the passengers are going to become acutely alarmed very quickly. Normal turbulence of sufficient magnitude can do this -- and the conditions they were in were worse.
So put your thinking cap on for a second, and consider how it might be possible for a plane flying directly downward to somehow create 1G of gravity sideways such that from the point of view of the passengers, they feel 1G "downward". How is that possible? The only way that could be done is through centrifical force, such as if plane were pulling up, and if it's flying strait down, it's not pulling up. At best, the passengers felt gravity at their backs from the acceleration downwards. As soon as they reached terminal velocity downward, the gravity they felt would be 1G to their front. I'm quite sure that as a passenger I'd notice all of that.
I think this was three minutes of terror for everybody on that plane.
Of course, of course, they didn't lose engine power, so glide ratio has nothing to do with this particular incident...glide ratio is not what dropped this plane into the ocean.
The parent poster claimed that a 10,000 ft/minute drop is within reason for a gliding jet, which is not the case unless there are other mitigating factors, like loss of hydraulics.
I have been reading the report and there are some strange interesting passages. Here is a partial summary, focussing largely on pilot control inputs
Copilot is PF. Captain is PNF.
2 h 08 min 07: "...turbulence increased slightly and the crew decided to reduce the speed to about Mach 0.8"
2 h 10 min 05: "...the PF made a left nose-up input. The stall warning sounded twice in a row...Autopilot and auto-thrust remained disengaged for the rest of the flight."
2 h 10 min 16: "...The airplane’s angle of attack increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs... The airplane was then at an altitude of about 37,500 ft"
At 2 h 10 min 51: "...The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs...The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight...The PF continued to make nose-up inputs."
2 h 11 min 40: "...The airplane’s pitch attitude did not exceed 15 degrees and the engines’ N1’s were close to 100%..."
At 2 h 12 min 02: "...At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs..."
This much seems clear: the airplane was cleared for flight level 350 (35000 ft), and was likely at that altitude when the trouble started, assuming the altimeter was functioning. Stall warnings went off, and the airplane climbed to 38000 ft. It then descended rapidly, it seems with a monstrously high angle of attack. It also seems from the report that the nose of the plane was mostly pitched up through this, though I am not absolutely sure on this. This would imply a very bad stall...essentially the airplane was falling from the sky. One can speculate that the pilots were doing their best to recover from the stall with imperfect data on their airspeed.
To me the important period was between 2 h 08 min 07 and 2 h 10 min16. There was a decision to reduce speed, which would entail a reduction in thrust. Two minutes later, there was a stall warning, implying that the airplane's airspeed was out of the very narrow range required at that altitude (plus/minus 10 knots according to the Nova documentary, though I'm not sure it's so narrow). The question is, what caused those initial stall warnings? How did the airplane's speed get out of the proper range? Did the pilots forget to increase thrust after the autopilot reduced it? During those two minutes, was the airplane catastrophically slowing down?
This and no other is the root from which a tyrant springs; when first he appears as a protector - Plato (423 to 327 BC)
1. Unless it's pressurization system was faulty (it wasn't) the pressure change wouldn't have been great.
2. Unless accelerating, you wouldn't know you were going down (or up, or banked or upside down...).
Unfortunately, you're right -- because they were stalled but yet relatively level, the passengers felt 1G downward as if they were in normal flight. So they had a brief rough ride during the initial stall, but then after they seemed to "recover" and reached terminal velocity, they felt 1G and as if everything was normal.
What's most interesting in this case is that the systems warned the pilots of an impending stall, but then once they were in a stall, there was no warning at all, as if they had recovered from the stall. That's really unfortunate.
Airbus is run by software. Boeing by pilots. I don't trust either, but I trust the software less
I bet there is some software in Boeing aircraft, and I bet there are pilots in Airbus aircraft too. It will be interesting to see what the final report says that software and/or pilots could have done, if anything, to avoid this crash, even with malfunctioning speed indicators.
Only in a vacuum.
TODO: Something witty here...
The problem for your description, of course, is that the plane wasn't flying directly downwards, or anywhere close to that.
"Convictions are more dangerous enemies of truth than lies."
To quote TFA,
The airplane’s angle of attack increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied between 12 degrees right and 10 degrees left. The speed displayed on the left side increased sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees.
From 2 h 10 min 50, the PNF tried several times to call the Captain back.
At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, of around 6 degrees at the triggering of the stall warning, continued to increase. The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight.
This and no other is the root from which a tyrant springs; when first he appears as a protector - Plato (423 to 327 BC)
Airbus is run by software. Boeing by pilots.
This is a delusion. Read up on Turkish Airlines Flight 1951. I mean, they programmed 737 to do what? Trust a single radio altimeter known to fail in the worst possible mode, producing false readings? Actually use these readings to automatically enter the landing flare mode with rather subtle indication to the pilots? Autothrottle reverting pilot's inputs? Sounds like scary automation to me.
The reality is, all modern commercial airliners are run by software. If you want an airliner run by pilots, go to Russia and fly some Tupolevs, there are still quite a few left (ehhehe).
My exception safety is -fno-exceptions.
Do stall warnings use anything other than airspeed and angle of attack to warn about a stall, or are there some type of sensors on the wings to detect airflow and lift?
IANA-aeronautical-engineer, but I imagine that you cannot easily determine the actual angle of attack w/o sensors to detect airflow. The actual angle of the wing referenced to the ground (or other fixed reference) doesn't determine the angle of attack, it is relative to the windspeed around the winds. Thus the angle of attack is mostly inferred by sensors that measure windspeeds (mostly). AFAIK stall warnings often additionally use measurement devices that measure dynamic differntial pressure around (or nearby) the lift surfaces (aka LRI), and other secondary indicators (e.g., buffeting dynamics of the plane when it nears the stall conditions).
Which is 55.4m/s or 200 km/h
When our name is on the back of your car, we're behind you all the way!
Assuming the average length of a book in the Library of Congress is 300 pages and it takes 3 minutes to read one page, this decent rate can best be expresses as 725,254,818,816 FootballFields/LibraryOfCongress
I swear to God...I swear to God! That is NOT how you treat your human!
The problem for your description, of course, is that the plane wasn't flying directly downwards, or anywhere close to that.
Yes, you're right. I "RTFA"'d, but the actual article didn't explain this -- only the original report did. I made a second reply stating this, but didn't reply to my OWN comment to make it clear I had been wrong in my first post.. :-/ Best thing I can do now is to at least admit my original mistake.
10,000 ft/min = 120 miles/hr & looks suspiciously like a flat spin.
I'm reading your citation, but it doesn't seem to support your claim... HULL LOSS ACCIDENTS:
A320: 0.34 per million departures
737-300/400/500: 0.52 per million departures
737-600/700/800/900: 0.21 per million departures
A330: 0.27 per million departures
767: 0.39 per million departures
777: 0.21 per million departures
A380: too few to judge
747-400: 0.49 per million departures
It looks like, in each class, the airbus is better than the old boeings, but not as good as the new boeings.
depending, I think, a bit on how each is boxed.
Computer memory is just fancy paper, CPUs just fancy pens with fancy erasers; the 'net is just a fancy backyard fence.
You know how easy it is, when down is a sum of gravity and torque.
Computer memory is just fancy paper, CPUs just fancy pens with fancy erasers; the 'net is just a fancy backyard fence.
Also known as "free fall" or "we are fucked".
I trust software more and more in the long run. And I m not a geek!!
That's why.
Piloting 101 states that if your plane is stalled, the proper maneuvar is to point the nose downwards and dive sharply to pick up enough airspeed so that you can swoop and obtain lift so that you are no longer stalled.
That's why I think that there *must* be more to the story. It is simply not possible that anyone with a pilot's license, especially for a heavy jet, could respond to a simple stall by raising the nose.
--M
# grep slashdot access.log | grep html | sort | uniq | wc -l 2604
The reality is, all modern commercial airliners are run by software.
This.
That "Boeing yay, Airbus nay" fanboyism only makes the fanboy look stupid really.
Boeing builds perfectly fine aircraft. Airbus builds perfectly fine aircraft. Get over it.
Airbus is run by software. Boeing by pilots. I don't trust either, but I trust the software less
Not only is your statement a grotesque and erroneous oversimplification that betrays your appalling ignorance of these matters on any number of levels, your post isn't even relevant to this discussion, because this particular Airbus was under the pilot's direct control when it crashed.
If, as seems likely, the aircraft's airspeed sensors began to fail due to pitot tube icing, the autopilot and autothrust would disengage, and the confusing sensor outputs would have kicked the aircraft over into one of the alternate control law modes. (Based on the cockpit chatter and sensor logs described in the report, this is exactly what did occur.) Among other things, the alternate control laws would give the pilot significant latitude to take actions - even actions that seemed 'wrong' - because the onboard computer was aware that its sensor inputs were compromised.
~Idarubicin
Are all up in arms that the computer crashed this airplane. That is 100% incorrect. The computer dropped offline and the pilots had to take teh controls. That is what crashed this airplane and most modern airplane crashes. Pilots simply do not know how to fly anymore.>
But, uh, the computer didn't know how to fly in those conditions either; that's why it gave control back to the pilots. This is the real problem, pilots are taught to trust the computer 99% of the time, then when things get really bad they're expected to suddenly take over.
Other crews have survived loss of airspeed indication in an Airbus, but I believe this is the first time it's happened in bad weather at night when disorientation is highly likely.
Think about your statement for a moment. Just THINK. Your point 2 is completely bogus. If you were strapped in a seat blindfolded and stationary or moving at constant speed, and the seat is rotated upside down, you wouldn't feel the difference? With your seat belt cutting into you with your full body weight? Really?
It's entirely possible to be upside down AND ACCELERATING at negative 2G and THEN you wouldn't be able to tell you were upside down, but that's not what you said.
It's just a quibble but an important one. Yes, without visibility you can't tell the difference between acceleration and attitude change.
Actually, they know the that the autopilot disengaged due to the pitot tubes from error code data that was transmitted from the plane to a satellite then to Air Bus before the crash. What they did not have was other telemetry like, power settings, speed, positions of the control surfaces.
P226
It's randomly on a car forum, but its worth a read. Some guys that know what they're talking about talk about what they think happened. They also include pics of various airbus cockpits for reference.
http://www.mye28.com/viewtopic.php?t=64381&postdays=0&postorder=asc&start=25
Here's the basic story, as I understand it:
- the pilots flew into a thunderstorm
- they were 100% blind, relying entirely on the glass-screen instruments
- once all 3 pitots froze, the redundant computers started disagreeing and then finally agreed that things were ugly
the effect in the cockpit is that a serious of cascading failures were unfolding, likely overwhelming the pilots.
additionally, there would be NO functional indicators for alt, speed, horizon, etc. Once the computers have faulted, they no longer share that information.
Also, as the computers degrade authority, in an Airbus the pilots get MORE control of the aircraft. This means that controls move through larger ranges.
As flight control reverts to failsafe mode, the controls in the cockpit do not "auto-zero". And the forcefeedback goes off line.
Effectively, the pilots are 100% blind, and the inputs they make have no feedback whatsoever. They cannot even tell if they have _stopped trying_ to turn.
Imagine being blindfolded. Your job is to put the end of a 4 ft long stick inside of a 1" circular hole in the floor. Except the stick is a peice of yarn.
That's what their instruments and control apparatus were like.
Now imagine that everything is beeping at you and you are in a plane in a thunderstorm, over the ocean, at night, and everything outside is total blackness.
You're fucked. Thoroughly and completely fucked.
My opinions are my own, and do not necessarily represent those of my employer.
The actual BEA report, which should be read before commenting, does not assign blame. That will come later.
At one point, the left side airspeed display showed 215 knots, far above stall speed. The backup airspeed indicator showed 185 knots, also above stalling speed. The right side airspeed display value isn't logged. Then all speeds showed as invalid. Given that conflicting information, at night in a thunderstorm over water with no outside visual cues, it's not totally unreasonable that the pilots, finding themselves losing altitude but thinking they had more airspeed than they did, tried to pull up.
I believe GPS fixes your position in 3D space, difference in successive fixes can be crunched to yield speed and direction of travel.
So it would not matter if you were on a road, or there is a strong jetstream on an aircraft.
There is no question that GPS can calculate your ground speed and heading with great accuracy (usually).
However, the more important speed for flying an aircraft is its speed relative to the air, i.e. the airspeed. Speed relative to the ground is nice to know for calculating ETA to the destination and fuel reserves, but it's the airspeed that matters to the control surfaces.
If the GPS says that the airplane is traveling west at 200 knots and there's a 150 knot tailwind from the east, the effective airspeed is 50 knots - that's the speed the pilot wants to know and he won't find out from the GPS. Add in variable gusts from a storm system, and it makes it very difficult to fly the plane without airspeed indication.
I dont understand why attitude indicators would fail to function with clogged pitot tubes, (and even statics). Also you can't tell airspeed, but from gps ground speed you should still be able to tell roughly how fast you are going. So with ground speed and artificial horizon it should be still flyable. Not easy but flyable.
Good points.
"What luck for the rulers that men do not think." - Adolph Hitler
It seems very scary that on an aircraft with everything working but the airspeed indicators (and I understand that those are very important), after more than 3 1/2 minutes the aircrew was unable to prevent the plane from hitting the ocean. This was a state of the art aircraft. Makes you wonder how many close calls there have been that luckily didn't result in catastrophe.
Airbus is run by software. Boeing by pilots.
That continues to be true with existing aircraft and designs. It had less to do with the two companies have a huge philosophical difference than the fact that Airbus had a lot of clean sheet designs and Boeing did not, and it was easier for Boeing to not use fly-by-wire.
When Boeing does do a clean sheet design (777, 787 and maybe the replacement for the 737) it adapts fly-by-wire and the systems are more or less equivalent to how Airbus aircraft are flown.
A pilot friend once told me that most cockpit recordings leading up to a crash start out with "Oh shit!!!" and end a few minutes later with "Oh. Shit."
From the report:
The angle of attack is the angle between the airfow and longitudinal axis of the airplane.* This information is not presented to pilots**
*This much I already knew...
** A missing feature in new airplanes, possibly specific to Airbus.. and it totally sucks! How could they leave something so important out??? What assholes!
For justice, we must go to Don Corleone
It seems to me that the pilots knew something was wrong, and had over 3 minutes in which they (he?) tried to handle the situation. I'm surprised that they did not issue at least a panpan to air traffic control. It wouldn't have changed the outcome, but might have helped with the search operation.
Shachar
I find it highly unlikely that clogged pitot tubes would take out all the static and gyroscopic instrumentation too. That would be a phenomenally stupid design, and would rank the Airbus lower than a Cessna 150 in terms of instrument reliability.
The information in the report is preliminary, and there has to be more to this story. Even the lowliest weekend warrior pilot earning the most basic instrument certification has to demonstrate an ability to fly in IMC with multiple instrument failures.
What I want to know is why the PF pulled the stick back to the stop with the stall warning blaring in his ear. There's no way an airline pilot would make such a stupid mistake—unless there's way more to this story than what we're reading in the preliminary report.
So there are no gyroscopes telling them if they are level? That can't be right. Here is how it should have gone (according to my mind (read: fantasy)):
Everything except the gyroscopes (and radar altimeter?) went to hell and started blinking and making loud raucous noises designed to increase the panic level. The pilot walks in from his nap and authoritatively shuts all the damned noises off and does a quick assessment of the situation. He or she decides that, "this is some fucked up shit", and goes into guess mode. The pilot then levels the plane according to the gyroscopes and then applies 5% more thrust than a typical cruising speed would require. Prayers are then submitted to the appropriate deities that they will get out of the thunderstorm and/or the computers stop acting crazy before something Really Bad (TM) happens.
I am guessing what really happened is that everyone had a massive panic attack and tried to act on what they thought was happening and flew the plane directly in to the ocean.
MoooOOOOooo
"Someone needs to talk to the tree of liberty about its ghoulish drinking problem." by ohnocitizen
Read the thread, where the pilot describes, based on the stored faults, which instruments and displays are now offline / not showing what they're supposed to.
The pilots had NO idea of attitude or speed. Even if there were systems onboard that were accurately capturing that data, the crew were not seeing it.
To me, that does seem like a serious fault.
If the pilots had been in day time conditions, and stayed within the (now, non-range limited) ranges of the control surfaces, they'd have been fine.
My opinions are my own, and do not necessarily represent those of my employer.
Correct, there were no instrument displays telling them they were level. The computers that decide that information disagreed with each other and gave up.
If you aren't a jet pilot, I would probably stop suggesting how it should have worked. Your suggestion to apply 5% more throttle could have destroyed the aircraft.
One thing I learned from this thread is the "Coffin Corner". Flights are operated very near the intersection of their absolute altitude and their absolute vmax.
This puts them in bad shape -- if they go faster, they exceed the design speed of the aircraft. This can cause things like mach tuck and cause the control surfaces to stop responding correctly. Nobody wants a plane that becomes aerodynamically unstable AND doesn't respond to controls.
If the overspeed is excessive of course the aircraft fails structurally.
If they go too slow, obviously they stall.
For a loaded Airbus operating at say FL350 and mach .8, there may only be a 30 knot range of permissible airspeeds. The auto throttles ("cruise control") will attempt to maintain a set speed within that range. THe upper and lower bounds are constantly changing based on atmospheric and flight parameters..
Note that its not as easy as hitting the gas or the brakes -- aircraft attitude greatly impacts speed, as does its altitude.
The planes fly high because it saves gas, its quiet, and its fast. But there isn't a big margin for error up there.
So without having ANY idea how fast you're going, where you're pointed, or what your altitude is, its grossly irresponsible to just apply more throttle.
The only safe course of action is to try to get to lower atltitude somehow without overspeeding the aircraft. But again, how do you do that if you don't know how high you are, where you're pointing, or how fast you're going?
It's basically bullshit to blame the pilots for what happened here.
My opinions are my own, and do not necessarily represent those of my employer.
WRONG WRONG WRONG FUCKING WRONG!!!
All Airbus cockpits have "old fashioned" analog devices, in particular the artificial horizon. Also, there is no force feedback on the sticks.
Please don't spout crap about an aircraft that you know nothing about.
If you lose the computers the aircraft flies like any other normal aircraft. You are not fucked in anyway.
This is more like a complete loss of situational awareness by the pilots - actually a very common problem that is independent of the aircraft type, manufacturer and whether is the "computer" controlled (whatever that fuck that means). Similar things happened to the Turkish 737 crew who crashed at Amsterdam a few years back, the Cali 757 accident, the Strasbourg A320 crash etc etc
ps: I fly an E170/190 for an airline that also happens to have A320s ....
Good luck getting an artificial horizon or GPS when your computer systems have voted each other off the island and are looking for their towels. :)
It surprises me that things are set up this way. These flight control systems are set up as multiple-redundant systems, and yet a single failure (pitot tubes icing up) can lead to an information blackout.
Also, it's still possible for the instruments to give incorrect information because they rely on sensors that measure secondary effects (e.g. altimeter based on air pressure, measuring height above an assumed sea level instead of a direct altitude measurement by radar).
It seems to me that there should be a second, independent path for the essential information (position, attitude, speeds in all dimensions). I know GPS has its faults, but it would provide a useful backup for position and speed and give the pilots more information than the primary instruments can. That leaves attitude information, you can use a gyro-driven artificial horizon for that.
Where are your errors?
Air industry fanboying is retared. Both the main manufacturers in the western world have excellent safety records, with the difference in the (tiny) number of hull losses to small to draw conclusions from.
If we can put a man on the moon, why can't we shoot people for Apollo-related non-sequiturs?
As I understand it, the air speed is determined by a little tube sticking out of the nose of the aircraft. This tube got iced up, they couldn't determine their airspeed, and the crew were not able to keep the plane flying without this information.
But can't a modern plane determine its speed through GPS measurements?
If we can put a man on the moon, why can't we shoot people for Apollo-related non-sequiturs?
If Air France's A330-300 are set up the same as SAS' (430KB PDF), there should have been a cluster of mechanical backups just to the right of the pilot's primary glass displays, including an artificial horizon. Even if the backup sink rate, airspeed indicator, and altimeter were returning bogus values, the gyroscope and compass wouldn't, and ergo there would have been at least enough information to know which way the bird was pointing.
Luke, help me take this mask off
Just wondering if a (backup) of GPS would have helped in this situation. IIRC the altitude accuracy of existing GPS is not brilliant, but surly it would have been useful ?
This is a pretty interesting comment, insofar as that I recall that right after the accident, lots of accusations were slung at Airbus about how the abundance of computers and electronics in their planes was the culprit (and naturally, good ol' American companies like Boeing would never had problems like this, what with putting control in the hands of real, manly men). Now suddenly, it's the computers turning off and the pilots getting more control instead - Airbus is being blamed again, for the exact opposite.
I don't know a thing about planes myself, and maybe one of these positions actually has merit, but I sure am able to see that they're incompatible, and I'm gonna take them both with more than a grain of salt. Speculation from laypeople and armchair experts is bad enough; speculation from actual experts who nevertheless weren't there, don't have the data, don't know a thing etc. can be even worse.
Alt. must have worked it is recorded correctly by the black box, I see no reason to believe horizon shouldn't have been working, so only visual and speed was impaired. That is still a difficult situation, so no reason to exaggerate it.
If you are not rolling gravity will always point down. But because he was in a roll due to the constant circular acceleration of the plane the tea accelerated toward the bottom of the glass (same idea as with space stations in ring form turning on themselves along the spindle to have artificial rgavity, I guess you would call that a centrifugal force).
In a *NON* roll situation, that is if the plane was flying on the BACK, or vertical toward ocean, the cravate trick or anything ina glass would fall/pour toward the center of earth. So yes, what the grand parent said is right, and your roll video is only at best an exceptional example where *additional* acceleration make the result different.
Since AF447 was not rolling as far as I udnerstood the reports, then yes, passenger would have felt or remarked that something was wrong in a quasi vertical final descent.
C. Sagan : A demon haunted world:
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visit randi.org
Serious question: I understand that in the event that the highly accurate onboard instruments fail or become unreliable and the computer decides this information shouldn't be piped to the pilots consoles why doesn't it switch to a best guess mode? By that I mean something less reliable, but possibly life saving, say a gps receiver mounted on the nose and tail of the plane. It could give an estimated height and if the receivers are getting a clean enough signal should be able to indicate to the pilot his rough angle in the sky. Seems like that would be better than what happened here.
the pilots flew into a thunderstorm
What we can assume is that they expected only a slight increase in turbulence. The pilot in control of flying the plane told the cabin crew: "in two minutes we should enter an area where it’ll move about a bit more than at the moment, you should watch out". They also made a left turn shortly after that in hopes of avoiding even that, and then the turbulence "increased slightly". As for visibility, they probably had no visual references prior to entering the storm. For instance, as far as I can tell with Celestia the moon was not visible from their location at 0200 UTC on 20090601.
once all 3 pitots froze
We only know for sure that 2 of the indicated airspeeds were incorrect at some points, probably due to icing in the pitot tubes. The third was not recorded.
the redundant computers started disagreeing and then finally agreed that things were ugly
the effect in the cockpit is that a serious of cascading failures were unfolding
Yes, the speed inconsistency lead to the following among other things:
- alternate law in effect (see below),
- autopilot disconnecting, and
- autothrust disconnecting (although I understand the engine thrust would have stayed the same at this point until a pilot altered it).
likely overwhelming the pilots
This is pure speculation at this point.
additionally, there would be NO functional indicators for alt, speed, horizon, etc.
Wrong. There's no evidence to support malfunctioning fundamental indicators other than loss of airspeed indication, and perhaps the somewhat inconsistent stall warning.
Once the computers have faulted, they no longer share that information
See previous point.
Also, as the computers degrade authority, in an Airbus the pilots get MORE control of the aircraft.
This is a fair statement. They degraded into alternate law.
This means that controls move through larger ranges.
More or less so (stalling etc. possible), but the computers still have an intermediary role so for instance they could not go beyond max G loads in this particular mode.
As flight control reverts to failsafe mode, the controls in the cockpit do not "auto-zero".
Are you talking about auto trim? Auto trim was still available, as shown in the report. (If the aircraft had degraded into direct law, it would have been disabled.)
And the forcefeedback goes off line.
There's no force feedback that I'm aware of, other than a stick shaker during indicated stall.
Effectively, the pilots are 100% blind, and the inputs they make have no feedback whatsoever.
The report clearly states that the engines responded, and the report seems to be consistent with the aircraft responding to all "mainly nose-up" inputs by one or both pilots. What was displayed to the pilots was inconsistent for a time, yes, but again many of the instruments may never have failed at all.
They cannot even tell if they have _stopped trying_ to turn.
What do you base that on? Again other than the stall warning and airspeed indications there is every reason to believe that many if not all other instruments were working, such as:
- Information from GPS etc. (such as g
If you want me to take your words seriously, please don't use a patronizing attitude next time.
Cheers.
Metric people, please...55 meters per second or 200 km/h. That is about 108 knots, if you want to use avionic Empiric measurement units. If you're comparing to US road speeds, 136 Mph. Try driving your car into a stack of water barriers at 136 Mph and figure what happens to it and the people inside if you want to make it sound dramatic. Coming up with feet per second just so you can dramatize the story with a large number, is something that should be reserved for FOX news.
I was promised a flying car. Where is my flying car?
I'm trying to convey to you what I understood from that thread. I apologize if I've gotten it wrong.
The pictures show several different A320 instrument setups. I see no artificial horizon instruments, but then again I may not be seeing them.
Furthermore, the pilot pointed out that while there is an "emergency instrument" system, called "ISIS", I beleive, it gets its data from the same place, and would also have been offline based on the recorded faults.
My opinions are my own, and do not necessarily represent those of my employer.
My information suggests that the sensors feeding the black box either cannot or were not made available to the primary flight instrument computers, astonishingly enough.
Given the amount of system isolation in aircraft this isn't entirely impossible to beleive. If you tie part B into part A's wiring in any way, you have to do more testing/verification than you would otherwise.
My opinions are my own, and do not necessarily represent those of my employer.
You should also read the latest thread at Airliners.net. There are several Airbus and Boeing pilots who post regularly.
The problem is that everything is shown as normal until WAY after the time that everything has turned to sh*t. The autopilot is engaged, and the speed sensing goes screwy (probably over the time of a few minutes) with the aircraft correcting for speed and pitch all the time. In a thunderstorm you will always see big changes in power settings and attitude, but the airspeed will be kept relatively stable by the autopilot.
When the pitot tube freezes up (or possibly the static ports as well), the airspeed may appear to fall or climb, based on exactly the conditions that are in the tubes/static ports and which part froze over first. If the static ports ice over then altitude sensing also gets quite interesting/fails. The autopilot tries to follow the the set airspeed/altitude, and corrects the pitch and engine settings to compensate. The plane has gotten itself into the beginning of a dangerous attitude, and around that time the computers finally give up and stop giving any sensible information.
You have a heavy jet, possibly with engines spooled down, in a high pitch attitude, with no reliable sensors, no feedback to the controls, and in a thunderstorm. Now the pilots have maybe 10 seconds to decode the situation before a massive stall of the wings, and possible inlet stall of the engines in the following violent maneuvers. The plane stalls.
Even if the pilots were able to make sense of the situation they had almost no chance of doing anything. The only backup instrument that may possibly be giving useful information is the artificial horizon, but the pilots can't know that; they look to the backup airspeed indicator, altimeter, and climb/descent indicators. All of which are telling lies.
They have seconds to judge what is going on, but it requires serious armchair speculation to see what is the correct course of action. They didn't have that luxury.
The above is, of course, a hypothetical armchair strategist's interpretation of the situation. I do have the advantage of having been a commercial pilot, but it is still pure speculation.
I am reminded of a Crash that was found to be caused by a taped over intake for the altimeter, resulting in the crew not knowing how high they where and getting, to them, odd warnings about low altitude.
comment first, facts later. http://chem.tufts.edu/AnswersInScience/RelativityofWrong.htm
Thanks for posting that URL http://www.mye28.com/viewtopic.php?t=64381&postdays=0&postorder=asc&start=25 I now know more about Airbus FBW systems than ever. The comments on the thread by the Airbus pilot are extremely informative and based on a sound knowledge of the aircraft and its systems.
Sigs. We don't need no steenking sigs.
This is correct as far as the response of the glass instruments, but remember that the airplane includes a full suite of primitives (pitch indication, among others).
The trained response for an Airbus pilot of this aircraft in a loss of awareness is to neutral the plane. Set the throttles to 85% N1 and point the aircraft at +5 degrees. This is the neutral position for that Airbus and will keep a safe altitude and speed until the platform returns. The pilots were trained to do this.
I'm all for it! (I'm an A320 pilot).
Except if the manufacturer of the airplane told you so. Because, you know, Airbuses never stall. If you pull back all the way, it will fly the maximum angle of attack. Except in alternate law, but there's no need to do too much training on that, right? At least, not according to Airbus.
The attitude indicators remained valid, so did the altimeters (but can you trust them if airspeed is faulty and both are from a similar source?), there's no forcefeedback in an Airbus, but the bit about everything beeping at you in a plane in a thunderstorm at night etc is probably pretty accurate.
They lost airspeed indications, but did they have altitude readouts? Attitude indications from a gyro? Angle of attack (not quite the same thing as attitude)? If they had a "partial panel", would they have had reliable indications of what was "good" what readouts were wrong?
Actually read that whole thread posted by bmajik from page 2 on. Its quite interesting.
But most especially the posts by TSMacNeil who is an Airbus pilot. (One thing was made abundantly clear by reading the thread -- any interpretations of this data from bystanders who are not Airbus pilots are likely to be nonsense and can safely be discounted. "I have a pilot's license" is worse than meaningless in a discussion like this).
http://www.mye28.com/viewtopic.php?p=863682#863682
http://www.mye28.com/viewtopic.php?p=865321#865321
Not quite. The root cause here is the thunderstorm. Famous sentence here: “There is no reason to fly through a thunderstorm in peacetime". Any pilot knows that entering a Cb cloud (thunderstorm) is basically comitting suicide. Now, if on top on that you're losing your speed indicator, then you're really fucked up, but you called for it. Losing the pitots in clear air is just annoying. Entering a Cb is suicide. Losing the pitots in a Cb is just going to kill you quicker...
I am not a pilot. I am a regular commercial airline passenger, a so called "frequent flyer", sometimes internationally; all of which often involves taking long night flights over ocean and into undisclosed/random weather.
I like the flying itself, but for the last few years I have avoided casual air travel for two reasons :
1. the airlines for their miserable attitude to passenger comfort and schedules
2. airport/security for their poor facilities, ludicrous security theater, cumulative irradiation and civil rights violations.
Reading this discussion, and writing simply as a passenger, I conclude that the equipment on planes and the capabilities of a regular airline crew are inadequate to prevent a modern airliner from simply flying into the ocean, given what seems to be a very common set of conditions. I appreciate that this is an interim report, fair enough, but are we simply hoping it does not happen again?
I now have a new reason to avoid flying - a credible, common, and yet apparently unmitigated risk:
3. A generic airliner (it's just another passenger vehicle to me), experiencing common high altitude flight conditions, with a nominal/average crew, may kill everyone on board, because the flight control protocols cause the crew to fly it into the ocean.
Is there any clear and credible statement by the airline industry as to what they are doing to prevent this from simply happening again? What have they changed so that more people wont die, the next time this set of circumstances occur ?
I am guessing many people will want to tell me I am wrong to be concerned; if so, that's a good thing, but please explain why, in simple terms a frequent flyer can rationally believe. IMHO, "The next crew won't do the same things..." seems a bit too optimistic and basically unprovable to me...
What has been changed to prevent this tragedy from re-occurring ?
There is no god; get over it already! Never exchange a walk on part in the war, for a lead role in a cage.
This is probably a very stupid question, but I'd still be grateful if an expert could chime in.
It's not hard to detect big storms, either from land-based radar or aircraft-based radar. If we can do that, then why can't we just fly around them? Sure, it'll mean a long delay, but modern airliners are bound to have enough fuel to cope with it, and being late but safe is probably a good tradeoff for most people. After all, 50 years ago, flights were regularly delayed due to bad weather -- I mean by days -- so why can't we tolerate, say, a 6-hour delay in a transatlantic flight to evade a storm?
Nova had a program on Flight 447, which I watched several months ago. I am not a pilot, and I'm going from memory.. but what I recall seems quite close to the new black box data. Their theory focused on the Pitots freezing up, making the computer unable to fly the plane.
A difference from most comments here: I believe they said the Pitots were heated (wouldn't ALL pitots have to be? It's always freezing at altitude), but there was a super-cooling possibility with very pure water which could surpass the heating ability. The comments here sound like the pitots were not heated and/or known bad.
They also put a pilot in a flight simulator in that scenario -- lost air speed data, stall warnings -- and he had no problem controlling the aircraft and maintaining level flight.
All aircraft have a "safe-mode" angle of attack and throttle setting that would ensure stable and safe flight until they could figure out what was going on.
As long as their gyros were working (which they most certainly were, hello redundancy), they should have pulled through this as other flights that go through this ALL THE TIME have....
The flight envelope in this case apparently only has about 30 knots of margin so ground speed is not sufficient.
The procedure in this case is to set the engine throttle to a specific power and maintain attitude for a given altitude which will yield an acceptable airspeed but for whatever reason that did not happen.
Note: this post I made is incorrect -- so this is a retraction. :-/ And unfortunately since the stall warning ceased, they THOUGHT they had corrected for the stall.
The aircraft was IN A STALL but yet level, so when they reached terminal velocity, they actually DID feel 1G downward.
They don't have GPS or even ground/ocean-bouncing radar to give them altitude info?
GPS altitude should have been available if selected. Radio altimeter has a very limited range (normally displayed below 2,500 feet or so). These two and the altimeter might be about it in terms of precise altitude.
However, the altimeter should have been working anyway. There's no evidence to conclude that any of the static ports malfunctioned, or any unrelated and independent functions such as the three artificial horizons for that matter. In fact the CVR shows they were aware of their altitude when nearing 10,000 feet.
My information suggests that the sensors feeding the black box either cannot or were not made available to the primary flight instrument computers, astonishingly enough.
It would indeed be astonishing. Based on all your posts here you seem to be saying that:
- One of the ADIRUs (responsible for providing air and inertial data) gave up completely. Airspeed has nothing to do with inertial data such as attitude, and furthermore there is no reason to stop providing altitude information unless the three (3) static ports showed any differences. I think it's a pretty safe estimation based on the official BEA reports so far that the underlying inputs were not a problem there. For the ADIRU to shut off completely, solely because of lack of valid airspeed information, would be a curious vulnerability to say the least, it's not how it's designed, and again we have nothing to demonstrate this.
- Somehow the other two ADIRUs also gave up completely. See above. Alternatively you have suggested that one component (such as one of the ADIRUs) may affect another independent component. This is highly speculative and we have nothing to indicate that either.
- Somehow the ISIS (providing information such as airspeed, attitude, and altitude) failed. More speculation. It is heavily isolated - it has mechanical inputs - pneumatic lines for pitot/static, and internal components for attitude calculation - and a backup power supply.
I could note that there are some people out there who read the maintenance messages sent by the aircraft, one of them mentioning ISIS. What they don't say is that it refers solely to the display of airspeed. Similar grave errors are made in interpreting the maintenance messages and various known facts. Somewhere down the line someone saying "I don't know anything about this, but maybe X, Y and Z happened" becomes "experts know that X, Y and Z happened".
Let me say this again: if someone is saying that we know that other fundamentals than airspeed / stall warning was indicated erroneously, they are not basing it on published BEA data. Prove me wrong if you can. Everything should be in there along with some explanations, so please read the reports.
I believe the problem lies at the interface between humans and software. It appears that in this case the software ran into a situation that it cold not handle properly, and the humans were not trained to recognize this limitation. Kinda reminds me of people that trust GPS navigators blindly and end up in a river or stranded in some desert.
If con is the opposite of pro, is Congress the opposite of progress?
If it was in a stall it could very well be flying straight down while pulling up. It appears from the evidence that the tail was stalled and they were falling somewhat backwards and nose high.