Flight data from AF447 crash

[CCIP]

So, the investigators have released a statement about what they found on the flight recorders of Air France 447 that they pulled out from the bottom of the sea. You can find the full statement here:

http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.en.pdf

What do you make of it?

Sounds like a classic crash scenario - a bad combination of several factors conspiring against the plane. Bad weather + failing airspeed readings + erroneous pilot responses based on that readings = unrecoverable stall. :hmmm:

[Torplexed]

Sounds like two pilots overwhelmed by all the bells and whistles in the modern cockpit. In the last two decades we've moved toward having computers flying the jet, with pilots at the receiving end of electronic commands rather than the other way around.

US Airways Captain Sullenberger III, who flew an Airbus A320 in his "miracle" Hudson River landing two years ago, said in an interview that automation is a "mixed blessing." While computerized planes are capable of protecting a pilot, they can also produce other types of errors that would likely not have occurred in an older jet.

[AVGWarhawk]

Sullenberger's landing imo was not a miracle. The landing was accomplished by capable hands and one who understands the dynamics of his aircraft. :up:

Having some trouble downloading the PDF. :oops:

[GoldenRivet]

Having some trouble downloading the PDF. :oops:

ditto, it freezes up.

my opinion for whatever it's worth.

Supercooled water rapidly froze and overwhelmed the pitot static heating elements for a long enough period of time to cause this disaster.

this caused an autopilot disconnect, and numerous bells and whistles. chances are the pilots became completely overwhelmed by the sudden influx of data.

the NOVA series on this accident >>> http://www.amazon.com/Nova-Crash-Flight-447-n/dp/B003WKQ450 <<< i think has the cause completely nailed down, and certainly makes its case well.

[CCIP]

Sullenberger's landing imo was not a miracle. The landing was accomplished by capable hands and one who understands the dynamics of his aircraft. :up:


Also, at least from what I'd read/seen, actually Airbus automation deserves some credit in that landing as well. The stall protection system had actually helped to fly the aircraft into the water at minimum possible speed/maximum safe angle of attack without stalling, something that would be much more difficult to do purely by hand. It left the pilots much better able to concentrate on making crucial decisions at hand, without getting swamped by details.

[Herr-Berbunch]

Accident to the Airbus A330-203
flight AF 447 on 1st June 2009
Update on Investigation
www.bea.aero
27 May 2011
SPECIAL FOREWORD TO ENGLISH NOTE
This note has been translated and published by the BEA to make its reading easier for Englishspeaking
people. As accurate as the translation may be, the original text in French should be
considered as the work of reference.
History of Flight
On Sunday 31 May 2009, the Airbus A330-203 registered F-GZCP operated by Air France was
programmed to perform scheduled flight AF447 between Rio de Janeiro Galeão and Paris
Charles de Gaulle. Twelve crew members (3 flight crew, 9 cabin crew) and 216 passengers
were on board. Departure was planned for 22 h 00(1).
At around 22 h 10, the crew was cleared to start the engines and to leave the parking space.
Take-off took place at 22 h 29. The Captain was PNF, one of the co-pilots was PF.
The take-off weight was 232.8 t (for a MTOW of 233t), including 70.4 t of fuel.
At 1 h 35 min 15 ---61580;, the crew informed the ATLANTICO controller that they had passed the
INTOL point then announced the following estimated times: SALPU at 1 h 48 then ORARO at
2 h 00. They also transmitted the SELCAL code and a test was undertaken successfully.
At 1 h 35 min 46, the controller asked the crew to maintain FL350 and to give their estimated
time at TASIL.
At 1 h 55, the Captain woke the second co-pilot and said "[…] he’s going to take my place".
Between 1 h 59 min 32 and 2 h 01 min 46 ---61581;, the Captain attended the briefing between the
two co-pilots, during which the PF said, in particular "the little bit of turbulence that you just saw
[…] we should find the same ahead […] we’re in the cloud layer unfortunately we can’t climb much
for the moment because the temperature is falling more slowly than forecast" and that "the logon
with Dakar failed". The Captain left the cockpit.
The airplane approached the ORARO point. It was flying at flight level 350 and at Mach 0.82
and the pitch attitude was about 2.5 degrees. The weight and balance of the airplane were
around 205 tonnes and 29% respectively. Autopilot 2 and auto-thrust were engaged.
At 2 h 06 min 04, the PF called the cabin crew, telling them that "in two minutes we should enter
an area where it’ll move about a bit more than at the moment, you should watch out" and he
added "I’ll call you back as soon as we’re out of it".
(1)All times
are UTC.
At 2 h 08 min 07 ---61582;, the PNF said "you can maybe go a little to the left […]". The airplane began a
slight turn to the left, the change in relation to the initial route being about 12 degrees. The level
of turbulence increased slightly and the crew decided to reduce the speed to about Mach 0.8.
From 2 h 10 min 05 ---61583;, the autopilot then auto-thrust disengaged and the PF said "I have the
controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall
warning sounded twice in a row. The recorded parameters show a sharp fall from about 275 kt
to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments
later in the speed displayed on the integrated standby instrument system (ISIS).
Note 1: Only the speeds displayed on the left PFD and the ISIS are recorded on the FDR; the speed
displayed on the right side is not recorded.
Note 2: Autopilot and auto-thrust remained disengaged for the rest of the flight.
At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]".
Note 1: The angle of attack is the angle between the airflow and longitudinal axis of the airplane.
This information is not presented to pilots.
Note 2 : In alternate or direct law, the angle-of-attack protections are no longer available but a
stall warning is triggered when the greatest of the valid angle-of-attack values exceeds a certain
threshold.
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 ---61584;, 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.
Around fifteen seconds later, the speed displayed on the ISIS increased sharply towards 185 kt;
it was then consistent with the other recorded speed. The PF continued to make nose-up
inputs. The airplane’s altitude reached its maximum of about 38,000 ft, its pitch attitude and
angle of attack being 16 degrees.
Note: The inconsistency between the speeds displayed on the left side and on the ISIS lasted a little less
than one minute.
At around 2 h 11 min 40 ---61585;, the Captain re-entered the cockpit. During the following seconds,
all of the recorded speeds became invalid and the stall warning stopped.
Note: When the measured speeds are below 60 kt, the measured angle of attack values are considered
invalid and are not taken into account by the systems. When they are below 30 kt, the speed values
themselves are considered invalid.
The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the vertical
speed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degrees
and the engines’ N1’s were close to 100%. The airplane was subject to roll oscillations that
sometimes reached 40 degrees. The PF made an input on the sidestick to the left and nose-up
stops, which lasted about 30 seconds.
At 2 h 12 min 02, the PF said "I don’t have any more indications", and the PNF said "we have
no valid indications". 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. In
the following moments, the angle of attack decreased, the speeds became valid again and the
stall warning sounded again.
At 2 h 13 min 32, the PF said "we’re going to arrive at level one hundred". About fifteen seconds
later, simultaneous inputs by both pilots on the sidesticks were recorded and the PF said "go
ahead you have the controls".
The angle of attack, when it was valid, always remained above 35 degrees.
The recordings stopped at 2 h 14 min 28. The last recorded values were a vertical speed of
-10,912 ft/min, a ground speed of 107 kt, pitch attitude of 16.2 degrees nose-up, roll angle of
5.3 degrees left and a magnetic heading of 270 degrees.
New findings
At this stage of the investigation, as an addition to the BEA interim reports of 2 July and 17
December 2009, the following new facts have been established:
---136;. The composition of the crew was in accordance with the operator’s procedures.
---136;. At the time of the event, the weight and balance of the airplane were within the operational
limits.
---136;. At the time of the event, the two co-pilots were seated in the cockpit and the Captain was
resting. The latter returned to the cockpit about 1 min 30 after the disengagement of the
autopilot.
---136;. There was an inconsistency between the speeds displayed on the left side and the integrated
standby instrument system (ISIS). This lasted for less than one minute.
---136;. After the autopilot disengagement:
---132;.the airplane climbed to 38,000 ft,
---132;.the stall warning was triggered and the airplane stalled,
---132;.the inputs made by the PF were mainly nose-up,
---132;.the descent lasted 3 min 30, during which the airplane remained stalled. The angle of
attack increased and remained above 35 degrees,
---132;.the engines were operating and always responded to crew commands.
---136;. The last recorded values were a pitch attitude of 16.2 degrees nose-up, a roll angle of
5.3 degrees left and a vertical speed of -10,912 ft/min.

http://farm3.static.flickr.com/2199/5764500627_6f001be3ca_b.jpg

Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile
Zone Sud - Bâtiment 153 - 200 rue de Paris - Aéroport du Bourget - 93352 Le Bourget Cedex FRANCE
T. : +33 1 49 92 72 00 - F : +33 1 49 92 72 03
www.bea.aero

[CCIP]

Yeah, the nose-up inputs is what I referred to as the apparent erroneous response to the situation. Sounds like in the end, it was the PF's input which stalled the plane. Probably caused by massive disorientation, of course.

By the way, for those of you familiar with Airbus systems, what would've caused the plane's controls to go into Direct Law? Would that be the loss of airspeed readings?

[AVGWarhawk]

Also, at least from what I'd read/seen, actually Airbus automation deserves some credit in that landing as well. The stall protection system had actually helped to fly the aircraft into the water at minimum possible speed/maximum safe angle of attack without stalling, something that would be much more difficult to do purely by hand. It left the pilots much better able to concentrate on making crucial decisions at hand, without getting swamped by details.

But again, I refer back to the pilot knowing his aircraft. Scully worked with the aircraft and what the aircraft electronics can perform/capable of doing. I still stand by my capable hands statement but would like to add cool head in this situation. :up:

[CCIP]

Oh, by all means. Would never take the credit away from the pilot - in the end, it's his decisions and skills that saved the day, the plane only helped a little :up:

[AVGWarhawk]

Oh, by all means. Would never take the credit away from the pilot - in the end, it's his decisions and skills that saved the day, the plane only helped a little :up:

What is interesting and a good question, do pilots get completely dependent on the aircraft electronics to the point of not being able to handle a situation such as this Air France disaster? In other words, do they become complacent in the routine? I understand most airline companies test and retest pilots. Training is ongoing. :hmmm:

[MH]

Looks similar to this disaster?
http://www.youtube.com/watch?v=-kHa3WNerjU

[CCIP]

Looks similar to this disaster?
http://www.youtube.com/watch?v=-kHa3WNerjU

Actually this one's the completely opposite. In this old scenario, it appears that the stall protection system worked TOO well, and decided that it knew better than the pilot what the airplane was doing, pitching down to increase airspeed and maintain altitude when the pilot input was to try and pull the plane up. Although the pilot did perform the maneuver without adequate preparation and with too low a safety margin.

On the surface, this AF disaster looks like the opposite - the instruments and stall protections failed completely, the airplane's systems had nothing to offer the pilot, and the pilot got confused and flew the airplane into a stall by pitching up - and the plane did exactly what the pilot asked it to do.

[AVGWarhawk]

Not really, no. :hmmm:

[Jimbuna]

What is interesting and a good question, do pilots get completely dependent on the aircraft electronics to the point of not being able to handle a situation such as this Air France disaster? In other words, do they become complacent in the routine? I understand most airline companies test and retest pilots. Training is ongoing. :hmmm:

That's an excellent question actually and one I doubt an airline would want to answer for fear of future claims against it.

Personally, I think it should be a mix of the two but the pilot should always have the ability to override the electronics should he feel it necessary.

[mako88sb]

There's been a ongoing discussion of this incident since it happened over at Airdisaster.com;

http://forums.jetphotos.net/showthread.php?t=49818

[AVGWarhawk]

Personally, I think it should be a mix of the two but the pilot should always have the ability to override the electronics should he feel it necessary.

I agree, however, the pilot should be trained to understand the function of electronic assist as CCIP points out. In Skully's case, allowing his physical input work with the electronic input to safely land the craft. Knowing whether to pull the plug on the electronics or work in unison.

[Anthony W.]

The idea of "Stall Warning" indicated by the computer, and "Nose Up" inputs by the pilot go contradictory to me. Isn't there a video of a Panther landing on a carrier when he gets a stall warning, pitches up, rolls over, and smashes into the deck nose first?

[flatsixes]

I'm no pilot, but just playing flight sims you learn quickly how (and how not) to recover from a stall. It seems incredible to me that any driver capable of piloting an Airbus from one continent to another could possible forget something so basic. And it is not as though he didn't have enough altitude to have time to correct. The data are there, I know, but it's just so... odd that I'm having a tough time believing that's there's nothing else to it.

Gremlins, perhaps.

[magic452]

I remember reading a NTSB report in Aviation Week of a very similar incident.
It was an intercontinental flight B707? about 40 years ago.

The pitot tubes froze and gave the pilot higher air speed readings than he really had, he reduced power and increased angle of attack to bring down the air speed. Of course the plane stalled but he had enough altitude to recover and save the plane. He lost about 25,000 of the 30,000+ feet he had.
At the lower altitude the tubes unfroze giving a good air speed.
NTSB criticized the pilot for not using other interments to check the believability of his air speed as I remember.

Not so many computer aids back in those days may have worked in his favor?

Magic

[Stealhead]

Regardless of the technology available in a given aircraft it is the pilots responsibility to know when his instruments may be giving him incorrect data they got confused but
that can happen even to the most skilled pilot or aircrew.I think they got over whelmed trying to correct the situation they where in and failed to realize the pitot tubes had frozen.

One reason why studying each aircraft disaster is so important. There was an DC10 crash American Airlines Flight 191 back in the 70s where one of the engine nacelles fell off during take off and as a result of several things failing the crew was unable to know that because of the damage suffered the normal procedure for the situation they where in was wrong and they crashed.Based on the data that they had the pilots followed the correct procedure because they did not know that the shaker stick was not going to work this wiki article tells it better: http://en.wikipedia.org/wiki/American_Airlines_Flight_191

more on 191: http://aviation-safety.net/database/record.php?id=19790525-2

[MH]

At 2 h 12 min 02, the PF said "I don---8217;t have any more indications", and the PNF said "we have
no valid indications". At that moment, the thrust levers were in the IDLE detent and the
engines---8217; N1---8217;s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. In
the following moments, the angle of attack decreased, the speeds became valid again and the
stall warning sounded again.

Here it seems is the clue why pilots might be pulling on the stick.
The computer disregards info when speed is below valid value shutting down all stall warnings.
It looks like the pilots passed threshold point for the on-board systems and the computer confused them.
The computer warning caused the pilots to keep the plane in stall situation.
Possibly a situation that software designers thought could never happen?

[mako88sb]

Regardless of the technology available in a given aircraft it is the pilots responsibility to know when his instruments may be giving him incorrect data they got confused but
that can happen even to the most skilled pilot or aircrew.I think they got over whelmed trying to correct the situation they where in and failed to realize the pitot tubes had frozen.


From what I've read so far, it's more like they acted incorrectly after realizing they had a problem with ice blocking the pitot tube. Here's a summary from a member over at airdisaster.com:


Quote:
"Originally Posted by Myndee
Also, could someone kindly post a summary of what happened in laymens terms for those of us who do not 100% understand all of the lingo. Thanks.


- The pitot tubes were blocked or otherwise rendered ineffective.
- That triggered an unreliable speed event.
- The crew correctly identified the unreliable speed event and the fact that the autopilot and autothrottle had disconnected.
- A pilot took manual control of the plane.
- He should have applied the memory items for unreliable speed: Point the nose 5º above the horizon and set the throttles to climb thrust.
- Instead, he didn't set climb thrust and pointed the nose more than 10º above the horizon.
- The plane climbed, lost speed, and stalled.
- The pilot never recovered from the stall because he didn't apply the correct control inputs, as you know by now, so the plane kept falling stalled for 38,000ft and three minutes.

I think that that very much summarizes it. Gabriel"



"Originally Posted by Harding
What is this "memory items"? At first i thought it was a emergency checklist of some kind - but i changed my mind after reading the report. Seems like they actually didnt know they where in an emergency for quite a while?"


"No. They correctly noticed the unreliable speed at once.

There is a two-fold procedure for an unreliable speed event:

1- Fly the plane at a given initial pitch and thrust that ensures that the plane remains safe. This are the memory items because you have to know them by heart. There's no time to go grab the book and look up for the correct procedure.
2- Now, with the plane stabilized as said above, one pilot keep flying the plane according to these two memoty item values, and the other calmly grabs the book, looks up for unreliable speed, and with a few parameters (aircraft weight, altitude and temp) look up in a table for fine tunned values of pitch and thrust that not only will ensure safety but also will keep the altitude. Gabriel"



"The pilots were obviously not well trained for this. They failed to perform the two basic memory items. I think they might also have ignored the stall warnings because they knew the airspeed was erroneously low and considered this the cause of false stall warnings. However, the QRH specifies that pilots are to RESPECT STALL WARNINGS and to ignore any ECAM message warning them of RISK OF UNDUE STALL WARNING.

I'm also wondering if the altimeters and VSI could have been affected. The FPV was lost during the sequence. The FDR has them at 40° AoA and -10,000 ft/min V/S, but only 15° pitch with 100% N1 thrust. How is that possible? Did they reduce thrust at FL380 to remain in the envelope and let it fall, and then firewall it as they were falling out? This is not explained in the briefing. Or is it possible that the pitch indications were erroneous, both on the PFD and on the FDR? And why did they subsequently bring thrust back to IDLE in a developed stall, when airspeed was obviously needed? Did the PF do this or the Capt?

The best I can make of this is that thrust lock, a bit of load factor and pitch input caused an initial stall warning and an excessive rate of climb. They momentarily recovered by reducing pitch but the thrust setting remained too low and the pitch trim raised the AoA once again. With the second stall warning they initially applied TOGA thrust and pitch in excess of 10° This resulted in an excessive rate of climb until they reached their maximum FL380. Then it would seem that to reduce the V/S, they reduced thrust too aggressively while not reducing pitch and stalled, and then returned thrust to TOGA after the stall had developed, too late to prevent it, and then reduced again to IDLE fearing overspeed at at high rate of descent (apparently unaware of their pitch or AoA). That's the best I can make of it.

I am not surprised to hear that the pilots did not do the memory items correctly. That seems to be what killed them. Obviously, there was an industrywide training deficiency on this issue, and perhaps a deficient set of procedures issued by Airbus. The threat was obviously underrated, since ice-related pitot failure is not supposed to be happening at FL350, based on conventional wisdom at the time, and doesn't seem to occur outside the ITCZ. But it had been happening and both Airbus and the operators were aware that a threat existed. Neither seem to have reacted properly with training and procedures.

But I can't accept that such an experienced crew would not be well versed on general stall avoidance and recovery procedure either. They must have been deprived of vital positional awareness beyond airspeed data to get into the mess described in the report.

Or perhaps we still have a lot more to learn about human factors. I hope we will see the FDR plots and get a CVR translation soon. There are too many new questions in my head. Evan"

[Torplexed]

Regardless of the technology available in a given aircraft it is the pilots responsibility to know when his instruments may be giving him incorrect data they got confused but
that can happen even to the most skilled pilot or aircrew.I think they got over whelmed trying to correct the situation they where in and failed to realize the pitot tubes had frozen.

One reason why studying each aircraft disaster is so important. There was an DC10 crash American Airlines Flight 191 back in the 70s where one of the engine nacelles fell off during take off and as a result of several things failing the crew was unable to know that because of the damage suffered the normal procedure for the situation they where in was wrong and they crashed.Based on the data that they had the pilots followed the correct procedure because they did not know that the shaker stick was not going to work this wiki article tells it better: http://en.wikipedia.org/wiki/American_Airlines_Flight_191

more on 191: http://aviation-safety.net/database/record.php?id=19790525-2

I remember that accident. It pretty much destroyed the future sales of the DC-10. That heart-stopping photograph on the front page of every newspaper in particular. We take pictures and video of disasters for granted nowadays, but having the presence of mind to grab your camera and snap off a quick picture then was rare.

http://upload.wikimedia.org/wikipedia/en/thumb/5/53/Aa191_ohare.jpg/260px-Aa191_ohare.jpg

[sharkbit]

DC-10's were great airplanes with a bad rap. I bet if you look at the accident rate per number of flight hours, they would probably be about average.

Here's one quick link that might back that up:

http://www.boeing.com/news/techissues/pdf/statsum.pdf

A quick glance at page 21 may show that.

:)