Air France: Crash Report Shows Confused Cockpit

[AntZ]

Crash Report Shows Confused Cockpit


By ANDY PASZTOR And DANIEL MICHAELS

MAY 27, 2011, 10:33 A.M. ET




Reacting to wildly fluctuating airspeed indications and apparently confused by repeated stall warnings, pilots of an Air France jetliner in 2009 continued to pull the nose up sharply—contrary to standard procedure—even as the Airbus A330 plummeted toward the Atlantic Ocean, according to information released Friday by French accident investigators.

The long-awaited factual report, though it doesn't include any formal conclusions about the cause of the June 2009 crash that killed 228 people, provides details about a prolonged stall that lasted more than three and a half minutes. Throughout the descent, according to the report, "inputs made by the [pilot flying] were mainly nose-up" and the "angle of attack," or the position of the longitudinal axis of the plane in relation to the airflow "remained above 35 degrees."


If an airplane has entered an aerodynamic stall, which means its wings have lost necessary lift to remain airborne, from their earliest training pilots are taught to immediately push the nose down to regain speed, lift and maneuverability

The report also paints a somewhat unflattering picture of a seemingly confused cockpit, with the crew making extreme inputs to their flight controls and the engines spooling up to full power and later the thrust levers being pulled back to idle. At one point, according to the report, both pilots sitting in front of the controls tried to put in simultaneous commands.

The senior captain of the flight, who was on a routine rest break in the cabin when the trouble started, rushed back to the cockpit and was present during a large portion of the descent.

Air France praised the three pilots, who "demonstrated a totally professional attitude and were committed to carrying out their task to the very end," the airline said in a statement.

The carrier, a unit of Air France-KLM SA, noted that "the initial problem was the failure of the speed probes which led to the disconnection of the autopilot and the loss of the associated piloting protection systems."

The model of speed probes on the Air France plane, and others like it, had a history of icing up and giving faulty readings. Airbus and regulators had established procedures to handle such situations with the probes, which are called pitot tubes. These procedures focused on maintaining sufficient thrust and avoiding extreme maneuvers.

Comments by the crew, cited in the report published Friday, indicate that the crew knew they had problems with their speed readings. But pilots' actions, as presented in the report, were apparently not consistent with the prescribed reaction to the situation.

Airbus, a unit of European Aeronautics Defence & Space Co., said in a statement that it is committed to continuing to provide support to the investigation "with the objective of identifying all potential lessons to be learnt."

About two minutes after the plane's autopilot and automated thrust controls kicked off due to the airspeed-indicator problems, the pilots were manually controlling the twin-engine jet as the wings rocked from side to side, the report reveals

"I don't have any more indications," one of the pilots said, referring to airspeed. "We have no valid indications." At that moment, according to the report, the thrust levers were pulled back to idle. The report also said that both engines were operating and responding normally to pilot commands.

About a minute before impact, the report indicates "simultaneous inputs by both pilots on the sidesticks" that control the aircraft, with one of the pilots trying to clear up the confusion by telling the other "go ahead, you have the controls."

Pilots are trained to avoid such simultaneous commands.


http://online.wsj.com/article/SB10001424052702304066504576349112775425674.html

[Deepsepia]

This is an awful story, tragic, stupid, unnecessary.

From what I'm reading, the crew responded to a stall by doing the worst rookie mistake, pulling up on the stick . . . you loose lift, and never recover from the stall doing that.

Its actually a strong argument for a more automated cockpit. That three pilots, over a four minute span, couldn't figure out how to recover from a stall with a flyable aircraft is simply astonishing. There's a default "instruments are unreliable" flyable profile for these jets-- you put the plane into that profile, and it will fly, while you figure out what's gone wrong.

[RBP]

Wow, that is stunning.

[AntZ]

Its actually a strong argument for a more automated cockpit.


That's not really the answer! This is a simple case of loss of orientation, then compounded by wrong information from the same equipment that shut off the autopilot. Airbus already has removed the pilot from being able to "hurt" the aircraft. Boeing up till recently has always given the pilot the ability to be a pilot and fly out of trouble. BUT, all this is canceled out when it's black outside and the instruments themselves are deceiving you. Very very similar circumstances caused crashes with a chartered 757 in the Caribbean, another 757 off Chile when a cleaning crew covered the static ports with duct tape and forgot to remove it. There was a TACA 737 that broke up over Panama when the crew had the artificial horizons locking hard over left then snapping hard over right. The crew was frantic trying to counter what their instruments were telling them. The famous "Kid in the cockpit" Aeroflot crash in Russia was caused by a flaw in the Airbus system that allowed half the autopilot to disengage and highly experienced pilots crashed the plane because of not believing what they were seeing and loss of orientation. Again, all at night under high stress emergencies.


Honestly, I think all civil aircraft need a F.L.I.R. system (night vision). A simple lens on the nose like most all military aircraft, can give the pilots a clear view of the horizon so they can at least see the ocean and sky and settle their minds.

[Deepsepia]

That's not really the answer! This is a simple case of loss of orientation, then compounded by wrong information from the same equipment that shut off the autopilot. Airbus already has removed the pilot from being able to "hurt" the aircraft. Boeing up till recently has always given the pilot the ability to be a pilot and fly out of trouble. BUT, all this is canceled out when it's black outside and the instruments themselves are deceiving you. Very very similar circumstances caused crashes with a chartered 757 in the Caribbean, another 757 off Chile when a cleaning crew covered the static ports with duct tape and forgot to remove it. There was a TACA 737 that broke up over Panama when the crew had the artificial horizons locking hard over left then snapping hard over right. The crew was frantic trying to counter what their instruments were telling them. The famous "Kid in the cockpit" Aeroflot crash in Russia was caused by a flaw in the Airbus system that allowed half the autopilot to disengage and highly experienced pilots crashed the plane because of not believing what they were seeing and loss of orientation. Again, all at night under high stress emergencies.


Honestly, I think all civil aircraft need a F.L.I.R. system (night vision). A simple lens on the nose like most all military aircraft, can give the pilots a clear view of the horizon so they can at least see the ocean and sky and settle their minds.

You know your avionics, so I'll defer to your wisdom here. What I'd understood is that there's a high altitude stall profile, usually something like %85 thrust, 15 degrees nose up, that will fly the plane, without risk of overspeed or stall. I like your night vision solution . . . the neat thing about it is that the horizon, if visible, won't "fail" with other stuff . . . its independent, the right kind of failure fallback. Do FLIR see through weather, though? If you're in cloud, can you see horizon?

Reading about all this, its kinda amazing just how narrow the "window" of flyability is at high altitude . . . slightly too fast or too slow and bad stuff happens.

oh, and



another 757 off Chile when a cleaning crew covered the static ports with duct tape and forgot to remove it.


Holy crap.

[AntZ]

I got the country wrong, it was off Peru not Chile. :doh:

It was going to Chile.




Aeroperú Flight 603 was a scheduled flight from Jorge Chávez International Airport in Lima, Peru (SPIM), to Comodoro Arturo Merino Benítez International Airport in Santiago, Chile (SCEL), which crashed on October 2, 1996.

The pilots struggled to navigate the aircraft after the failure of all the plane's instruments. With the pilots unaware of the plane's true altitude, the plane's wing hit the water and crashed shortly afterward. The cause of the instrument failure was a maintenance worker's failure to remove tape covering the static ports necessary to provide correct instrument data to the cockpit.
Contents

Overview

On October 2, 1996, shortly after takeoff just past midnight, the Boeing 757 airliner crew discovered that their basic flight instruments were behaving erratically and reported receiving contradictory serial emergency messages from the onboard computer, such as rudder ratio, mach speed trim, overspeed, underspeed and flying too low. The crew declared an emergency and requested an immediate return to the airport.

Faced with the lack of reliable basic flight instruments, constantly receiving contradictory warnings from the aircraft's flight computer (some of which were valid and some of which were not), and continuously believing that they were at a safe altitude, pilot Eric Schreiber and copilot David Fernández decided to cautiously begin the descent for the approach to the airport. Since the flight was at night over water, no visual references could be made to convey to the pilots their true altitude or aid the pilots in the descent. Also, as a consequence of the pilot's inability to precisely monitor the aircraft's airspeed or vertical speed they experienced multiple stalls resulting in rapid loss of altitude with no corresponding change on the altimeter. While the altimeter indicated an altitude of approximately 9,700 feet, the aircraft's true altitude was in fact much lower.

The air traffic controller had a Boeing 707 take off to help guide the 757 back to land. Before the 707 could reach the 757, the 757's wingtip struck the water approximately twenty-five minutes after emergency declaration, making the pilots realize the true altitude of the airliner; The pilots struggled with the controls and managed to get airborne again for twenty seconds, but the aircraft crashed inverted into the water. All nine crew members and sixty-one passengers died. It is unclear if the pilots noticed the radar altimeter after passing through 2500 feet or not as no statement was made in the report.

After the crash recovery crews found nine bodies floating; the rest of the bodies sank with the airliner.

[Deepsepia]

I got the country wrong, it was off Peru not Chile. :doh:

It was going to Chile.

Department of WTF

Cleaning crew error + walkaround failure = 70 people dead. Shocking.

[AntZ]

Department of WTF

Cleaning crew error + walkaround failure = 70 people dead. Shocking.

This one was a case of everything that could go wrong went wrong! The cleaning supervisor was absent that day and a inexperienced person was left to do the job. There is a FAA & Boeing approved tape for the ports, that tape is bright colored, thin, and has a weak adhesive. The color can be spotted from the ground, and if missed, the weak adhesive can make it come off from the pressure changes in the ports or just the airspeed from take off. Because the cleaning crew used duct tape, the gray blended perfectly with the gray paint color scheme and was missed by the flight crew night time walk-around inspection. Then the fact that the duct tape is so damn strong, it held strong and caused the wild pressure fluctuations the computers were trying to interpret as over speed to stalls then back to over speed again.

Back to the thought about removing the possible human error from the equation, this has been the debate for years! Boeing and Airbus went in two different directions, and Airbus really shook up the aviation world with the removal of the yoke and the install of the joystick. That drove the point home that the computer IS flying the plane, the pilot is just managing the system. But if the computers get bad information from ports and Pitot tubes, then the "fail safe" system goes out the window. A clogged Pitot tube is the direct cause of the B-2 crash in Guam.

Your question about F.L.I.R., the cheapest and basic system is essentially night vision goggles. It just grabs all the available light for night vision, so clouds and fog does blind it. The far more advanced versions blends that with various radars and other advanced tools, so it cuts right through the weather. Those systems are state of the art and are standard on attack military aircraft, but are ridiculously expensive. It took over a decade for airlines just to adopt Collision Avoidance Radar because of per plane costs.

The "loss of orientation" has been a fear for pilots for over a half century, and after the Gulf War, it was recognized as a huge problem for the F-117 Stealth Fighter. Because of all night operations, there were many close calls and near crashes because of the pilots being distracted by their missions and forgetting the flight itself. They integrated an override into all systems to take full control of the aircraft and bring it to a safe and level flight no matter what was happening. So a pilot can just avoid the whole fight trying to gain control and just push a button. I don't know for sure, but most likely that software is in the ATF and JSF.

[Deepsepia]

Thanks. Stuff like this and Fukushima is instructive. When you see disasters, its often not that some critical and complex failure occurred, its that a failure occurred and someone did something really stupid.

Think of Fukushima: had they put their backup generators on the roofs of the buildings, they'd have been fine. Instead, they harden the reactors against earthquake (worked very well), and the generators get washed away.

I like your FLIR answer because its a "different kind of answer". You'd still be depending on someone to think clearly in crisis, but it would give them, an "out of the box" solution that didn't depend on anything else. I suppose you could also have an inertial guidance system, with the mass market in microsensors (eg tablet market) it need not cost a fortune to build a backup system that would give you some data (there'd be limitations -- groundspeed not airspeed). Inertial systems historically were a pain, requiring a lot of calibration, not what you want in a backup, but now they're more self contained.