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Bloomberg on AF447

densoo

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Air France Probe Shows Plane Stalled in 3.5-Minute Near Freefall
By Laurence Frost and Andrea Rothman - May 27, 2011
Air France Flight 447 crashed after the Airbus A330 lost speed and stalled before beginning a three- and-a-half minute plunge into the Atlantic Ocean that killed all 228 people on board, an investigation found.

The findings by the French BEA air-accident investigation bureau show the autopilot disengaged shortly after the pilots had alerted cabin crew of possible turbulence ahead. According to data from the flight recorders, the younger of the two men angled the jet’s nose higher, a position the aircraft maintained until its final impact.

The preliminary report sheds more light on the final minutes before the deadliest crash in Air France’s history, with the pilots scrambling to avert disaster as the jet hurtled toward the ocean surface at a speed of 180 feet (55 meters) a second. The data shows that the junior crew member, who was 32 and the least experienced of the three, was piloting the aircraft until less than one minute before the actual crash.

“The question is why the pilot kept giving nose-up inputs when the plane was in a stall,” said Paul Hayes, director of safety at Ascend Worldwide Ltd., a London-based aviation consultant company. “You should put the nose down to recover speed, and away you go.”

Breakthrough Recovery

The investigation achieved a breakthrough after the two flight recorders were recovered from 3,900 meters (12,800 feet) beneath the Atlantic and returned to Paris this month, two years after the jet disappeared into the night on June 1, 2009. All data and voice recordings from the two recorders were recovered in full, after being submersed for two years, the BEA said.

A low-speed stall occurs when an aircraft slows to the point where its wings suddenly lose lift, an incident pilots are trained to overcome. Earlier transmits from the jet had already shown that airspeed sensors, or pitot tubes, made by Thales SA (HO) had failed, presenting pilots with a sharp drop in speed readings on their displays after they entered ice clouds.

The analysis shows that the pilots had favored to climb above the approaching stormy clouds but were prevented from doing so because it wasn’t cold enough for the jet to ascend to that level. The crew alerted flight attendants that they should “watch out” as the approaching zone would move the jet around.

Resting Pilot

With the flight captain resting and the two co-pilots at the controls, the auto-pilots disengaged four hours into the flight. The pilots acknowledged that the speed sensors had failed as they responded by pulling up the nose of the aircraft, voice and data recordings show. A stall warning sounded in the cockpit, the BEA said.

According to the BEA, the co-pilots continued to increase the angle of climb, rising rapidly from 35,000 feet to 37,500 feet. When a third stall warning sounded, they continued to pull back on the controls with the engines set to full thrust and rose to about 38,000 feet, where the plane entered a stall.

Less than two minutes after the autopilot went offline, the chief pilot, Marc Dubois, returned to the cockpit, and the conversation shows he was with his colleagues during the remainder of the flight. It’s routine for pilots to take a break away from the cockpit on long-haul flights, Air France has said.

Last-Minute Control

Dubois never actually took back either his seat or the controls, according to the report. Dubois, 58, had almost 11,000 hours of flight experience, compared with fewer than 3,000 hours for the youngest member of the cockpit. The third member of the crew, 37, was given control in the last minute before impact.

Air France said the made a detour to avoid bad weather, and that the pilots showed professionalism, according to an e-mailed statement by the French airline.

With the plane’s nose still pointed up about 15 degrees, the jet began falling at about 10,000 feet a minute, rolling left and right. Almost one minute into the stall, the pilots had reduced engine thrust and tried pushing down on the controls to lower the nose.

Airspeed indications returned and the alarm sounded again as the stalled aircraft picked up some speed, though the plane continued falling until the first co-pilot commented that the aircraft was approaching an altitude of 10,000 feet. The final recordings show the aircraft had fallen back to a speed of about 123 miles per hour (198 kilometers per hour), the BEA said.

‘Technical Observations’

The BEA said its preliminary findings from the black-box data have not yet established any conclusions about the accident’s causes or led to any recommendations. An interim report is due in mid-July. Airbus, the world’s largest manufacturer of civil aircraft, said last week that it had no additional recommendations to operators of the A330 aircraft.

“What we’re publishing today are technical observations, including actions by the crew, which don’t explain the accident,” BEA chief Jean-Paul Troadec told reporters. “Understanding this chain of events and the reasons behind the crew’s actions is a complex task that is just beginning.”

The report concluded that the aircraft remained stalled during its descent, and that the engines were operational and responded to crew commands throughout. Dubois was among the victims recovered from the ocean’s surface in the weeks after the crash, along with debris that included most of the tail fin.

To contact the reporters on this story: Laurence Frost in Paris at lfrost4@bloomberg.net; Andrea Rothman in Paris at aerothman@bloomberg.net

To contact the editor responsible for this story: Benedikt Kammel at bkammel@bloomberg.net
 

eaglesview

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Yep, 98% pilot error.

I hope that's sarcasm. Nobody will actually know what was going on. First when is the last time the press got anything correct and secondly there could always have been secondary influences that were driving their decision process. Only the classless make assumptions about the dead. Let's see how many are here on FI.
 

Wesb737fo

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Dang. I agree with Eagle on the point about the press not presenting all the details. At this point it is clear that the pilot's attempt to climb over the weather resulted in a stall, but, the question remains why weren't they able to recover from it. It will be interesting to see the second by second account of the events. At what point did they get their A/S indication back and did they believe it was reliable. The A/C remained stalled all the way down. 123 mph final recorded speed. why? More questions to be answered.
 

densoo

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Dang. I agree with Eagle on the point about the press not presenting all the details. At this point it is clear that the pilot's attempt to climb over the weather resulted in a stall, but, the question remains why weren't they able to recover from it.
11,000 hours for CA? 3,000 hours for the "copilot" at the controls? Wow. The average FO at a major likely has more than 11,000 hours. Quality time is good, but quantity also has it's place.
 
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Dash Power

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Earlier transmits from the jet had already shown that airspeed sensors, or pitot tubes, made by Thales SA (HO) had failed, presenting pilots with a sharp drop in speed readings on their displays after they entered ice clouds.

This would be confusing for any pilot no matter what their experience. But I agree that there is much more that needs to be known before any judgement is passed.
 

densoo

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This would be confusing for any pilot no matter what their experience. But I agree that there is much more that needs to be known before any judgement is passed.
I would agree. At night, in a thunderstorm cell, with no airspeed indicators, it could be tough to figure out exactly what you need to do. I wonder if there were any emer/ backup speed indicators at all.
 

Wesb737fo

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Anybody remember the accident in South America a while back. Air Peru crashed because the static ports were covered while the a/c was cleaned and never removed. The flight crew had multiple warnings, no reliable a/s or altimetry info. at night over the water. Couldn't figure out if they were stalling or overspeeding.
 

LJ45

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we need to teach "pitch+power+configuration=performance"

As a professional pilot you should be able to fly your aircraft without airspeed. This was taught to me in basic training.
 

Mach92

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we need to teach "pitch+power+configuration=performance"

As a professional pilot you should be able to fly your aircraft without airspeed. This was taught to me in basic training.

It was at night, over water, heavy T-storms, probably getting the sh!t beat out of them. I read somewhere that the flight plan was at max range. This explains why they did not take the route a LH 747-400 that departed some 30 minutes before they did. That flight plan was west and north to stay clear of the weather. Just a lot of bad choices before they left the gate.
 

LJ45

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It was at night, over water, heavy T-storms, probably getting the sh!t beat out of them. I read somewhere that the flight plan was at max range. This explains why they did not take the route a LH 747-400 that departed some 30 minutes before they did. That flight plan was west and north to stay clear of the weather. Just a lot of bad choices before they left the gate.

I agree, but at some point you still have to fly your aircraft when the $hit hits the fan. We are starting to see a pattern in these accidents of lack of basic stick and rudder skills.
 

satpak77

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we need to teach "pitch+power+configuration=performance"

As a professional pilot you should be able to fly your aircraft without airspeed. This was taught to me in basic training.

absolutely 100% agree.
 

DeucesWild

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The report says nothing about entering a thunderstorm. After the loss of airspeed indication, they did not maintain proper pitch and power setting, and the aircraft stalled. They applied 'pitch up' control in response to the stall and maintained 'pitch up' control throughout most of the descent.
 

flyburg

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I dunno know, but to maintain proper pitch and power setting during severe turbulence is pretty difficult!!! Even worse proper pitch and power during severe turbulence could be wrong as well, a stalled airplane could have the right pitch attitude and power and still be stalled, without angle of attack indicator and proper speed indication it would be hard to surmise.

Hindsight is easy, but it took 3 minutes for this aircraft to crash.

To say they didn't fly into the TS! Everybody knows that severe turbulence can also be encountered away from the TS.

Just recently had upset recovery training on the 74 as part of initial qual. With 15 degrees of nose down and full power, just pulling a bit too much would induce a stall at high altitude, how's that for proper pitch and power, try that at night with no valid airspeed indication!!!
 
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LJ45

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Just recently had upset recovery training on the 74 as part of initial qual. With 15 degrees of nose down and full power, just pulling a bit too much would induce a stall at high altitude, how's that for proper pitch and power, try that at night with no valid airspeed indication!!!

You just proved you know the proper way to recover from a high altitude stall and the pitch and power needed for your aircraft. So now that you had this training, if you stall you will not stay pitched up? You are making our point even clearer.
 

LJ45

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I dunno know, but to maintain proper pitch and power setting during severe turbulence is pretty difficult!!!QUOTE]


Hold pitch and power for turb penatration and don't chase airspeed and altitude.
 

CesnaCaptn

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Airbus pilots-will a blocked pitot tube result in the airspeed tapes disappearing or Xed out, or would the tapes act like the airspeed indicator would on a C-172 with a blocked pitot tube, i.e. like an altimeter? Maybe the pilots were trying to get their airspeed "under control" by pitching back.
 
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