Aviation stories and tips to help you stay sharp.
By Dan Sobczak
Editor's note: This content does not constitute flight instruction. Consult a certified flight instructor in your area for proper flight instruction.
You don't have to be a commercial airline pilot to learn valuable lessons from a passenger flight accident.
The Air France 447 crash into the Atlantic Ocean yields valuable lessons about how an "emotionally charged situation" can potentially make things worse in an accident chain.
Air France Flight 447 was a scheduled passenger flight from Rio de Janeiro, Brazil, to Paris, France. On June 1, 2009, the aircraft stalled and did not recover. It crashed into the Atlantic Ocean, killing all 228 passengers and crew.
The approximate flight path of Air France Flight 447. The solid red line shows the actual route. The dashed line indicates the planned route beginning with the position of the last transmission heard. Credit: Image use in the public domain. Source: Wikipedia.
In July 2012, the final report by France's Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA) -- the BEA is the French equivalent of the NTSB in the United States -- concluded that (as quoted by this Wikipedia article):
"...the aircraft crashed after temporary inconsistencies between the airspeed measurements — likely due to the aircraft's pitot tubes being obstructed by ice crystals — caused the autopilot to disconnect, after which the crew reacted incorrectly and ultimately caused the aircraft to enter an aerodynamic stall, from which it did not recover."
Reviewing accidents, such as this Air France 447 crash into the Atlantic Ocean, can yield valuable lessons learned for all pilots spanning commercial aviation and general aviation, for airplanes big and small.
With that background, let's look at Air France Flight 447's accident chain, or sequence of events, that led to this accident, which started with, and emphasizes the importance of, the pitot tube.
This particular flight had a flight crew of three: the captain, and two first officer co-pilots. This allowed for a rotation of two pilots flying while the third pilot took a break on this long 13-hour international flight across the Atlantic.
Position of the pitot probes on an Airbus A330. Source: Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA)'s final report on the Air France Flight 447 accident.
The text in the following accident chain outline contains excerpts from this Wikipedia article, which sources its information from the BEA's final report (emphasis added is our own):
The pilot warned the cabin crew that they were about to enter an area of turbulence.
About two to three minutes later, the aircraft encountered icing conditions, and ice crystals accumulated in the pitot tubes, blocking the aircraft's airspeed measurements.
The autopilot disengaged, likely due to the blocked pitot tubes. The engines' auto-thrust systems disengaged three seconds later, and the pilot flying took over control of the aircraft. Without the auto-pilot, the aircraft started to roll to the right due to turbulence, and the pilot flying reacted by deflecting his side-stick to the left.
During the next 30 seconds:
The aircraft rolled alternately left and right as the pilot flying adjusted to the altered handling characteristics of the aircraft. He abruptly pulled back on his side-stick, raising the nose, which was described as unnecessary and excessive under the circumstances.
The aircraft's stall warning sounded briefly twice due to the angle of attack tolerance being exceeded, and the aircraft's recorded airspeed dropped sharply from 274 knots to 52 knots. The aircraft's angle of attack increased, and the aircraft started to climb above its cruising level of FL350. By the time the pilot had control of the aircraft's roll, it was climbing at nearly 7,000 feet per minute.
After displaying incorrectly for half a minute, the left-side instruments recorded a sharp rise in airspeed to 223 knots. The icing event had lasted for just over a minute. The pilot continued making nose-up inputs.
The aircraft had climbed to its maximum altitude around 38,000 feet where its angle of attack was 16 degrees and the engine thrust levers were in the full forward position.
As the aircraft began to descend, the angle of attack rapidly increased toward 30 degrees. In normal flight, the aircraft's flight management computers would have acted to prevent such a high angle of attack. But in this condition, this action did not happen because the computers, having been denied reliable speed data due to the blocked pitot tubes, were no longer able to provide such protection, nor many of the other functions expected in normal flight. The wings lost lift and the aircraft stalled.
The pilot flying exclaimed "I don't have control of the airplane at all!" The co-pilot responded to this by saying, "controls to the left", and took over control of the aircraft, who pushed his side-stick forward to lower the nose and recover from the stall; however, the pilot flying was still pulling his side-stick back. The contradicting control inputs by the two pilots cancelled each other out and triggered an aural "dual input" warning.
The captain returned to the cockpit after being summoned by the first officer. By this time the angle of attack had reached 40 degrees. The aircraft had descended to 35,000 feet. The stall warnings stopped, as all airspeed indications were now considered invalid by the aircraft's computer due to the high angle of attack. The aircraft had its nose above the horizon but was descending steeply.
The pilot flying decreased the aircraft's pitch slightly, airspeed indications became valid, and the stall warning sounded again; it then sounded intermittently for the remaining duration of the flight. The angle of attack never dropped below 35 degrees for the remainder of the flight.
The first officer told the captain that "We've lost all control of the aeroplane, we don’t understand anything, we’ve tried everything". Soon after this, the first officer said to himself, "climb" four consecutive times. The pilot flying heard this and replied, "But I've been at maximum nose-up for a while!" When the captain heard this, he realized the pilot flying was causing the stall, and shouted, "No no no, don't climb! No No No!"
When the first officer heard this, he told the pilot flying to give the control of the airplane to him. The co-pilot pushed his side stick forward to try to regain lift for the airplane to climb out of the stall, but it was now too late to recover from the stall. The ground proximity warning system sounded an alarm.
The flight data recordings stopped three hours 45 minutes after takeoff when the aircraft's ground speed was 107 knots, and it was descending at 10,912 feet per minute. The aircraft remained stalled during its entire 3-minute, 30-second descent from 38,000 feet. All 228 passengers and crew on board died on impact. The aircraft was destroyed.
Three years later in July 2012, France's Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA) released its final report on the accident.
According to the BEA's report, the accident resulted from the following chain of events:
- "Temporary inconsistency between the airspeed measurements, likely following the obstruction of the Pitot probes by ice crystals that, in particular, caused the autopilot disconnection and the reconfiguration to alternate law;
- Inappropriate control inputs [performed by the crew] that destabilized the flight path;
- The lack of any link by the crew between the loss of indicated speeds called out and the appropriate procedure;
- The late identification by the Pilot Not Flying of the deviation from the flight path and the insufficient correction applied by the Pilot Flying;
- The crew not identifying the approach to stall, their lack of immediate response and the exit from the flight envelope;
- The crew’s failure to diagnose the stall situation and consequently a lack of inputs that would have made it possible to recover from it."
Ultimately, this accident came down to the following pilot-related links in Air France Flight 447's accident chain, which we've quoted here from this Wikipedia article, which sources its information from the BEA's final report (emphasis added is our own):
- "The crew lacked practical training in manually handling the aircraft both at high altitude and in the event of anomalies of speed indication;
- The two co-pilots' task sharing was weakened both by incomprehension of the situation at the time of autopilot disconnection, and by poor management of the "startle effect", leaving them in an emotionally charged situation;
- The cockpit lacked a clear display of the inconsistencies in airspeed readings identified by the flight computers;
- The crew did not respond to the stall warning, whether due to a failure to identify the aural warning, to the transience of the stall warnings that could have been considered spurious, to the absence of any visual information that could confirm that the aircraft was approaching stall after losing the characteristic speeds, to confusing stall-related buffet for overspeed-related buffet, to the indications by the Flight Director [onboard computer] that might have confirmed the crew's mistaken view of their actions, or to difficulty in identifying and understanding the implications of the switch to alternate law, which does not protect the angle of attack."
There are three important pilot-related take-aways here that pilots of all airplanes big and small can apply in their own flying:
Regarding that "emotionally charged situation", the BEA final report itself makes these two important comments:
"The amplitude of the actions may doubtless be explained by the highly charged emotional factors generated by the unexpected autopilot disconnection in the context of the flight...
"Poor management of the startle effect that generated a highly charged emotional factor for the two copilots..."
Considering how the human brain has a tendency to "shut down" in some people during stressful situations, it is possible to surmise that perhaps the Air France 447 pilots being "in an emotionally charged situation" could have been the biggest link in this accident chain.
If that "emotionally charged situation" were diffused early on, it could have broken Air France Flight 447's accident chain and allowed the flight to arrive at its destination safely.
This is why we end every blog post with the admonition to "Stay sharp!".
Because in a stressful situation, you need to remain cool, calm, and collected, just like Neil Armstrong did on Gemini 8.
On a final note, a CBS News report on Air France Flight 447 was produced in response to the release of the final report on the crash, where Captain Chesley "Sully" Sullenberger provided his comments regarding possible underlying conditions with the aircraft cockpit design itself that -- in addition to the pilot-related factors that occurred -- may have also contributed to the Air France Flight 447 accident.
Watch this CBS News report on Air France Flight 447 from Captain Chesley "Sully" Sullenberger's YouTube channel. Source: Captain Chesley Sullenberger YouTube channel; and CBS News.
The Flight Chain App team
Dan Sobczak is the founder of www.FlightChainApp.com, a mobile app that helps pilots learn from accident chains by making NTSB reports more convenient and easier to digest. Dan received his private pilot certificate in 2003.
Flight Chain App and its companion blog www.AheadOfThePowerCurve.com are committed to reducing general aviation accidents, helping improve aviation safety, and growing the pilot population.
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Flight Chain App and its blog Ahead of the Power Curve are committed to reducing general aviation accidents, helping improve aviation safety, and growing the pilot population.