EASA has just called a Loss of Control (LOC) conference in
Definitely better late than never. The Air France 447 accident suggests that no airline can consider itself free of the risk of loss of control if circumstances combine to confuse their pilots.
Meanwhile the French investigator (BEA) of the AF447 crash has shed new light on flight deck activity by publishing a transcript of flight deck conversation during the last few minutes. Tomorrow it will publish an English translation, but here is my understanding of it until they do.
The fact that AF447 crashed following a transient airspeed reading anomaly in an otherwise healthy aeroplane has always appeared to suggest the pilots failed to comprehend fully - and therefore to control - what was going on. The transcript reveals their total bewilderment about what was happening following autopilot/autothrottle disconnect.
When the captain departed the flight deck for his rest period, he did not give instructions as to the roles of the two copilots, according to the BEA. The copilot who remained in the right hand seat (RHS) took the role of pilot flying (PF) without actually making it explicit. The BEA notes that this lack of clarity about the roles of PF and pilot not flying (PNF) under these circumstances is unacceptable.
In the cruise, however, the PF was adjusting his weather radar range to identify storm clouds they would need to avoid, and discussing anti-icing precautions to apply in their vicinity. These are standard preoccupations for pilots in the inter-tropical convergence zone, and the action the pilots were taking shows they were awake despite the fact things were quiet and the time was 02:00h.
Then the speed sensor disparity, triggered by ice crystals in the pitot tubes, caused the autopilot/autothrottle to disconnect, and the calm was shattered. The control system shifted into alternate law, in which the aircraft loses its stall protection (but not stall warning). The PF said: "I have the controls."
The PF's initial reaction was to pull the stick back, putting the aircraft into a climb. Five seconds later there was a system-generated verbal warning of "stall, stall". The PF reacted with "What's that?" and the PNF replied "Stall". The PF's response was: "We haven't got a good...not a good...speed reading."
Moments later the PNF said: "We have lost the, the, the speeds then, autothrust engine lever thrust".
Meanwhile the aircraft was still climbing, the PF's stick still held back, the speed well below stalling speed, the throttles in the Climb detent, and power increasing to 100%.
The PNF then says: "We are losing...Wing anti-ice." He switched the anti-ice on, and two seconds later exclaimed - twice: "Pay attention to your speed", to which the PF replied: "Okay okay okay I will descend again," but in the next 15s or so the two pilots exchanged words indicating confusion about whether they were still climbing or had achieved descent.
But the aircraft was still, indeed, climbing, and the PF, despite temporarily relaxing the stick-back input, had resumed it.
Some 25s elapsed between the PNF warning the PF to "watch his speed" and the time that the aircraft starts to descend. But when it does, the aircraft's attitude is still between 6deg and 13deg nose-up, and at that vertical-speed reversal point the "stall, stall" warning returns, this time with the "cricket" sound as well. Five seconds later the crew moves the throttle levers from the Climb detent into TOGA (take-off/go-around) position to obtain full power.
No words are spoken by either of them for about 10s, the descent rate is increasing, and then the PNF says: "Above all avoid applying lateral [roll] control", to which the PF replies: "I'm in TOGA, eh?" and 18s later the PNF says: "We have the power, so what's going on?"
Nobody has mentioned the aircraft attitude so far. In fact no-one ever mentions it in a substantive way. The attitude is actually about 18deg nose up, which is the reason the engine power is not producing the results the crew expect to see. Vertical speed (descent) is still increasing dramatically, and the speed the pilots see is varying between 130kt and 160kt.
The PF says: "I don't have control of the aeroplane here. I have absolutely no control of the aeroplane." His stick input is on the nose-up and full-left stops. The attitude is nearly 15deg nose up and the roll angle is varying between 16deg right and 40deg right.
The PNF says: "Control to the left", and he takes control. He puts the stick fully left, then nearly full nose up. The Nos 1 and 2 angle of attack sensors have entered the "invalid" range, and the No 3 reads 33deg. The PF says: "I have the impression of high speed."
Probably slipstream noise.
At that moment the captain re-enters the flightdeck, and says: "What are you doing. What's going on? I don't know I don't know what's going on."
The stall warning sounds again, with the cricket sound.
The power levers are placed in the idle detent. The vertical speed is increasing through 14,800ft/min.
The airbrakes are deployed.
For the remainder of the descent to impact with the sea, the verbal exchanges continued to indicate that none of the three pilots on the flight deck could understand what was going on sufficiently well to take effective recovery action. They appeared to be experimenting with different control positions, including introducing rudder inputs, but none of the pitch inputs to the sticks were nose-down except momentarily.
When the impact came, the sidestick on the left side had a nose-down and right-roll input, the right hand sidestick was on the nose-up stop with neutral roll input.