AF 447 Thread No. 12

[Uplinker]

AF 447
This was done to me recently in the SIM. I did not know what was coming or what to expect. I probably should not admit to it, since it reveals several mistakes on my part, but for the greater good, here we go.

It was night time. There were no clouds or any weather visible from the cockpit. There was no moon or stars or horizon. The Captain actually got out of his seat; saying he was "going to the loo". After he had gone, I was given a climb from FL350 to FL370. I initially declined the climb, since REC MAX on the PROG page was only showing FL370, however, they insisted, so for the purpose of whatever it was they wanted to demonstrate, I complied. As the aircraft climbed, the airspeed very slowly increased. I thought odd - perhaps an Auto-thrust or speed control fault? Both speed tapes were showing exactly the same thing however, I thought odder still.

I was starting to think about unreliable speed when the over-speed warning went off. I tried to ignore the warning and work out what was happening. Both speed tapes were still identical and steady. The Airbus overspeed warning is extremely loud, extremely insistent, and does not stop (and I forgot how to cancel it). After a few moments of apparently being in overspeed, and the very loud, very insistent warning going, I deployed the speed brakes to no avail. I then pulled the thrust levers to idle. Soon after that, the nose dipped. I thought ah, now I know what they are doing to me; Abnormal V alpha prot. So I followed the OEB for V alpha prot and turned off two ADRs.

This did not help and they froze the SIM with a V/S of -14,000'/min showing.

Now, you are probably all way ahead of me here, but there I was holding full back stick and descending at 14,000 a minute and not understanding what was going on. Sound familiar?

Once they explained what had happened, they released the SIM, and I pitched forward to unstall the wing, added power and safely levelled off.

I was very shaken by this demonstration, in particular how I had ended up holding full back stick having stalled the aircraft.

Several points and recommendations:

1. I did not recognise unreliable speed, or the fact that both the Captain's and F/O's pitots had frozen up simultaneously during the climb. I did not follow the unreliable speed drill.

2. I did not recognise that the aircraft had stalled. This was in the SIM, and there was no airframe vibration or reduction in external wind noise to give clues about reducing airspeed. Nevertheless, I did not recognise the stall, despite the sudden nose drop.

2a. When they froze the SIM so we could see what was going on, I agreed with their diagnosis but said, 'but the audible "stall stall" did not go off'. They said "yes it did". So it was sounding but I literally did not hear the audio saying "stall stall".

3. I, like many at the time of AF447, said that I would never be stupid enough to hold full back stick. But that is exactly what I did - thinking I had a V alpha prot problem.

4. Unreliable speed does not necessarily manifest itself as one wildly fluctuating or stuck speed tape while the other one moves normally - which was the only demonstration of unreliable speed that I had previously been shown.

5. The over-speed alarm is far too strident. It blocks the brain, preventing sensible thought. It should not be a continuous repetitive chime. Overspeed of a few knots is not going to kill anyone, or even damage the plane actually.

6. If the aircraft stalls, there needs to be haptic (vibrating) feedback from the side-stick, like a stick shaker, and all other audio needs to be suppressed except just the "stall stall".

~ According to human factors research, our hearing is the first sense to shut down when we become overloaded. So there needs to be a physical vibrating feedback to alert the pilot, and the amount of audio alerting needs to be kept to a minimum - only the most important thing at any point should sound.

7. It is high time and extremely important that a method of measuring airspeed is urgently developed that is not susceptible to interference or incorrect reading under icing conditions.


I made mistakes during this SIM demonstration and missed cues and clues that I probably should not have missed. But in my defence, I have never seen them in the form they were presented to me. It is one thing to read about failures in a book, but one should really experience the most safety threatening failures. I am not proud about this but I am hopefully a better pilot now. In future, if anything on the PFD ever looks unusual, (or even impossible !), I will take out the autopilot and the auto-thrust and set 2.5 degrees up and around 83% N1 (in the cruise). This will keep us safe and flying normally while we work out what has gone wrong.

I take back anything I might have said about the crew of AF 447.