Germanwings interim report from BEA

French accident investigator BEA, in today’s interim report on the 24 March suicide crash in the Alps, tells us what we already know about the fatal flight itself, but in greater detail.

It has, however, added some information from the flight data recorder about the first flight that day. Remember, this aircraft and the same crew took off from Dusseldorf that morning for Barcelona, but it was on the return trip later that the copilot took the fatal action he planned.

The detail the BEA provides on a particular couple of minutes during the outbound flight is –┬áIn the light of what we know eventually happened – chillingly macabre, but pretty pointless in terms of what action could usefully be taken as a result of knowing it.

With the aircraft in the cruise at FL370 (37,000ft) over France, the captain leaves the flight deck, so the copilot is in control. At that moment the aircraft is handed over from Paris air traffic controllers to the Bordeaux sector, and they tell the crew to descend to 35,000ft. The copilot acknowledges this, sets 35,000ft in the flight control unit of the autopilot, and executes that selection so the aircraft begins its 2,000ft descent.

What happens next is the weird part. The copilot then dials the FCU altitude all the way down to 100ft, then all the way up to 49,000ft – but does not pull the button to execute either of the extreme settings, so the original 35,000ft selection is still in charge. Then he returned the selection to 35,00ft again anyway, just before Bordeaux gave another descent instruction to FL210 (21,000ft), which the copilot selected. But having done so, he indulged in another dialling exercise, again selecting 100ft – the fatal altitude selected to cause the crash in the alps. Then, however, he returned it to the cleared altitude.

Just after that the captain buzzed to re-enter the cockpit, and the copilot admitted him.

So what does this little apparent mental rehearsal tell us? That emotionally unbalanced people experiment with ideas before carrying them out? That is not new information.

But his experiment has now been discovered, so maybe flight data monitoring would predict other such events. Could it?

Pilots under high workload with multiple tasks to perform and monitor can easily dial straight through the intended altitude on the FCU because their attention was distracted, then have to reset it. What are we to make of that in the future?

Hindsight is so easy.