Passengers appeared to have noticed nothing out of the ordinary, but Alps-crash copilot Andreas Lubitz had practiced his descent-programming skills on a previous flight.

He apparently waited until the pilot stepped out of the cabin, after which Lubitz set about his nefarious business:

Over the course of three or four minutes, Lubitz…designate[d] “100 feet” as the selected flight level. He did this several times, while the pilot was out of the cockpit.

But this was just after the plane had already begun its descent. After each occasion that he chose “100 feet” he then corrected himself and entered the correct flight level. The course of the plane was not altered at all.

So no one noticed at all. Here’s how it went:

LubitzProgram

The article speculates that, although no one knows what was in Lubitz’s mind at that point, he seems like a “man steeling himself for the challenge he has set himself, building up the courage but at each point pulling back – until finally the pilot re-enters the cockpit and normality returns.”

Perhaps. But my theory is that he may have been purposely desensitizing himself to the act of setting the altitude so that it became more and more routine, as well as testing whether he could get away with it. By the time he decided to follow through on the return flight, he was calm, collected, and ready.

And those people who were on the outbound Germanwings “test” flight that left Duesseldorf at 06:01 and arrived in Barcelona at 07:57 on the March 24, 2015 can thank their lucky stars that it seemed to be—and functioned as—an ordinary, uneventful trip. But now they know what was actually happening.

At the end of the article we see the following:

Were you on the outbound Duesseldorf to Barcelona flight in March? Have you been affected by the issues raised in this story? You can email haveyoursay@bbc.co.ukwith your comments.

I would be very interested in reading any responses from the passengers.

[Neo-neocon is a writer with degrees in law and family therapy, who blogs at neo-neocon.]