In March 2015 a Germanwings co-pilot deliberately crashed his aircraft in the French Alps. 150 people died. Three days later, on Friday 27 March 2015, the German aviation industry association BDL announced a provisional procedure. Two authorized crew members must always be in the cockpit. In April 2017 the BDL announced that the large German airlines would drop the rule by 1 June. Die Evaluierung hat gezeigt, dass die Zwei-Personen-Regelung keinen Sicherheitsgewinn bringt. The evaluation has shown that the two-person rule brings no gain in safety. Opening the cockpit door more often, the BDL said, created additional risk that unauthorized people would get in.
A rule written in three days stayed only until it had been evaluated.