Andreas Lubitz, the co-pilot who steered a Germanwings flight into a mountainside, had a history of depression so debilitating that he left his pilot training program for six months in the late 2000s, reports Germany's Bild newspaper.

When he was ready to return, he had to pass a battery of psychological tests required for pilot certification, as well as another series of tests that were a prerequisite for his job at Lufthansa, which owns Germanwings. But in all likelihood, that was the last time Lubitz's employer or government subjected him to a formal psychological evaluation.

In hindsight, that might seem an instance of negligence. But it's sadly representative of the broader problems with how the aviation industry, and especially budget carriers like Germanwings, have failed to prioritize pilots' psychological health.