he strain put on airline pilots has been in the spotlight since the co-pilot of a Germanwings flight crashed his plane into the French Alps in March.
French investigators say it was intentional and that Andreas Lubitz had practised a rapid decent on a previous flight. There have also been repeated questions about his mental state.
Meanwhile, the European Commission has announced it is setting up a taskforce of experts to review aviation safety regulation, including pilot health checks, following the crash.
So how much pressure are pilots under?
John (not his real name) found himself exhausted after 36 years in the industry.
He told the BBC: "I just found it impossible to go to work. I felt very close to tears, as I had done on various occasions at the end of shifts, without really understanding what was happening.
"I just couldn't really function on any level."