Following the revelation that Germanwings flight 4U9525 may have been crashed deliberately, some of the world's largest airlines have confirmed plans to change their cockpit procedures so two crew members must always be present.
The UK's Civil Aviation Authority (CAA) said it had written to airlines to find out what safety procedures they have in place.
It added that pilots have "extensive and regular" medical assessments to ensure they are fit to hold a license.
Aeromedical examiners are required to assess a commercial pilot's mental health at each medical examination which, for an airline pilot flying with at least one other pilot, is undertaken annually. These detailed medical assessments are in line with international aviation standards.
The following airlines have confirmed they will now require at least two people in the cockpit at all times:
- Air Canada
- Air Transat
- Norwegian Air Shuttle
- Air Berlin
- Thomas Cook