Julian Tutt reports

Dr Ian Perry, an examiner of pilots for the Civil Aviation Authority and the Federal Aviation Authority, tells the BBC's The Airshow that many doctors are grounding pilots for fatigue, but giving another reason on official reports.

He admits he himself covers up the extent of the problem, which could be a factor in plane crashes.

Research shows 70% of crashes are due to pilot error.

Air experts fear the growing number of long-haul and package holiday flights and pressure to reduce crewing levels is putting pilots under extreme pressure.

And a proposal before the European Commission to allow airlines to set their own maximum limit on flying time could make things worse.

The British Airlines Pilots' Association wants an eight-hour flying limit.

Company image

Dr Perry said pressure to cover up the fatigue problem came from both pilots and airlines: "If many of my colleagues were honest, we ground more people for that problem, but we don't call it that problem.

Dr Ian Perry admits he covers up the extent of pilot fatigue

"Airlines are loathe to admit there is such a problem because that looks bad on them from the company image, and we have had many a company turn round and say that this pilot is malingering, or he has got other problems."

Dr Perry says he has recorded fatigue problems as chest infections.

The Airshow says the cover-up flies in the face of confidential reporting measures which are designed to encourage pilots to admit their failings and so improve air safety.

One airline that admits the problem is Air New Zeland. Its research on pilots on demanding routes is only just beginning to reveal the extent of the problem.