This paper focuses on maintenance test flying as pertaining to commercial jet aircraft. Aircraft maintenance manuals or regulatory prescriptions require aircraft to be test flown prior to being released to service, following specific maintenance, repair, overhaul or modification events. Further, such flights might be conducted to accept or return aircraft as demonstration of their serviceability. Similarly, test flights to verify aircraft performance are at times required.

Such maintenance test flights are mostly conducted by pilots rated to fly those aircraft primarily in commercial line operations, typically with no or little training on such specific maintenance or performance test flight procedures or techniques. The international regulatory environment remains in flux with discussion ongoing.

In conducting such flights a pilot is exposed to activities outside the normal aircraft standard operating procedures up to the edge of the operational flight envelope. Whilst not intentional, abnormal aircraft behaviour can nevertheless result in inadvertent flight outside the envelope with a consequential potential loss of control. History has shown that the predominant cause of fatal accidents during maintenance test flying result from complex loss of control scenarios not recovered or not recoverable. This raises the question of adequacy of pilot training.

Maintenance test flights are a necessary component for the industry to maintain its exceptional safety standards and minimising loss of life. But such flights in themselves remain demonstrably one or two orders of magnitude more risky than commercial flights.