Flight's safety and operations editor and former RAF flying instructor David Learmount explains how to perform a barrel roll.
"Barrel rolls can be dangerous because they are so gentle and feel so easy to do that even skilled pilots can get complacent about them. If that occurs, it can result in failure to monitor the progress of the manoeuvre, which is actually quite a complex process. The most common unintended outcome is to exit from the manoeuvre at a lower altitude than the entry level.
The same applies to another apparently simple manoeuvre that can be carried out harmlessly – provided the pilot gets it right - in any conventionally controlled aeroplane: the “wing-over” or “chandelle”. A UK Royal Air Force BAE Systems Nimrod crew died in an air show at Toronto on 2 September 1995 when a wing-over went wrong. The aircraft plunged into Lake Ontario.
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In the case of the successful Cimber Air barrel roll, the pilot started it at a very low height above the ground. That does not make a barrell roll more difficult, but it leaves no latitude for error.
If the pilot were to get the manoeuvre wrong and let the nose drop too early in the roll, the result can be terminal. But if the pilot were to realise just in time that the nose has dropped too far too early, recovery can be effected by accelerating the roll rate to achieve wings level, then pulling sufficiently to get the nose up and attain level flight.
Depending on how far the nose has dropped and how much height is left, this can result in overstressing the aircraft by pulling excessive positive G. But it is worth it if that saves the aeroplane.
The essentials for success in a barrel roll are: to start with sufficient speed; to get the nose well up on entering the roll; then not to let the nose drop through the horizon until just after the aircraft has passed through the inverted position; and to keep the rate of roll going steadily throughout so the aircraft recovers to straight and level flight at the same height it was at when it entered."