The late Roy Underdown was Principal of the College of Air Training, Hamble. David Cockburn is an experienced pilot and flight instructor. His varied flying career includes service with the Royal Air Force's electronic warfare and radio aid calibration squadrons. He has taught in several training organisations, military and commercial, as a ground instructor, and at the time of this revision was a teaching advisor in the Aeronautical Sciences Department of the King Faisal Air Academy in Riyadh, Saudi Arabia.