The Squadron was tasked to carry out a fly-past in commemoration of the 61st anniversary of the RCAF in conjunction with other base aircraft. At the conclusion of the fly-past the three CC-130 crews planned to recover on runway 29 utilizing a low level 'battle' break manoeuvre. They positioned themselves in echelon right with wingspan spacing. The briefed procedure was to pull 10° and turn left with 60° of bank maintaining 2 G's, climbing to 1,000 feet AGL to position themselves downwind. Number 2 & 3 would follow each with three seconds spacing. After approximately 50° of turn at 900 feet AGL number 2 collided with the underside of lead forward of the LH main gear, punching a 5 foot square hole in the aircraft floor structure. The number 2 aircraft had its forward fuselage section separate from the aircraft and freefall into a field. The numbers 3 and 4 propellers separated and landed some distance from the main wreckage. The tail section of the lead aircraft also separated prior to ground impact. Control of either aircraft after collision was impossible. The four occupants of the lead aircraft and the six occupants of number 2 all sustained fatal injuries. Both aircraft crashed inverted and a building and several vehicles were destroyed in a very intense fire. Crew: Cpt Robert William Drake, pilot, Cpt Iain David Mahaffey, pilot, Cpt John Derek Thornton, pilot, Cpt David Arthur Jon Whalen, pilot, W/O William Iver Oness, flight engineer. Passenger: Cpl J. M. Doucet, ATC.
Probable cause (official findings): The Board assigns cause factors as follows: a. Personnel - Pilot - Technique. The pilot (Trucker Lead) deviated from the briefed Battle Break profile to the extent that the designed time, vertical and horizontal separation between Lead and Trucker 2 was lost. b. Personnel - Pilot - Inattention. The pilot (Trucker 2) lost visual contact with Lead and continued the manoeuvre through to impact without reacquiring Lead. c. Personnel - Supervision/435 Sqn - Inattention. 435 Squadron supervisory personnel assigned pilots to perform a manoeuvre in the CC130 for which they were inadequately trained and in the case of two pilots had no training at all. d. Personnel - Management/435 Sqn, CFB Edmonton, ATGHQ - Information. The absence of police with respect to Air Display manoeuvres permitted the planning and conduct to and unpublished procedure. There are no written instructions or Standard Operating Procedures describing the CC130 Battle Break. This manoeuvre was widely used and condoned at all levels.