The Pawnee registeredG-ASVX was a single-engined single-seat crop spraying aircraft built in 1974. The Phantom serial numberXV493 was a twin-engined two-seat, all-weather military strike/interceptor aircraft.
Accident
The Pawnee had departed earlier on 9 August 1974 from Southend Airport to a disused airfield at Broomhill, near Downham Market in Norfolk. Broomhill was used as a temporary base to refuel the aircraft and to load pesticide. At about 14:04 the aircraft had finished spraying a field south of Broomhill and was returning to replenish the pesticide hopper. The Phantom departed RAF Coningsby at 13:51 to fly a low-level navigation and reconnaissance flight at no lower than above ground level. The Phantom was following a standard low-flying route; the Pawnee pilot was aware that military low-flying routes were in the area but the exact routing was classified and not released by the military. About 14:08 about west of the village of Hilgay, and at an estimated height of around the Phantom, flying at a speed of about, struck the Pawnee on its right side. The Pawnee disintegrated, while the Phantom, on fire and shedding parts of its structure, continued on its heading for a further before it hit the ground inverted. All three aviators were killed: the pilot and navigator of the Phantom and the pilot of the Pawnee.
Investigation
Both aircraft were found to have been maintained correctly and were legally authorised for the flights. Farmwork Services, who had chartered the Pawnee, had informed the local police authority about their proposed operation and type of chemical to be used. Nothing in the regulations required them to inform the military although Farmwork Services had, as usual, informed nearby RAF Marham that they would be spraying an extensive area of Norfolk between June and the end of August 1974. Investigation of the wreckage failed to determine if either had a working anti-collision light and it was only possible to determine the height of the accident by the use of eyewitness accounts. The collision occurred in good visibility at an estimated height above ground level of. The investigation could find no evidence to suggest that either of the pilots had a medical problem or that either aircraft had any defect that would have contributed to the accident. The rules of the air state that the Pawnee should have given way to the Phantom which was closing from the right. But it was accepted that at a closing speed of about the time needed by the Pawnee pilot to assess the situation and execute a manoeuvre was minimal. It was also a requirement of the Phantom pilot to make sure that he did not collide with the Pawnee but clearly in this accident the lack of time was an element. Also the military aircraft had only just turned on to the heading and with the Pawnee 15° to his left the view may well have been obstructed by the Phantom's canopy frame. While it accepted the need for the Royal Air Force to practise low level high-speed flying the investigation report was concerned about the lack of information on the military low-flying route available to civil pilots, particularly those involved with crop spraying, pipeline, and powerline inspection.
Cause
The investigation determined "The accident occurred because neither pilot saw the other aircraft in time to avoid collision. The 'see and be seen' principle was inadequate for preventing collision in the circumstances that existed. A significant feature which contributed to the accident was the absence of any system for co-ordinating military and civil low flying activities in the low flying areas and link routes."
Recommendations
The accident report made seven recommendations:
That the location and vertical extent of the low flying areas and link routes should be made available.
Private pilots should be alerted to the nature of military low flying activities and the need to avoid them.
An advisory service be provided to enable civil pilots to co-ordinate their activities with the military.
That civil aircraft involved in low-flying activities should be painted as conspicuously as possible and fitted with high power collision warning lights preferably strobe type. Also recommended that the military consider fitment of strobe type high power collision warning lights to aircraft engaged in low level training.
The military review their need for airspace for low level high speed operations and withdraw any areas not needed.
That the upper limit of the military low flying link routes be limited to instead of, if not possible then should be considered.
That the rules of the air be amended to allow aircraft with the right of way to climb and if necessary pass over the other aircraft.
