The fatal mid-air collision last July between a Cessna 177 and a Proteus Airlines Beech 1900D off the French coast raises questions about procedures for separating public transport aircraft operating under visual flight rules (VFR) and instrument flight rules (IFR) in the same area, says France's accidents investigation bureau (BEA).
The Beech 1900D was between Lyon and Lorient, with 12 passengers and two crew on board, while the Cessna 177, with only the pilot aboard, had taken off from Vannes for a local flight when the collision occurred, above the bay of Quiberon, Brittany.
Lorient control authorised the Beech pilot to descend to an altitude of 3,700ft (1,130m), but the pilot cancelled his IFR flight plan, descended to 2,000ft, and began a 360° circuit of a cruise ship to allow passengers to see the vessel.
At the same time, the Cessna 177, in radio contact with Quiberon, began a descent from 3,000ft to 1,500ft. The two aircraft collided at 2,000ft "almost at right angles", says the report. "The accident occurred in uncontrolled airspace where...collision avoidance [depended solely on the pilots'] external vigilance." Lorient radar could not see the Cessna because its transponder was switched off.
The BEA recommends the prohibition of arbitrary cancellation of IFR on public transport flights and improved classification of airspace. It says general aviation pilots should know the rules about transponder use.