The pilot of an RAF Chinook helicopter was forced to take emergency action to avoid hitting three drones flying illegally above London.
The £60 million Chinook was at 1,000ft when the pilot spotted what he initially thought were two seagulls and a helium balloon ahead of him.
But after hurling the huge transport helicopter to the right and missing the objects by just 330ft, the pilot was stunned to see they were actually three drones, each the size of a dustbin lid.
According to a report by the UK Airprox Board into the near-miss, the pilot reported the scare above Wormwood Scrubs Park, West London, to air traffic controllers at Heathrow.
The report says the drones were entitled to be flown from the 150-acre park but the Civil Aviation Authority found they were operating at more than twice the permitted maximum altitude of 400ft.
The Ministry of Defence said the Chinook, which can carry up to 55 troops, was on a training flight from RAF Odiham in Hampshire when the incident happened on March 18.
Investigators rated the scare as Category C, meaning safety had been ‘reduced’ but that the ‘risk was averted’.
A report last year revealed how another Chinook, flying at 138mph and at a height of 2,100ft, came within 130ft of a drone near Farnborough, Hampshire.
Drone operators face up to five years in jail if convicted of endangering an aircraft.