Air investigators have been unable to trace a microlight pilot who came within 20 feet of hitting the Red Arrows flight display team while flying over Sutton Bridge.
A report by air investigators the Airprox Board rated the incident of 6pm on June 15 as causing the highest possible danger to the aircraft involved.
The Red Arrows were training for their appearance at the Coronation of King Charles III which took place just two days later, when the incident occurred.
The report says that pilots stated: “The formation had been split into two sections.
“As the rear section had been passing the town of Holbeach (they recall), a microlight had been spotted on the nose in very close proximity.
“Elements of the rear section had just sufficient time to ‘flinch’ upwards and flew over the top and slightly to the right of the microlight at approximately 20ft miss-distance.”
RAF Waddington’s radio controllers told the inquiry that there was ‘garbled’ contact with the microlight pilot and it disappeared from the radar.
An RAF Coningsby investigation said the microlight was outside of their control and had not been communicating with air traffic control.
Members of the board noted that ‘it was disappointing that the microlight operator had not been traced despite the significant efforts’.
Summing up, the board argued the Red Arrow pilots hadn’t flinched early enough ‘to materially increase the separation’.
The report said: “The separation between the Hawk and the microlight had been at a bare minimum, and that the incident was described by the Hawk pilot as a last minute sighting with little time to react.”