Two F15 warplanes from RAF Lakenheath were involved in a near miss incident with an airliner.
An official report states the Boeing 737 was over Doncaster on October 11, when the F15s were on their way back to their base from the Vale of York area.
The civilian aircraft was given clearance to descend to 29,000ft by air traffic controllers, then instructed to stop its descent at 30,500ft after the military aircraft were seen climbing rapidly towards it.
The F15s had requested clearance to climb to 29,000ft, but were told not to ascend above 24,000ft after a controller saw the B737.
The jets were then asked whether they could fly at 28,000 for the remainder of their journey to Lakenheath, although no instruction to climb was given.
But the F15s may have mistaken this for permission to continue climbing, says a report to the UK Airprox Board.
It says the aircraft came within 3.9 miles horizontally and 2,200ft vertically. It adds there was no risk of a collision, while air traffic controllers rated the severity of the incident as low.
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