US and RAF planes in mid-air dispute over Norfolk
An RAF pilot told a US Air Force plane he "had every right to be there" after being accused of flying too close to US parachutists in Norfolk, a report said.
A US Hercules from Mildenhall, Suffolk was training over Sculthorpe in Norfolk at the same time an RAF Tornado was flying nearby in November.
The UK Airprox Board, which investigates near-misses, concluded both planes had the right to be flying.
The board said better co-ordination was needed between both air forces.
The Tornado GR4 was one of a pair from RAF Marham in Norfolk which were taking part in their own exercise.
The board heard the US Hercules MC130 filed a report to Airprox after the incident happened at about 12:30 GMT on 7 November.
It came after the pilot felt the RAF plane was flying too close and, although not a threat to his plane, he was concerned about the safety of the parachutists being dropped.
The board heard the two planes were about 1.5 miles (2.4km) apart when concerns were raised by the US plane whose pilot was "clearly frustrated by the continued presence of the Tornados".
The Tornado crews said the Hercules was always visible and they remained clear of the parachutists.
The board concluded both pilots were entitled to be operating in the area and the incident was one of "differing perceptions".
Some members of the board said they felt the Tornado pilot could have been more flexible once informed of the concerns of the US pilot.
The board had already recommended better co-ordination between controllers at RAF Marham and the USAF Mildenhall, but said it was "heartened" to hear this was continuing and a consultation paper was due to be published shortly.