US Air Force F-15 Eagle Fighter Jets had a near-miss with a civilian glider over Downham Market, a report has revealed.

The UK Airprox Board, which assesses the risk of any close calls in Britain’s skies, released a report on the incident on August 17, which found that the four planes were flying in formation at 335mph and were forced to brake to avoid colliding with a Nimbus glider.

The F-15s were five and a half hours into a drill to RAF Lakenheath, having crossed the English Channel and starting their descent. They had split from two other F-15s in the formation.

The four were in close formation, having descended from 26,000ft to three thousand.

The lead fighter jet was then warned by air traffic control that there was "traffic on the nose", and they were on course to collide with another aircraft.

East Anglian Daily Times: The flight path that led to the near-missThe flight path that led to the near-miss (Image: The UK Airprox Board)

The report said the lead pilot saw the glider just five miles ahead of the formation while 3,700 feet above Downham Market.

Three of the F-15s broke away to the left and right, while the head fighter jet climbed to go overhead of the glider.

The glider was on a path towards March, having taken off from Marham, when the pilot spotted the jets to his left "at close range", the report said.

He attempted to move below the F-15s by speeding up to 100mph to avoid a crash, and passed around 500ft underneath the lead fighter jet and 600ft horizontally.

East Anglian Daily Times: A glider similar to the one involved in the near-missA glider similar to the one involved in the near-miss (Image: ©archant2016)

Both the glider pilot and the lead F-15 pilot assessed the risk as medium, and the report rated it as a Category B degree of risk, the second-highest rating.

The incident is thought to have been caused by the glider and the F-15s not having compatible communication systems, with the report saying they shared responsibility for both the near-miss and its avoidance.

The report also found that the F-15s may have had the opportunity to "kick right" to give way to the glider and prevent needing to do avoidance maneuvers at all. They referred to the proximity of the glider and one of the F-15s as "causing concern".