A formation of planes flying over the North East came close to crashing with an "unknown object," a report has revealed.

The UK’s Airprox board assessed an incident on the morning of May 17 that saw a formation of planes come close to colliding with an “unknown object” – which the pilot believes to be a drone.

The two-plane formation was cleared by Teesside Air Traffic Control for a left-hand run-in and break manoeuvre to join onto the traffic pattern at Teesside Airport to land.

The incident carried a “high risk” of collision according to the aviation body, as the drone was at the same altitude as the two planes, and was only around 50 feet away.

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The board gave the incident a risk rating of B – which is the second-highest near-miss rating.

As they were descending, the pilot on the right-hand side of the pair spotted what they assumed to be a “black drone” about 50 feet away. The drone proceeded to pass between the two planes, but the aircraft in formation were able to land without further incident.

The incident occurred 4.8 nautical miles away from the runway at Teesside airport, above Stockton, whilst the planes were descending past 1700 feet.

The Airprox Board said: “In the Board’s opinion the reported altitude and/or description of the object, combined with the absence of any indication of a drone’s presence from drone detection data, were such that they were unable to determine the nature of the unknown object.

“The account of the incident given to the board is as follows: “[The Falcon 20 pilot reports] they were PF in the LHS and [as part of a two aircraft formation] cleared by Teesside ATC for a left-hand 'run-in and break' to runway 23.

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“The pilot on the rightmost side of the pair and on the RW23 extended centreline, descending to 1500ft.

“Whilst descending past 1700ft and at a range of 4.8NM from Teesside, they observed a black drone pass co-altitude down the left-hand side of the other formation aircraft.

“The range was estimated to be about 50ft. The formation landed without incident and the drone sighting was reported to ATC.”

A spokesperson for the UK Civil Aviation Authority said: "Airprox incidents are assessed by the independent UK Airprox Board (UKAB).

"The Board does not investigate incidents and these published reports are intended to enhance civil and military aviation safety, and the UK Civil Aviation Authority supports and endorses this important contribution to flight safety.

"We do not add further commentary or analysis to individual airprox reports."