AIR safety bosses have questioned whether gliders should be made more visible after an RAF plane travelling at 289mph came within 300ft of an unpowered aircraft performing gentle turns.

It has emerged the incident, at Boltby, near Thirsk, at 3.45pm on February 20, happened due to late sightings by both pilots, with the rear-cockpit instructor of the Tucano from RAF Linton-on-Ouse, near York, spotting the glider as it passed below him at an altitude of 5,400ft.

A UK Airprox Board report into the near-miss found the Glaser-Dirks glider pilot was first alerted to the proximity of the Tucano, which was flying to Durham Tees Valley Airport (DTVA) for a practice diversion, by hearing its engine.

It found the glider pilot may have been working hard to maintain lift, and this would have focused his attention ahead, to the detriment of his ability to see the small and fast-moving Tucano as it approached from behind his wing-line.

The report states: "By the time the glider pilot acquired the Tucano visually, there was probably little he could do to influence events and hence why he took no avoiding action as he saw the aircraft pass above him."

The incident was reported during a handover conversation to DTVA radar and neither pilot took avoiding action.

The report found the combined radars of RAF Linton, DTVA and a selection used by the Radar Analysis Cell were not able to detect the glider, which had been performing gentle turns near Sutton Bank, the base of Yorkshire Gliding Club.

It states: "The Vale of York is a particularly busy area, and it is sometimes not well understood that gliders will operate up to 19,500ft or higher when conditions and regulations permit."

The glider pilot assessed the risk of collision as "medium".

The Tucano pilot said the glider had been a "difficult spot" against the backdrop of the white clouds.

The report added measures to make gliders more conspicuous, such as radar reflectors, paint and having compatible traffic collision avoidance systems fitted in all aircraft, would help in preventing mid-air collisions.

The board heard the use of radar reflectors in gliders to enhance their conspicuousness had been discussed on many occasions, but there had been "little enthusiasm from the gliding community".

It stated: "Both pilots had equal responsibility for collision avoidance and not to fly into such proximity as to create a danger of collision."