Description

On 23 July 2011, a Boeing 757-200 being operated by Thomson AW on a passenger flight from Verona Italy to Glasgow was involved in a near miss with a Discus Glider whilst descending through 3450 feet QNH in Class ‘E’ airspace east of Glasgow and under radar control in day Visual Meteorological Conditions (VMC). The glider was working a local aerodrome frequency and had been observed intermittently on radar but with insufficient continuity to do other than to provide a general alert to the 757.

Investigation

An Investigation was carried out by the UK Airprox Board. It was established that both aircraft had been in compliance with the operating requirements applicable to Class ‘E’ airspace and that at the time of the conflict, the white-coloured Discus BT glider had been climbing in a thermal during a cross country VFR flight from and returning to a designated gliding site at Portmoak located 44 nm north east of Glasgow Airport. The in flight visibility was reported to have been around 30 km.

The airspace involved was beneath Class ‘D’ airspace which commenced above 6000 feet and constituted a narrow corridor between adjacent blocks of Class ‘D’ airspace which extended on both sides below 6000 feet. The significant difference in Class ‘D’ for VFR traffic was noted to be the requirement to work the controlling ATC Unit and obtain a VFR clearance to operate, whereas there is no requirement for VFR traffic to work any radio frequency in Class ‘E’ airspace. It was found that the glider had a local non radar-equipped aerodrome frequency selected and was listening out with no evidence that he had called this facility. The glider was not fitted with a transponder.