On 14 June 2009, a Grob 115E Tutor being operated by the UK Royal Air Force (RAF) and based at RAF Benson was conducting aerobatics in uncontrolled airspace near Drayton, Oxfordshire in day Visual Meteorological Conditions (VMC) when it collided with a Standard Cirrus Glider on a cross country detail from Lasham. The glider was sufficiently damaged that it could no longer be controlled and the glider pilot parachuted to safety. The Tutor entered a spin or spiral manoeuvre which it exited in a steep dive from which it did not recover prior to a ground impact which killed both occupants.
An Investigation into the accident was carried out by the UK AAIB. It was established that the Tutor had been conducting an air experience flight for an Air Cadet and that the single seat glider was flying cross country on a 300 km task that had been suggested by his gliding club. At the time of the accident both aircraft were operating in uncontrolled airspace notified as the Oxford Area of Intense Aerial Activity (AAIA) which was relatively congested, especially with gliders, in the prevailing good weather conditions. Neither aircraft was in receipt of an air traffic service at the time of the collision and both were relying on the ‘see-and-avoid’ principle for collision avoidance. No onboard traffic alerting system fitted to the Tutor and the FLARM collision alerting system fitted to the glider was not designed to detect the transmissions from transponders such as that fitted to the Tutor.
When the collision occurred, at approximately 4150 ft amsl, the glider was on a constant track and the evidence indicated that the Tutor pilot had not seen the glider before he pulled up into a vertical manoeuvre. When the glider pilot became aware of the Tutor and attempted to take avoiding action this was unsuccessful. The outer section of the left wing of the Tutor had struck the fin and right tailplane of the glider causing the glider tail section to break away. There was no evidence that any part of the glider had penetrated the cockpit of the Tutor and it was concluded that after the collision, the aircraft had been capable of controlled flight. The apparent lack of recovery of the aircraft or of any attempt to abandon it once it was out of control, led to the conclusion that it was likely that the pilot had sustained a fractured spine as a result of the impact of the collision. Following the collision, the cadet was suspected to have released their harness and moved the canopy operating handle to the open position but that, although they had been shown the Tutor passenger safety video prior to flight, the first action required to remove the canopy prior to abandoning the aircraft - removal of the red ‘jettison’ handle from its housing, had not been taken.
It was found that the Tutor pilot had a chronic medical condition, Ankylosing Spondylitis, which restricted the mobility of his head and therefore affected his ability to maintain a look out to the prescribed RAF standard.
The Investigation determined that the Cause of the collision was that “neither pilot saw each other in sufficient time to avoid the collision.”
Contributory Factors were identified as that:
- The Tutor pilot’s medical condition, Ankylosing Spondylitis, limited his ability to conduct an effective look-out.
- The high density of traffic, in an area of uncontrolled airspace, increased the risk of a collision.
A total of 13 Safety Recommendations were made as a result of the Investigation. Whilst the Investigation was in progress, the following Recommendation as made on 21 July 2009:
- that No 1 Elementary Flying Training School of the Royal Air Force review the passenger safety brief relevant to the Grob GE115E (Tutor) to ensure that passengers are briefed on the circumstances when the harness Quick Release Fitting may be released and the procedure to operate and jettison the canopy, when sat in the aircraft immediately prior to the flight.
The remaining 12 Recommendations were made at the completion of the Investigation and were as follows:
- that the Royal Air Force standardise the terminology used to describe the canopy ‘jettison’ handle (locking lever) fitted to the Grob 115E (Tutor) in order to avoid confusion and to clarify its function.
- that the European Aviation Safety Agency review the certification of the canopy jettison system on the Grob 115 E, to ensure that it complies with the requirements of CS 23.807 with specific regard to the jettison characteristics up to VDO and simplicity and ease of operation.
- that the Royal Air Force consider standardising the position and operation of the D-ring on parachutes used in Tutor, Viking and Vigilant aircraft.
- that the Royal Air Force ensure that the medical history of pilots is reviewed when they initially apply to join an Air Experience Flight.
- that the Royal Air Force ensures that all medical limitations relating to Air Experience Flight pilots are recorded in their F5000 (record of flying training).
- that the Royal Air Force review their policy on pilots flying with Ankylosing Spondylitis.
- that the Royal Air Force review their policy for the retention of the complete flying training records of Volunteer Reserve pilots, so that they are available to their supervising officers
- that 1 Elementary Flying Training School review their risk assessment for Air Experience Flight aircraft operating in areas of high traffic density.
- that the Civil Aviation Authority, in light of changing technology and regulation, review their responses to AAIB Safety Recommendations 2005-006 and 2005-008  relating to the electronic conspicuity of gliders and light aircraft.
- that the Civil Aviation Authority liaise with the Sporting Associations and the Ministry of Defence, with a view to developing a web-based tool to alert airspace users to planned activities that may result in an unusually high concentration of air traffic.
- that the Royal Air Force review the communication procedures between military Air Traffic Control units and Air Experience Flights to ensure that the supervising officer is made aware of significant changes to the local flying environment.
[2010-043] Bold text
- that the Royal Air Force review their policy concerning cockpit checks undertaken to support medical assessments.
The Final Report of the Investigation was published on 14 September 2010.
- ^ Previous AAIB Safety Recommendations
Following mid-air collisions involving two gliders in April 2004 and a helicopter and microlight aircraft in July 2004, the AAIB issued the following Safety Recommendations to the CAA:
Safety Recommendation 2005-006. It is recommended that the Civil Aviation Authority should initiate further studies into ways of improving the conspicuity of gliders and light aircraft, to include visual and electronic surveillance means, and require the adoption of measures that are likely to be cost-effective in improving conspicuity.
The CAA rejected this recommendation. In their response they stated that ‘…it is considered most practicable at this time to enhance publicity of the risk of collision through poor or inadequate visual outlook.’
Safety Recommendation 2005-008. It is recommended that the Civil Aviation Authority should promote international co-operation and action to improve the conspicuity of gliders and light aircraft through visual and electronic methods.
The CAA rejected this recommendation insofar as it was directed to light aircraft for the same reasons given in their response to Safety Recommendation 2005-006. At the time, the CAA stated that they had no regulatory power to require adoption of the recommended measure by gliders.
In 2008 the CAA proposed to widen the mandatory carriage of Mode S transponders to the majority of the aviation community. Following a public consultation exercise, the CAA withdrew this proposal and instead introduced small volumes of airspace where transponder carriage would be mandatory.