On 13 August 1996, a Bombardier Learjet 25B being operated by a Spanish Air Taxi Operator on a private charter flight from Palma de Mallorca Spain to Northolt made a high speed overrun of the end of the landing runway after an approach in day Visual Meteorological Conditions (VMC) and collided with traffic on a busy main road after exiting the airport perimeter. All three occupants - the two pilots and one passenger - suffered minor injuries as did the driver of a vehicle hit by the aircraft. The aircraft was destroyed by impact forces but there was no fire.
An Investigation was carried out by the UK AAIB. The accident airport, Northolt, is unusual in that it operated by the Royal Air Force for both military and non scheduled civilian traffic.
It was noted that the accident aircraft did not have - and was not required to have - a Cockpit Voice Recorder (CVR) fitted and that the crew had not received - and were not required to receive training in Crew Resource Management. It was found that the aircraft had been serviceable prior to the accident. It was established that the aircraft commander had been PF and that a PAR approach had been flown in VMC but with the PF remaining on instruments until the designated Decision Height in order to gain maximum training value from what was a rare opportunity for a civilian flight crew to receive PAR service. The authority gradient in the flight deck was identified as considerable and in addition the First Officer had limited competence in the English language, a factor made worse by his unfamiliarity with both UK military ATC R/T and in particular the R/T especially used for a PAR.
It was noted that the aircraft commander did not appreciate at the time that having crossed the runway threshold slightly high and fast, the touchdown point was much further down the runway than was desirable. With only 952 metres of runway remaining, this, plus he fact that he then forgot to deploy the spoilers, was found to have made the overrun inevitable, with the minimum landing distance actually required having been estimated subsequently at 1411 metres. The First Officer had not monitored the landing, instead being more concerned with the likely taxi route of the aircraft after landing. The aircraft was estimated to have left the end of the runway at a speed of about 70 knots and after colliding with three approach lights, it then passed through the perimeter fence and demolished several of its concrete posts before hitting a van travelling along the main road just beyond and coming to a stop on this road with the van embedded in the right hand side of the fuselage.
It was noted that the proximity of a main road to the end of the accident runway had contributed to the severity of the accident and that the overrun distance would have been reduced by a gravel arrester bed.
Aerial picture of the accident site, Northolt UK, 13 August 1996
Causal Factors identified by the Investigation, quoted verbatim, were:
- The commander landed the aircraft at a speed of 158 (+/- 10) knots and at a point on the runway such that there was approximately 3125 feet of landing runway remaining.
- The commander did not deploy the spoilers after touchdown.
- The First Officer did not observe that the spoilers had not been deployed after touchdown.
- At a speed of 158 (+/- 10) knots with spoilers retracted and given the aircraft weight and atmospheric conditions prevailing, there was insufficient landing distance remaining from the point of touchdown within which to bring the aircraft to a standstill.
- The commander allowed himself to become overloaded during the approach and landing. The safeguards derived from a two-man crew operation were diminished by the First Officer’s lack of involvement with the final approach.
The Final Report of the Investigation was published on 3 July 1997 and may be seen in full at SKYbrary bookshelf: Aircraft Accident Report 3/97
Four Safety Recommendations were made as a result of the Investigation, one whilst it was in progress and the remainder at publication of the Final Report and are reproduced below as published:
- The Ministry of Defence should take note of the CAA follow up actions on Recommendation 94-15 with a view to assessing their applicability to those Government Aerodromes having a significant number of movements by civil aircraft and military aircraft with similar characteristics which are adjacent to public areas such as major roads or railways. (96-67 made on 2 October 1996)
Safety Recommendation 94-15 was made as a result of a similar overrun accident by an executive jet onto a main road at Southampton in 1993: C550, Southampton UK, 1993 (RE HF WX FIRE) - “The CAA should review all licensed UK airfields to identify potential safety hazards beyond current Runway End Safety Areas (RESAs) and identify the need for, and practicality of installing, ground arrester systems”
- The Ministry of Defence should consider harmonising its ATC procedures with those laid down in the Manual of Air Traffic Services Part 1 as published by the CAA. This should be done to avoid the use of non-ICAO phraseology and procedures when controlling civilian air traffic at RAF airfields. (97-8)
- The Ministry of Defence, in the light of the total number of movements at the airfield and its close proximity to densely populated areas, should give further consideration to the installation of an ILS/DME system at RAF Northolt. (97-9)
- The Spanish Dirección General de Aviación Civil should begin to implement the planned requirements for CRM training, in accordance with ICAO guidance, as soon as possible and in advance of the adoption of the CRM training requirements of JAR OPS (97-10)