On 3 October 2015, a Beech B200 Super King Air (G-BYCP) being operated by an unidentified UK company on an IFR business flight from Stapleford to RAF Brize Norton crashed shortly after take-off in an out of control condition which had begun in day IMC. The aircraft was destroyed by the impact and a post-crash fire, and both the pilot and the only passenger were killed.
An Investigation was carried out by the UK AAIB. The aircraft was not fitted with crash-resistant on-board data recorders or TAWS, nor was it required to be. However a good reconstruction of most of the flight path was accomplished using radar data from four installations in the general area.
It was established that the flight was being operated with two company employees on board (one being the pilot - the aircraft could be operated by either one or two pilots) in order to pick up two passengers at Brize Norton for onward travel. The 40 year-old pilot held a CPL/IR valid on Multi-Engine Piston aircraft and occupied the left pilot seat whilst the other employee occupied the right seat. He had a total of 1,941 total flying hours but almost all (1,791 hours) had been flown on single engine aircraft. He had obtained his King Air type rating in June 2014 and had renewed it in May 2015 before commencing line training with the accident aircraft operator in August 2015. He had passed his final line check 6 days prior to the accident and the operator advised that this had been conducted in "generally good" weather although noted that "he had not been required to fly an IMC departure from Stapleford Aerodrome". At the time of the accident, he had flown 6 hours 40 minutes in command on type (P1) and 113 hours as in command under supervision of the aircraft commander (P1/US). The passenger was also a qualified pilot and held a current ATPL valid on the Bombardier Challenger 300 and the Embraer ERJ 135/145 but not on the King Air.
The planned departure time was 0815 but poor visibility at Stapleford meant that the departure was delayed for an hour until "trees were visible just beyond the end of Runway 22L, indicating that visibility was at least 1,000 metres and the pilot decided that conditions were suitable for departure". The generally prevailing low level weather conditions in the planned direction of departure were advised to the Investigation as having been "poor...with some widespread areas of low cloud and/or fog" associated with "very poor visibilities (and) the top of the fog and/or cloud generally around 1,000-1,500 feet amsl with little or no cloud above this level". The nearest airport to Stapleford reporting present weather conditions was London Stansted which, shortly after the time of take-off, was giving fog with a visibility of 600 metres and sky obscured.
The aircraft took off at 0908 and was observed from the ground to climb "in a wings level attitude until it faded from view shortly after take-off". The pilot's intention prior to take-off was to turn right once safely airborne and track toward the BPK VOR on the 128° radial climbing not above 2,400 feet QNH so as to remain clear of the London TMA. Radar data showed that the aircraft had begun the right turn as it passed approximately 750 feet QNH (565 feet aal) and had continued to climb in the turn until it reached 875 feet QNH after which it began to descend. This descent continued "until the aircraft struck some trees at the edge of a field approximately 1.8 nm southwest of the aerodrome". The impact and consequent fire were not survivable.
Ground track data with the departure runway visible at top left [reproduced from the Official Report]
Using radar data, it was possible to estimate the mean rate of the achieved climb after take-off as 1,500 fpm and the descent which followed as occurring at a rapidly increasing rate which eventually exceeded 7,000 fpm. The final recorded ground speed was 188 knots shortly before radar coverage ended at 230 feet agl. Various radar sources all produced similar estimates of the ground track as reproduced in the illustration above. Available data facilitated simulator modelling of the flight to be carried out which allowed the aircraft manufacturer to undertake flight performance analysis. This work allowed the Investigation to consider more broadly the likely development of the loss of control which had occurred and some of the potential explanations for it. Various observations were made based on the various sources of evidence available. They included the following:
- There was no evidence that the aircraft had not been airworthy when it departed or that any subsequent and relevant loss of airworthiness occurred. The possibility of flap asymmetry was conceded but it was considered that although this may have constituted a distraction, it "would not have been sufficient in isolation to cause a loss of control".
- The aircraft began to descend from its maximum achieved altitude after it exceeded 30° angle of bank, possible reaching a maximum bank angle of 55° to the right, and this was "probably" the result of the increase in bank angle occurring without a corresponding pitch input.
- Had a TAWS been fitted to the aircraft, it would have annunciated bank angle and sink rate alerts at a point where "sufficient height remained to allow the aircraft to recover to safe flight".
- At impact, the landing gear was retracted and the power setting on both engines was still relatively high although "the downward flight path angle had reduced to approximately 5° to 9° and the angle of bank to approximately 12° right". This late change in aircraft attitude "showed that the aircraft was controllable in roll and pitch immediately before impact" and "suggested a conscious attempt to recover the aircraft. This was likely to have occurred either because of one or both of the occupants had gained an appreciation of the extreme attitude of the aircraft either from the flight instruments or by external visual reference which may have been regained as the aircraft descended.
- The post mortem examination of the pilot found evidence of a previously undetected cardiovascular condition "which indicated that he might have suffered symptoms ranging from impaired consciousness to sudden death". This condition "might have occurred spontaneously or have been the result of forces transmitted through the body during the accident sequence and pathology alone was unable to resolve these opposing possibilities". The report on the examination stated that "if there is no other cause identified for the crash then it is both possible and plausible that this was the precipitating factor". Had there actually been a sudden impairment in the pilot's ability to perform his normal duties in flight, then on the evidence available "it suggested that the (other occupant) took recovery action but not in time to achieve climbing flight before the aircraft struck the ground".
Other matters of interest in relation to the accident were noted as:
- FDR/CVR Carriage - although EASA have indicated that "rulemaking" is planned on the requirement for smaller aircraft to carry a CVR and/or FDR, an NPA planned for the first quarter of 2016 had not appeared by the time the Investigation was concluded.
- Passengers on the flight deck - applicable regulatory requirements defined the second occupant as a passenger because as a pilot, he was not qualified on type.
- Single pilot operation - The operator permitted single pilot operations of aircraft so certified and had conducted a risk assessment to assess what defences could serve to prevent an 'Undesirable Operational State' (UOS) developing during such operations and what defences could serve to recover from one. The output from this risk assessment was noted to have been "consider mandating the presence of [an] additional crew member or second pilot on every flight for the King Air Fleet". The operator had agreed with the UK CAA that a role of "additional crew member" would be defined for their single pilot operations. These persons would have "no operational control of the aircraft" but would assist the pilot by reading checklists, conducting radio communications, monitoring the actions of the pilot and assisting if required and "expressing their opinion" on any action taken by the pilot that "may seem abnormal or unclear". However the aircraft type part of the Operations Manual made no mention of "additional crew members" and stated that the "Normal Procedures" section of that part of the Manual "assumes that a second pilot is carried" and that they carry out the PM role which would, inter-alia, involve "monitoring the flight path and pointing out un-planned deviations" which would include calling out 'Bank Angle' if that angle exceeded 30° and 'Sink Rate' if the case of "an excessive rate of descent according to phase of flight and altitude".
The formally-stated Conclusion of the Investigation was as follows:
"Examination of the powerplants showed that they were probably producing medium to high power at impact. There was contradictory evidence as to whether or not the left inboard flap was fully extended at impact but it was concluded that the aircraft would have been controllable even if there had been a flap asymmetry. The possibility of a pre-accident control restriction could not be discounted, although the late change of aircraft attitude showed that, had there been a restriction, it cleared itself. The evidence available suggested a loss of aircraft control while in IMC followed by an unsuccessful attempt to recover the aircraft to safe flight. It is possible that the pilot lost control through a lack of skill but this seemed highly unlikely given that he was properly licensed and had just completed an extensive period of supervised training. Incapacitation of the pilot, followed by an attempted recovery by the additional crew member, was a possibility consistent with the evidence and supported by the post-mortem report. Without direct evidence from within the cockpit, it could not be stated unequivocally that the pilot became incapacitated. Likewise, loss of control due to a lack of skill, control restriction or distraction due to flap asymmetry could not be excluded entirely. On the balance of probabilities, however, it was likely that the pilot lost control of the aircraft due to medical incapacitation and the additional crew member was unable to recover the aircraft in the height available."
Three Safety Recommendations were made as follows:
- that the European Aviation Safety Agency require all in‑service and future turbine aircraft with a Maximum Certificated Takeoff Mass of 5,700 kg or less and with a maximum operational passenger seating configuration of between six and nine passengers to be fitted with, as a minimum standard, a Class B Terrain Awareness and Warning System certified to ETSO-C151b. [2016-055]
- that the International Civil Aviation Organisation revise Annex 6 to the Convention on International Civil Aviation, Part 1 (International Commercial Air Transport – Aeroplanes) to upgrade recommendation 6.15.5 [carriage of TAWS on turbine aeroplanes with a Maximum Certificated Takeoff Mass of 5,700 kg or less and authorised to carry more than five but not more than nine passengers] to a standard. [2016-056]
- that the International Civil Aviation Organisation revise Annex 6 to the Convention on International Civil Aviation, Part 2 (International General Aviation – Aeroplanes) to upgrade recommendation 18.104.22.168 [carriage of TAWS on turbine aeroplanes with a Maximum Certificated Takeoff Mass of 5,700 kg or less and authorised to carry more than five but not more than nine passengers] to a standard. [2016-057]
The Final Report of the Investigation was published on 13 October 2016.