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LJ24, vicinity Bornholm Denmark, 2012

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Summary
On 15 September 2012, a Learjet 24 experienced double engine failure in daylight VMC as it positioned visually on base leg at Bornholm and an emergency was declared. The subsequent handling of the aircraft then led to a stall from which recovery was not possible and terrain impact occurred in a standing crop at low forward speed shortly after crossing the coastline. The aircraft was destroyed and both occupants seriously injured. Investigation established that the engines had stopped due to fuel starvation resulting from mismanagement of the fuel system and had been preceded by a low fuel quantity warning.
Event Details
When September 2012
Actual or Potential
Event Type
Human Factors, Loss of Control
Day/Night Day
Flight Conditions VMC
Flight Details
Aircraft LEAR JET Learjet 24
Operator Private
Type of Flight Private
Origin Strausberg Airport
Intended Destination Bornholm Airport
Take off Commenced Yes
Flight Airborne Yes
Flight Completed No
Flight Phase Descent
ENR / APR
Location - Airport
Airport vicinity Bornholm Airport
General
Tag(s) Deficient Crew Knowledge-handling,
Deficient Crew Knowledge-performance
HF
Tag(s) Inappropriate crew response - skills deficiency,
Procedural non compliance
LOC
Tag(s) Loss of Engine Power,
Flight Management Error,
Flight Control Error"Flight Control Error" is not in the list (Airframe Structural Failure, Significant Systems or Systems Control Failure, Degraded flight instrument display, Uncommanded AP disconnect, AP Status Awareness, Non-normal FBW flight control status, Loss of Engine Power, Flight Management Error, Environmental Factors, Bird or Animal Strike, ...) of allowed values for the "LOC" property.,
Collision Damage,
Aerodynamic Stall,
Flight Envelope Protection Activated
EPR
Tag(s) Airport Emergency Medical Response,
RFFS Procedures
Safety Net Mitigations
Malfunction of Relevant Safety Net No
Stall Protection Available but ineffective
Outcome
Damage or injury Yes
Aircraft damage Hull loss
Injuries Most or all occupants
Off Airport Landing Yes
Causal Factor Group(s)
Group(s) Aircraft Operation,
Airport Operation
Safety Recommendation(s)
Group(s) None Made
Investigation Type
Type Independent


Description

On 15 September 2012, a Learjet 24D carrying the previously cancelled registration D-CMMM and on a short private passenger flight from Strausberg, Germany to Bornholm, Denmark and being flown by a single pilot declared an emergency shortly before its intended landing at Bornholm. It crash landed in a field just off the extended centreline of the intended landing runway and approximately half a mile from the threshold. The aircraft was destroyed and both occupants sustained serious injuries. There was no fire.

Investigation

The event was investigated by the Danish AIB. It was noted that the prevailing weather conditions had not been a factor in the lead up to the accident. Flight recorders were not fitted (nor required) but useful data on track and groundspeed could be derived from the Non Volatile Memory Global Positioning System (GPS) readout.

It was established that the standing crop in which the aircraft had crashed was approximately 3 metres tall and considered that this and the low forward speed had both served to render the impact survivable. The crash site is shown below:

LJ24 VC ECRN Resting Place
The aircraft in its final resting place. Reproduced from the Official Report.

Rescue and Fire Fighting Services attendance at the crash site was delayed because TWR personnel were unable to remotely unlock the security gate through which they needed to pass and the vehicles responding did not have the key. They returned to the airport terminal and drove to the accident site via the public highway, not reaching the site until 7 minutes after the crash had occurred. Once there, it took over an hour to release the two occupants. It was noted that the pilot had been wearing only the lap part of the full harness whereas the passenger, who had been sitting in the other pilot seat, had been wearing a full harness.

It was found that, following an earlier annunciation of low fuel quantity in both wing tanks, both engines had stopped with the aircraft fully configured for landing. Shortly thereafter, mishandling had resulted in an airspeed low enough to activate the stall protection system (SPS) at low altitude just as the aircraft had been about to cross the coast (see the diagram below) . It was considered that SPS activation and the nose down stick pusher in particular "might have provoked an instinctively opposite reaction by the pilot" in order to avoid ground impact and that the effect of the conflicting pilot/SPS commands "might have pushed the aircraft into a deeper stalled state" which finally led to the unrecoverable stall and the crash.

LJ24 VC ECRN GPS Track
The track of the aircraft approaching Bornholm - Cleared to land at 'B', declaration of emergency at 'C' and stall/terrain impact from low level at 'D'. Reproduced from the Official Report.

It was established that the reason why both engines had stopped was because the pilot had mismanaged the fuel on board so that the main (wing) tanks ran dry whilst being fed from the wing tanks when there was still fuel remaining in the fuselage tank. It was noted that to allow this fuel to be fed to the engines, which was only possible from the respective wing tanks, the fuel transfer switches would need to have been open, whereas they were found in the closed position. Despite the presence of available fuel, the Investigation considered that "pre flight fuel planning had been inappropriate and inconsistent with" the regulations for the Instrument Flight Rules (IFR) flight plan filed.

It was found that the Aircraft Flight Manual (AFM) for the aircraft type specified a minimum operating crew of two pilots and that it was so certified. It was also found that the aircraft registration was no longer valid, having been cancelled in 2012 on the grounds that no valid airworthiness certificate could be found. Further inquiries established that the most recent airworthiness certification had expired on 31 March 2005. It was also established that there was no record that the aircraft was being maintained by a JAR-145 maintenance or Continuing Airworthiness Management Organisation (CAMO) or subject to any equivalent maintenance programme. However, no evidence of any malfunction which might have been relevant to the finding of fuel starvation was found.

Overall, the Investigation was found to have been "hampered by the lack of valid" aircraft, flight operational and pilot-related documentation. In respect of the pilot, two FAA ATPLs were recovered from the wreckage which bore the same licence number but different holder names - both of which "were inconsistent with the pilot's Iranian identity". It was not possible for the Investigation to determine whether the pilot had held a valid licence issued elsewhere.

It was observed that "there was a mismatch between the actual aircraft operation and the objective of ensuring flight safety by a regulated aviation system". Having noted that the aircraft had made 12 flights during 2012, the Board concluded that "from a systemic point of view….it (was therefore) thought-provoking that a non-registered aircraft was accepted by the regulated aviation system" and, though accepting that this situation had not been found to be directly relevant to accident causation, "considers this finding a flight safety issue, which needs further consideration by EASA".

The formally stated Conclusion of the Investigation was that:

  • Inadequate en route fuel management resulted in fuel starvation of both engines, while the aircraft was flying at low altitude and the airspeed was decreasing.
  • The dual engine flame out and the subsequent aircraft speed control led to an unrecoverable stall and consequently caused the accident.

Safety Action was noted to have been take by the aerodrome operator in respect of the difficulty which RFFS personnel had encountered in reaching the accident site promptly by placing keys to the perimeter security gates in all airport emergency vehicles.

The Final Report was published on 14 August 2014. No Safety Recommendations were issued as a result of the Investigation.

Further Reading