Investigation Summary
The accident occurred at approximately 19:26 UTC during a private flight from Gillingham Hall to Rostrevor via Coventry. The crash site was located at coordinates 52.47778 N, 1.54389 E (Grid Reference TM407925). The departure was delayed by approximately 50 minutes, during which time dense fog developed with visibility reported in the tens of meters. Despite the poor conditions, the commander briefed a vertical departure. Flight data showed the helicopter climbed to a peak radio altitude of 125 feet AGL as it transitioned to forward flight. However, the aircraft then pitched progressively nose-down, reaching 35 degrees nose-down just before impact. The Cockpit Voice Recorder (CVR) captured the co-pilot making two verbal prompts regarding the pitch attitude to the commander, who was the pilot flying, in the final seconds. Although full collective was applied at the end, the helicopter struck the ground at a high rate of descent (2,400 feet per minute). The AAIB noted that while such a departure would have been prohibited at a licensed aerodrome, it was permissible under the regulations for private sites at the time.
Final Conclusions
The AAIB final report, published on 8 October 2015, concluded that the cause of the accident was pilot error resulting from spatial disorientation due to somatogravic illusion. Contributing factors included the lack of formal training for the pilots in two-pilot procedures, the absence of standardized checklists for the operation, and the limited use of the automatic flight control system (AFCS) during the departure. The investigation found no evidence of technical malfunction or mechanical failure. The AAIB issued two safety recommendations to EASA regarding the certification definition and testing of Vmini (Minimum Instrument Speed) to ensure it accounts for the pilot's ability to maintain control without external visual cues.
Video Analysis
EHEST - Decision Making — A safety video produced by the European Helicopter Safety Team (EHEST) regarding pilot decision-making, referenced by aviation safety analysts in the context of the G-LBAL accident.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Systems & Failure Modes
Automatic Flight Control System (AFCS)
The investigation noted that the limited use of the AFCS during the departure may have contributed to the pilot's inability to maintain a safe flight path in the absence of visual cues.
Radio Altimeter
Recorded data from the radio altimeter showed the aircraft reached a maximum height of 125 feet before descending into the ground.
Interesting Facts
- 01The flight was a private operation which allowed for lower weather minima than commercial flights.
- 02Dense fog was present at the time of takeoff, with visibility estimated at tens of meters.
- 03The commander was the pilot flying and the co-pilot was the pilot monitoring.
- 04No technical malfunctions or mechanical failures were identified by the AAIB.
- 05The aircraft was equipped with a Cockpit Voice Recorder and Flight Data Recorder, both of which were recovered.
- 06The aircraft's manufacturer serial number (MSN) was 31421.
Safety Actions & Advisories
CAA Safety Notice SN-2016/001
Source ↗The UK CAA issued guidance on aerodrome operating minima for private helicopter flights departing IFR from aerodromes not equipped for instrument departures.
IFR Flying Review
Source ↗The CAA initiated a review of IFR flying outside controlled airspace following this and other helicopter accidents.
CAA Safety Notice SN-2017/003
Source ↗The UK CAA issued a revised Safety Notice regarding Helicopter Operations Flight Planning and Safe Flight Execution that specifically references the lessons learned from the G-LBAL accident.
Known Controversies & Unanswered Questions
CVR Disclosure Dispute
Reference ↗During the inquest, the Coroner demanded the release of CVR recordings and fined the AAIB Chief Inspector for non-compliance. The High Court later overturned the fines, ruling that such protected material remains confidential to protect the integrity of future safety investigations.