What happened
On 14 October 2019, a Sikorsky S-92A, registration G-LAWX, was conducting a private flight to a landing site in the northern Cotswolds. The crew, consisting of two pilots, was tasked with transporting nine passengers from Birmingham Airport to the landing site. As sunset approached, the pilots attempted to complete the flight in daylight, despite deteriorating weather conditions and a cloud base of approximately 800 ft agl.
During the approach, the pilots encountered rising terrain and low visibility. The helicopter's Terrain Awareness and Warning System (HTAWS) issued multiple alerts, including 'caution terrain' and 'warning terrain.' Despite these warnings, the aircraft descended to within 28 ft of the ground near a house. The crew initiated an emergency climb, which resulted in a significant engine over-torque of 131% and a 'low rotor' warning. Following this, the crew performed a second approach at night. While the approach was initially unstable, the aircraft eventually landed at the site without damage or injuries to the 9 passengers or the crew.
The investigation
The AAIB investigation examined the flight planning, the crew's use of onboard technology, and the decision-making process leading up to the incident. Investigators reviewed cockpit voice recordings, which revealed confusion regarding flight management system updates and a lack of effective communication regarding altitude alerts. The investigation also looked into the operational pressures facing the crew, specifically the desire to meet a schedule and avoid inconveniencing a client.
Findings
- The primary cause was the loss of situational awareness due to operating in low visibility conditions that were unsuitable for Visual Flight Rules (VFR).
- The crew failed to effectively utilize the available terrain awareness and altitude alert systems.
- Standard operating procedures regarding stabilized approaches, altitude alerts, and crew communication were either not followed or were ineffective.
- Cognitive biases and the pressure to complete the mission in daylight influenced the commander's decision-making.
- There was a conflict of interest involving the commander's role as a customer-facing director, which created tension with his safety obligations as the pilot in command.
Safety action
The AAIB issued several safety recommendations to the Civil Aviation Authority, including the need for clearer guidance on flight phase alleviations, the implementation of Point-in-Space approach procedures, and the assessment of Helicopter Flight Data Monitoring for onshore operations.