What happened
On 2 November 2015, a WK unmanned aircraft, registration WK006, crashed during its recovery phase at Bascombe Down. Following two aborted approaches due to fog, the crew selected a manual override (MO) mode. This decision removed critical safety protections intended to manage the aircraft's approach in adverse conditions. During the final approach, as the aircraft encountered fog at the Connect Point, laser altimeter readings dropped below one metre. This caused the Vehicle Management System Controller (VMSC) to open the Ground Touch identification window while the aircraft was still at 360 ft. Subsequent manoeuvres to capture the glidepath resulted in an acceleration and pitch rate that triggered the 'Ground Touch' logic, falsely declaring the aircraft had landed. Consequently, the V-tail deployed prematurely, causing the aircraft to crash in a 35-degree dive.
The investigation
The investigation examined the technical, environmental, and organisational factors surrounding the loss of WK006. The Panel investigated the meteorological conditions, noting that while the crew followed available instructions, the official documentation—including the Release-to-Service (RtS) and Flight Reference Cards (FRCs)—contained no formal weather limitations regarding cloud or visibility during recovery. Furthermore, the investigation scrutinized the competency of the supervisory chain within 1 ISR Bde and 43 Bty RA. It was established that there was a significant lack of appropriately experienced personnel in key roles; notably, no commissioned officers in the relevant units were qualified on type at the time of the accident. The Panel also reviewed previous safety advice issued following the WK031 accident, finding that software modifications to address VMSC vulnerabilities had not been effectively implemented.
Findings
- The premature selection of MO was a critical factor, as it bypassed safety measures designed to protect the aircraft during recovery.
- There was a significant absence of formal weather limitations in the aircraft's technical documentation, leading to expectations that exceeded the platform's true capabilities.
- A lack of aviation governance and 'air-mindedness' was evident, characterized by inadequate flying supervision and a failure to maintain accurate training and currency records.
- The Flying Supervisor was not qualified on type and could not provide effective oversight during the flight.
- Software vulnerabilities in the VMSC allowed for the erroneous activation of landing logic under specific pitch and altitude conditions.