AAIB分析VSR Ventures Learjet坠机事故：不稳定进近与低空失速导致事故

The Aircraft Accident Investigation Bureau (AAIB) has concluded that the September 14, 2023, crash of a VSR Ventures Learjet 45XR at Mumbai airport was caused by the flight crew’s decision to continue an unstabilised approach in marginal weather and inappropriate aircraft handling, which resulted in an aerodynamic stall at low altitude. The aircraft, registered VT-DBL, was operating a non-scheduled passenger flight from Visakhapatnam to Mumbai when it crashed during its approach to Runway 27. All eight occupants, including the two pilots and six other occupants, survived, although they sustained injuries. The aircraft was destroyed in the accident.

According to the investigation report, Mumbai airport was experiencing heavy rain and reduced visibility at the time. The meteorological report at 1130 UTC recorded visibility of 800 metres and a runway visual range (RVR) of 1,000 metres, with heavy rain and winds from 150 degrees at eight knots. The crew initially had the runway lights in sight, but the first officer subsequently reported that they had disappeared. The aircraft was established on the instrument landing system (ILS) approach, with the autopilot engaged in localiser and glide-slope modes. At about 364 feet above ground level, the captain disconnected the autopilot and continued flying manually. The aircraft then began deviating from the runway centreline as the crew struggled to maintain alignment in the prevailing conditions.

The cockpit voice recorder captured the crew’s difficulty in identifying and aligning with the runway during the final approach. At approximately 212 feet above ground level, the aircraft was travelling at 131 knots, but its glide-slope deviation began increasing. At 172 feet, the airspeed had fallen to 127 knots, and the aircraft was above the intended glide path. As the aircraft descended further, the first officer repeatedly called for corrections to the right, while the captain asked whether they had achieved the required alignment. At about 122 feet above ground level, the aircraft was travelling at 118 knots, and the recorded angle of attack had risen significantly. The first officer then called “Go Around” three times. At approximately 112 feet, the airspeed had fallen to 111 knots, and the stick shaker activated alongside the stall warning.

The flight data recorder showed that the crew briefly advanced both thrust levers to approximately full power after the stall warning began. However, the thrust levers were subsequently reduced towards idle as the aircraft continued to lose control. The aircraft’s right-wing-down roll increased rapidly, reaching approximately 53 degrees shortly before impact. At a speed of about 96 knots, the right wing struck the ground first, followed by the fuselage, at an unpaved area near the intersection of Taxiways W and N. The aircraft fractured into sections and skidded across the airport before coming to rest near the intersection of Taxiways U and N, close to stand C80. The Enhanced Ground Proximity Warning System (EGPWS) generated a “Sink Rate, Pull Up” warning as the aircraft approached the ground.

A localised fire broke out following the impact. Mumbai airport’s rescue and firefighting teams responded immediately and extinguished the fire within approximately two minutes. Five passengers were able to evacuate the wreckage unaided, while another passenger was trapped partly beneath the aircraft near the cockpit. Both pilots were trapped in the cockpit and had to be extricated by rescue personnel, who used a crane to lift the wreckage slightly and cut the aircraft’s windshield. The rescue and evacuation operation took approximately one hour. All eight occupants were taken to nearby hospitals. The captain and five passengers were discharged after treatment, while the co-pilot sustained serious spinal and pelvic injuries, required surgery and remained hospitalised for a longer period.

The investigation found no evidence that a technical malfunction contributed to the accident. The aircraft’s airworthiness documents were valid, its weight and centre of gravity were within prescribed limits, and no outstanding technical defects had been reported before the flight. Analysis of the digital engine-control data indicated that both Honeywell engines were operating normally and responding to crew inputs. However, the AAIB identified deficiencies in VSR Ventures’ maintenance record-keeping, internal audits and pilot training documentation. Some technical and airframe logbook entries were incomplete, internal audits had not been conducted diligently, and records showed that certain pilots had not completed all mandatory recurrent-training exercises during the prescribed checking cycle.

The report also identified human-factor and operational considerations. The crew had discussed restrictions on non-scheduled and general aviation operations at Mumbai after 1200 UTC and expressed concern about landing before the restriction took effect. They also sought direct-routing clearances on several occasions during the flight. The AAIB considered the crew’s commitment to landing before the restricted time a contributory factor, alongside heavy rain, degraded visual cues, a tailwind component that varied between eight and 10 knots, inadequate monitoring of declining airspeed and the first officer’s delayed go-around call. Although the investigation examined the separation between the Learjet and a preceding heavy aircraft, it found no evidence of wake-turbulence interaction contributing to the crash.

The AAIB recommended that the Directorate General of Civil Aviation (DGCA) review recurrent-training requirements to include stall recovery in the landing configuration, verify mandatory training records across fixed-wing operators, particularly non-scheduled and general aviation organisations, and issue directions reinforcing the requirement to conduct a go-around whenever an approach is unstable. It also called for stronger internal audits and verification of operator compliance. The investigation’s central finding is that the crew continued an unstable approach in adverse conditions and failed to recover from the resulting low-altitude stall, turning a landing attempt into a survivable but destructive accident.