What happened
On 19 January 2021, a Boeing 737-40 116,700 lb cargo aircraft, registration G-JMCY, was performing a night approach to Runway 26 at Exeter Airport. The flight was part of a scheduled cargo operation between Exeter and East Midlands.
As the aircraft descended on the ILS approach, the rate of descent began to fluctuate significantly. Although the crew had declared the approach stable at 500 ft radio altitude, the rate of descent soon exceeded the permitted limits. The aircraft experienced several high-sink-rate excursions, triggering multiple GPWS "SINK RATE" alerts. During the final stages of the descent, the pilot flying reduced thrust and adjusted pitch, which led to the aircraft dropping onto the runway. The resulting hard landing caused significant structural damage, including a distorted fuselage, a bent inboard driveshaft, and a broken flap gearbox. There were no injuries to the two crew members on board.
The investigation
The AAIB examined flight data from the FDR, CVR, and TAWS, alongside airfield wind data and aircraft manufacturer assessments. The investigation established that the aircraft's pitch attitude varied significantly between 5° nose up and 6° nose down during the final 500 ft, suggesting over-controlling or excessive corrections.
Investigators also reviewed the operator's operating manuals and the crew's previous training records. It was noted that while the aircraft manufacturer's manual required a go-around if stability was not maintained, the operator's manual lacked specific instructions for an approach becoming unstable after the initial 500 ft stability gate. Furthermore, the investigation identified that the operator lacked a robust mechanism to track individual pilot performance trends during recurrent training checks.
Findings
- The primary cause of the hard landing was the decision to continue the approach after it had become unstable.
- The crew failed to initiate a go-around despite multiple GPWS alerts and increasing rates of descent.
- The commander likely deferred to the co-pilot's ability to correct the flight path, failing to take control or command a go-around.
- Discrepancies between the manufacturer's flight crew training manual and the operator's operations manual regarding stability requirements contributed to the error.
- The aircraft's landing rate reached approximately 24 ft/second, which was significantly higher than the stable approach parameters.