Description

On 30 March 2009, a Fairchild SA227 Metroliner III was being operated by Airwork (NZ) on a public transport air ambulance positioning flight to New Plymouth at night with the medical team on board. The visual approach at destination was rushed and unstable with the distraction of a minor propeller speed malfunction and with un-actioned GPWS/TAWS warnings caused by excessive sink and terrain closure rates. After a hard touchdown close to the beginning of the runway, directional control was lost and the aircraft left the runway to the side before continuing parallel to it for the rest of the landing roll. There was no damage to the aircraft or injury to the occupants but minor damage occurred to runway lighting fixtures.

Investigation

The investigation noted the visual approach to New Plymouth which was the origin of the occurrence was not authorised under Operator procedures. It further noted that the runway excursion occurred because the PF was not in full control of the aircraft during the final approach and landing. The approach had been rushed and was interrupted first by an engine RPM anomaly and secondly by a GPWS warning caused by the rushed approach. Although the airspeed was decreasing quickly on the final approach, the PF decided not to increase power, because he had difficulty controlling the aircraft, which he attributed to the RPM anomaly. He judged it preferable to continue with the landing rather than to go-around with a possible controllability problem.