What happened
On 24 March 2005, a DHC-8-3 and registration G-NVSB was conducting a passenger flight from Manchester to the Isle of Man. While performing a visual approach to Runway 08 at Isle of Man (Ronaldsway) Airport, the aircraft descended significantly below the expected glidepath.
During the approach, the aircraft entered a turn that brought it into close proximity with high ground. This triggered several alerts from the Enhanced Ground Proximity Warning System (EGPWS), including "TERRAIN" and "PULL UP" warnings. The crew's response to these warnings was delayed. Eventually, the commander initiated a go-around maneuver to avoid the terrain. There were no injuries and no damage to the aircraft, though the incident occurred while the aircraft was 5.7 nm west of the airport.
The investigation
The AAIB investigation relied on EGPWS memory data, as the Flight Data Recorder and Cockpit Voice Recorder had been overwritten prior to the investigation. The investigation noted significant discrepancies between the accounts provided by the commander and the co-pilot.
Investigators examined the aircraft's configuration and the crew's adherence to company procedures. The EGPWS data confirmed that the warnings were legitimate and that the aircraft was at a low altitude of approximately 680 ft amsl when the first hard warning occurred. The investigation also reviewed the operator's manual, which required a full energy pull-up maneuver upon receiving a hard warning below the Minimum Safe Altitude, and mandated that a go-around must be initiated immediately if visual reference to the airport is lost.
Findings
- The aircraft was descended at an inappropriate point, placing it well below the intended glidepath.
- The crew's response to the EGPWS warnings was delayed and did not align with company instructions.
- The co-pilot's situational awareness was degraded, partly due to a reliance on DME indications that were not referenced to the runway.
- There were indications of shortcomings in Crew Resource Management (CRM), as the commander did not intervene during the inappropriate descent and the co-pilot did not communicate losing visual contact with the airfield.