What happened
On the night of Friday, 8 May 1998, an Air Nelson Metro aircraft, registration ZK-NSJ, was performing a scheduled service as Airlink (RLK) 8611. The flight was traveling from Hokitika to Christchurch when the crew encountered unexpected fog at both the destination and the designated alternate aerodromes. Because the fog was unforecast, the crew was forced to perform four separate ILS approaches. By the time the aircraft was finally able to land at Christchurch, the fuel levels had depleted to a point where no further diversion or alternative flight paths were possible.
The investigation
The investigation focused on the circumstances surrounding the arrival at Christchurch and the lack of available alternatives for the crew. Investigators examined the weather conditions at the time of the flight, noting that the fog at the destination and alternates had not been predicted in the official forecasts. The inquiry also looked into the communication of weather data from ground agents and the operational procedures regarding the release of company agents at departure airports.
Findings
Key findings from the investigation highlighted that unforecast fog was the primary driver of the incident. The crew's ability to continue the flight was severely compromised by the lack of accurate, real-time weather information. Additionally, the investigation identified that the crew had no remaining options for diversion because the fuel reserves had been exhausted by the repeated approach attempts. The inquiry also noted a reliance on issued forecasts without sufficient independent verification of the actual conditions.