What happened
On the night of 11 June 1997, a Beechcraft BE58 Baron, registration ZK-KVL, disappeared from radar during a scheduled night freight flight from Palmerston North to Christchurch. The aircraft, operated by United Aviation, was climbing through 10,000 feet when it began to deviate from its flight path. Shortly after, the aircraft entered a steep, high-speed spiral dive, descending at a rate exceeding 8,000 feet per minute. The wreckage was discovered the following morning in the Tararua Ranges, 21 km south-east of Paraparaumu, where the aircraft had struck a heavily wooded slope. The pilot was killed upon impact.
The investigation
Investigators examined the flight history, aircraft maintenance, and environmental conditions leading up to the impact. The investigation established that the pilot had requested a climb to 10,000 feet shortly before the aircraft's flight path became erratic. Analysis of the wreckage and flight data indicated the aircraft hit the terrain in a nose-down, right-hand spiraling attitude. The investigation also looked into the operational environment of the operator, noting a history of audit non-compliances and the lack of recent meteorological information provided to the pilot during the critical midnight to 0500-hour window.
Findings
Several critical factors contributed to the loss of the aircraft:
- The aircraft likely encountered severe in-flight icing while passing through a convective cell at 10,000 feet, which led to a loss of control.
- An ingress of carbon monoxide into the cockpit likely impaired the pilot's mental capacity and situational awareness.
- The pilot's flight planning was inadequate, as it failed to minimize exposure to known icing conditions.
- There was a lack of appropriate safety culture within the operating company, characterized by a flawed operational environment.
- The pilot did not receive updated route weather information from MetService during the flight period.
Safety action
Following the accident, the investigation highlighted significant safety issues regarding the oversight of the operator. The performance of the Civil Aviation Authority's audits and subsequent supervision was critically examined, particularly regarding the management of identified non-compliances within the airline's operations.