Executive summary
On Monday 14 September 1998 at about 1152 hours, ZK-DKL, a Cessna 177B Cardinal on an air transport scenic flight across the Mount Cook region struck a snow-covered mountain face 11 km north-east of Mount Cook. The pilot and two passengers died as a result of the impact.
The aircraft probably encountered a strong laminar downdraught before entering a thin cloud layer before impact. Although ample escape options were available to the pilot to turn ZK-DKL away from the rising terrain and cloud ahead, he did not make a timely decision to do so. Why the pilot did not make a timely turn away could not be explained.
The pilot might have persevered for too long expecting to encounter an updraught, or some distraction could have diverted the pilot's attention from the safe operation of the aircraft, which prevented him from recognising that ZK-DKL was descending quickly toward the cloud layer and mountainous terrain until shortly before the aircraft entered cloud. Alternatively, the pilot might have been unaware of or misjudged the intensity of any downdraught ZK-DKL encountered.
The pilot may have believed he had crossed the Main Divide to the west; consequently once ZK-DKL entered the cloud he most likely elected to go on in order to break out of the cloud, as he knew the conditions were clear ahead on the west coast.
The cause of the accident was not established.
No safety deficiencies were identified requiring recommendations.