Norwegian investigators believe the pilot of an amphibious De Havilland Canada DHC-2 became fixated on an engine check during a flight from Torp Sandefjord to Rytterholmene, and forgot the wheels were still extended before carrying out a water landing.
The aircraft, fitted with both wheels and floats, sharply decelerated as a result of the undercarriage being deployed, and flipped over. While the aircraft sustained damage, the pilot survived uninjured.
Norwegian investigation authority SHK states that the DHC-2 had undergone an engine test at Sandefjord airport, with no problems found, but the pilot was advised to test its performance on the next flight.
After departing the airport for Rytterholmene on 10 June last year the pilot received a ‘check gear’ warning which disappeared when he pulled the gear lever to deploy the wheels.
SHK says the pilot testified to the inquiry that he did not understand why he failed to retract the wheels again, but stated that he had been concern with testing the engine and resolving the ‘check gear’ warning.
En route to Rytterholmene the pilot noticed the aircraft had a slightly lower cruise speed, around 90kt rather than the 95-100kt expected.
“He did not connect this to the fact that he was flying with the wheels out, but instead became convinced that the engine was not delivering normal power, and that there could be something wrong with the engine,” says the inquiry.
While there were checklists available in the cockpit, the pilot relied on a memory mnemonic to prepare for landing, and using mirrors to check wheel position either side, believing the visual check was more reliable than looking at the landing-gear handle or indicator lights.
“He did not register that the wheels were out when he looked in the mirrors and assumed that they were up,” says SHK. The aircraft was fitted with an older, simple gear-warning system but the pilot felt it was prone to issuing unwanted alerts.
SHK credits the pilot with remaining calm as the cockpit filled with water, and waiting until pressure equalised before opening the cockpit door and swimming out.
It points out that a 2023 US study of 183 amphibious aircraft accidents over 2005-20 showed the fatality rate was 34%, higher than the overall average of 20% for small aircraft, and that failure to configure the aircraft properly before landing is one of the factors highlighted.
SHK is recommending that pilots familiarise themselves with the concept of threat and error management, which teaches the recognition and management of potentially risky situations during flight.
