A 1969-built, de Havilland Canada DHC-6 Twin Otter 200HG was scheduled to operate four flights on the 16th of November 2017.
After the uneventful completion of the first three sectors, the last sector was scheduled to be flown between Dhoores Water Aerodrome and Malé-Velana International Airport, both in the Maldives.
The aircraft partly sank after losing the floats (Source: twinotterworld.com ©: Maldives AIIC)
After completing the pre-flight procedures the aircraft cast off from the floating platform at Dhoores Water Aerodrome with a crew of three (2 pilots and a cabin crew member) and 12 passengers. The co-pilot assumed the role of pilot flying for this sector. As the sea conditions were bad the crew discussed the best take-off path, considering the swell patterns. This led them to a take-off path nearer to the island. Once the required checklists were completed both the Pratt & Whitney Canada PT6A-27 and both the Hartzell (HC-B3TN-3DY), three-bladed, constant speed, propellers were set to the take-off setting. As the aircraft accelerated the occupants felt a small bump as the aircraft struck a swell. The take-off was continued and a second swell hit the right float a short while later, causing it to be detached from the aircraft. The aircraft bounced and hit a third swell, this caused the left float to partially be detached from the aircraft. During all encounters with the swells, the crew adjusted the speed on every bounce by lowering the nose primarily to ride the swells and avoid heavy impact on the
next swell. With both floats (partially) detached both propellers hit the detached floats causing a lust of thrust, bringing the aircraft to a stop.
The aircraft partly sank after losing the floats (Source: twinotterworld.com ©: Maldives AIIC)
The Pilot in Command shut down both engines and ordered an evacuation, which the cabin crew had already initiated. With the aid of the co-pilot, who opened the left cabin emergency door, all passengers evacuated the aircraft. Boats picked up the passengers and crew and brought them to the resort.
Damage to the aircraft was substantial;
Both floats detached from the aircraft and damaged by the propellers
Severe damage to the aircraft nose section, partly detaching during aircraft recovery
Internal equipment sustained water damage when the forward section of the aircraft was submerged in water
Both propellors damaged
Damage to the wing and engine cowlings.
The Accident Investigation Coordinating Committee of the Maldives (AIIC) investigated the accident. On the 29th of May 2019, they released their comprehensive investigation report.
They identified the following causes;
The take-off attempt was made in bad weather, not in the most appropriate direction and with unusually longer swell distances.
The aircraft was recovered and on the 11th of October 2019, a test flight was flown after it was repaired in Switzerland. Late November 2019 it was ferried back to Maldives where it resumed operations. The AIIC report, which served as the source for this blog can be accessed by clicking on the .pdf file below;
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