With 22 people (2 pilots and 20 parachutists) on board, an Antonov AN-28 was getting ready for its seventh flight of the day on this day in 2004. The aircraft had been refuelled after the previous six flights were completed in good weather conditions.
The aircraft wreckage after the accident (© AIBN)
The weather at Østre Æra Airport (Norway) was recorded as;
Wind - 360º 8-10 knots
Visibility - >10 km
Clouds - Scattered at 3000 feet - Local cumulonimbus activity in the area
Temperature - 16ºC
Dewpoint - 8ºC
QNH - 1010 hPa
At 13.05 lt (local time) the flight was cleared by ATC to climb to 15.000 feet (~4500 meters) for the first half of the parachutist to be dropped above the airfield while flying a northerly course over the airfield. Followed by the second half to be dropped on a southerly course over the airfield. During the flight, a large cumulonimbus cloud (CB) with rain approached the airfield from the north. For the second group of parachutists to be dropped over the airfield (the dropzone for parachutists is overhead the runway) the aircraft had to get close to the cumulonimbus cloud. This was done only with visual reference to the cloud as the aircraft was not equipped with weather radar. The last parachutists to leave the aircraft was a tandem jump, within seconds of leaving the aircraft they were covered in ice, indicating lots of moisture in the air and low temperatures. The ice thawed once they reached lower altitudes.
The aircraft the right way up (Source abpic.co.uk © Unknown)
At the time the last parachutists left the aircraft, it was close to the CB cloud at a low airspeed in moderate turbulence. To avoid getting closer to the cloud and to return to Østre Æra Airport the commander (pilot flying - PF) initiated a sudden 90º turn to the left while reducing engine power to idle.
During the turn, the co-pilot (pilot not flying - PNF) observed ice built up on the cockpit windows and activated the aircraft's anti-ice systems. He did this without informing the PF. A few seconds later, both engines stopped and the propellors automatically feathered. The PF immediately ordered the PNF to attempt restarting the engines using the available checklists. However, the engines would not restart. The only option (the 600 x 100 meter runway is surrounded by dense forest) was an engine-off emergency landing at Østre Æra Airport. With both engines failed the hydraulic system was not available to lower the flaps, resulting in a (relatively) high approach speed of 160-180 km/h (86 - 97 knots). An additional complication were the last 10 parachutists aiming for a landing adjacent to the runway.
After flying a southerly downwind the PF turned the aircraft left to finals on runway 01. The touchdown was approximately halfway down the runway at a speed of ~165 km/h (~89 knots), although wheel brakes were applied the PF realised that the aircraft could not be stopped on the runway. Knowing there was rough terrain at the end of the runway the pilot lifted the aircraft off the runway and steered the aircraft to the right. It cleared a 2.5 meter ( ~8 feet) high embankment and flew (in ground effect) for ~250 meters (~820 feet) before touching down in a marshy area north of the airfield. After a groundroll of about 60 meters (~200 feet), the nosewheel hit a ditch, flipping the aircraft over. It came to rest upside down with the nose pointing towards the runway.
Cockpit with floor pushed up and the nose wheel penetrating through the floor. (© AIBN) Both pilots received minor injuries and were able to exit the aircraft via the cargo door opening (the door had been removed for the parachute jumps) the aircraft was damaged beyond repair and written off. The accident was reported to, and investigated by the AIBN (Accident Investigation Board Norway) who published their report on the accident in June 2009.
In short, the AIBN concluded in their report that;
The PF accessed the weather as sufficient for the flight.
With anti-ice switched on and the engines at idle the operational range of the engines was exceeded.
Both engines flamed out and the propellors automatically feathered
The aircraft was operated at an altitude of 15.000 feet, without supplemental oxygen for the crew, possibly exposing the crew to oxygen deficiency (max. operating altitude 13,500 feet for parachutist jumping)
NO checklist existed for the situation
The crew was not trained for the situation
Engine starts failed as the propellor levers were left in the forward position
The AIBN believes that the crew after having entered this difficult situation, carried out a satisfactory emergency landing under very demanding conditions.
The full AIBN report with extensive conclusions and a safety recommendation is available for the readers' reference by clicking on the .pdf file below;