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Last updated: 20 May 2019
Statuts:Enquête Officielle
Date:samedi 27 mai 2017
Heure:14:04
Type/Sous-type:Silhouette image of generic L410 model; specific model in this crash may look slightly different
Let L-410UVP-E20
Compagnie:Summit Air
Immatriculation: 9N-AKY
Numéro de série: 2917
Année de Fabrication: 2014
Heures de vol:2550
Cycles:5467
Moteurs: 2 General Electric H80-200
Equipage:victimes: 2 / à bord: 3
Passagers:victimes: 0 / à bord: 0
Total:victimes: 2 / à bord: 3
Dégats de l'appareil: Détruit
Conséquences: Written off (damaged beyond repair)
Lieu de l'accident:Lukla-Tenzing-Hillary Airport (LUA) (   Népal)
Élévation des lieux de l'accident: 2682 m (8799 feet) amsl
Phase de vol: En approche (APR)
Nature:Cargo
Aéroport de départ:Kathmandu-Tribhuvan Airport (KTM/VNKT), Népal
Aéroport de destination:Lukla-Tenzing-Hillary Airport (LUA/VNLK), Népal
Numéro de vol:409
Détails:
A Let L-410UVP-E20 operated by Summit Air (formerly known as Goma Air) was destroyed in an accident when it attempted to land on runway 06 at Lukla-Tenzing-Hillary Airport in Nepal. The aircraft operated on a cargo charter flight with 1680 kg cargo on board. It took off from Kathmandu at 07:44 UTC at flight 409, bound for Lukla.
It was the 5th flight of the aircraft to Lukla and with the same set of crew. Lukla weather was cloudy, but visibility and ceiling was reported to be fine after an hour of heavy rain. On first contact flight 409 reported abeam Rumjatar descending out of 11300 ft at 08:10 UTC. Lukla Tower provided the latest weather at the airport, as well as enroute weather relayed by 9N-AGU, an AS350 helicopter that had departed Lukla for Kathmandu. Almost 4 minutes after the first contact, Tower informed flight 409 about the deteriorating weather. The right base leg was covered by lifting fog though there was no rain and the final approach area was still visible.
Weather deteriorated further and Tower regularly updated the flight crew. About 30 seconds after flight 409 reported entering valley, Lukla Tower again informed about the latest status of the further deteriorating weather. Flight 409 then informed that they would come up to Bhatkeko Daada and then decide. The pilot also informed they could see some bright spots.
While continuing approach, both cockpit crew sighted the runway at 9100 ft. That was 64 seconds before the impact. While continuing approach the aircraft deviated to the right by almost 15 degrees and erroneously descended too low to 8500 ft whereas threshold height is 8900 ft (on Kathmandu QNH, whereas per AIP it is 9200 ft).
The flight crew attempted to climb and reach the threshold in a landing configuration. The aircraft pitched up to over 25°, the airspeed dropped and the aircraft stalled. Subsequently its left wing first hit a small tree and then impacted the sloping terrain 130 feet short of the runway.
The captain and copilot both sustained fatal injuries.

Probable Cause:

Probable Cause:
The Commission concludes that the probable cause of this accident was aircraft stall as a result of excessive drag created by sudden increase in angle of attack of the aircraft supplemented by low speed (below Vref) in an attempt to initiate immediate climb on a landing configuration (full flap and landing gear down) warranted by the critical situation of the final phase of flight.

The contributing factors for the accident are:
a. Critical terrain and rapidly deteriorating weather condition.
b. Pilot's loss of situational awareness
c. Improper pilot response to stall warning including failure to advance power lever to maximum at appropriate time.
d. Voilation of SOP by the ATS and Pilot as well.

Accident investigation:
cover
Investigating agency: AAIC Nepal
Status: Investigation completed
Duration: 11 months
Accident number: Final report
Download report: Final report

Sources:
» Kathmandu Post
» Hemant Arjyal
» My Republica
» The Himalayan Times


Opérations de secours

Nepal AAIC issued 20 Safety Recommendations

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Photos

photo of Let-L-410UVP-E20-9N-AKY
accident date: 27-05-2017
type: Let L-410UVP-E20
registration: 9N-AKY
 

Video, social media

Plan
Ce plan montre l'aéroport de départ ainsi que la supposée destination du vol. La ligne fixe reliant les deux aéroports n'est pas le plan de vol exact.
La distance entre Kathmandu-Tribhuvan Airport et Lukla-Tenzing-Hillary Airport est de 134 km (84 miles).
Accident location: Approximate; accuracy within a few kilometers.

Les informations ci-dessus ne représentent pas l'opinion de la 'Flight Safety Foundation' ou de 'Aviation Safety Network' sur les causes de l'accident. Ces informations prélimimaires sont basées sur les faits tel qu'ils sont connus à ce jour.
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