Nepal DHC6 near Khidim on Feb 16th 2014, aircraft impacted terrain
Last Update: September 16, 2014 / 14:49:38 GMT/Zulu time
Incident Facts
Date of incident
Feb 16, 2014
Classification
Crash
Aircraft Registration
9N-ABB
Aircraft Type
De Havilland DHC-6 Twin Otter
ICAO Type Designator
DHC6
Losing situational awareness on the part of PIC while flying into instrument meteorological weather condition to the extent of Collision with terrain.
The contributing factors to the occurrence are:
- Deteriorated weather associated with western disturbance, unstable in nature and embedded CB.
- Inappropriate and insufficient crew coordination while changing course of action
The captain (49, ATPL, 8,373 hours total, 8,131 on type) was pilot flying assisted by a first officer (28, CPL, 365 hours total) as pilot monitoring.
The aircraft made a planned technical stop in Pokhara to refuel and check weather at Jumla and Siddharthanagar's Bhairahawa Airports, both airports reporting visual meteorological conditions. Jumla had been closed earlier in the day due to being completely in cloud with NIL visibility but now reported 7000 meters visibility, few cloud at 5000 feet and scattered cloud at 7000 feet with calm winds and normal visual meteorological conditions. The crew appeared quite relieved by the weather reports though the enroute weather could not be predicted and the frontal system affecting Nepal promised difficulties including icing expected by the crew. The crew performed normal flight preparations.
Following departure the captain instructed the first officer to plan for a more southerly track to avoid terrain and weather, the first officer programmed the GPS accordingly. Probably while maneouvering around weather 25 minutes into the flight the captain instructed to plan an even more southerly track through the Dang valley, the first officer programmed Dang into the GPS and determined their minimum safe altitude was 8500 feet, then raised concern that they may not have sufficient fuel to reach Jumla.
About one minute prior to impact the captain indicated "I am entering", the NAAIC added "(perhaps inside the cloud)", at the same time the first officer called Bhairahawa Tower to request weather on his own, then transmitted their position as 25nm out of Bhairahawa, during that transmission the captain interrupted and indicated they were diverting to Bhairahawa. Bhairahawa tower inquired about exact position, the first officer radioed "standby". The first officer advised the captain to NOT descend and NOT to turn, however, a few seconds later the aircraft while in a right descending turn contacted and brought down a small tree and impacted terrain at position N27.9119 E83.1156 at 7190 feet MSL, about 30.8nm northwest of Siddharthanagar's Bhairahawa Airport.
The NAAIC analysed that the captain was aware of the possibility of icing and decided to fly a southerly track to avoid weather. The first officer did not properly acknowledge 15 times to the captain however, the NAAIC suspecting because of disagreement with the captain's decisions. The aircraft climbed to 10,500 feet, OAT -6 degrees C, the captain instructed the first officer to monitor for icing, but subsequently descended out of the icing range to 8500 feet and expressed some relief to be out of icing.
Based on the cockpit voice recorder the NAAIC analysed that some words of the captain suggest that he was not aware of their present position. The first officer, assessing the weather conditions, decided to call Bhairahawa Tower on his own without consulting with the captain.
The NAAIC analysed that they were not able to determine when the aircraft left 8500 feet and descended. The cockpit voice recorder ended 35 seconds after the captain announced to divert.
The NAAIC analysed that the captain and first officer had flown several trips together already, they were no strangers to each other. "However, the communication between Captain and Copilot was found not optimal and not in accordance with the rule and practice. Copilot does not acknowledge the captain’s information, or instruction in several occasions. Copilot seemed to be unconcerned and Captain not authoritative, especially when the latter needed feedback and advice from non flying copilot as they were facing problem with weather, and concerned about icing."
The NAAIC analysed that the crew cooperation seemed to be normal during the initial phases of the flight, however deteriorated after the captain descended the aircraft from 10,500 feet to 8,500 feet to leave icing conditions without briefing this intention to the first officer.
The NAAIC analysed in the last few minutes of the flight: "The team work between the crew could not be considered satisfactory. It got worse when PIC Started descending from 8500 to lower level without briefing to Copilot and copilot did not resist the PIC to descend at that particular time. However he was functioning as a pilot monitoring and making PIC aware by expressing ("do not turn" and "do not descend"), but the aircraft has descended down to crash altitude approx. 7190 ft. from 8500 ft." and concluded: "Though the PIC seemed to be confident and showing the quality of leadership in the initial phase of flight, but in later phase his presence of mind about his position and dilemma in actions did not display good leadership."
The NAAIC analysed: "So mechanical failure of airframe and engine system cannot be established and hence this possibility is ruled out." The NAAIC further ruled out lightning strikes or icing could have impaired aircraft or aircraft system performance, the crash site and wreckage do not reveal any indication of any system malfunction prior to impact.
Incident Facts
Date of incident
Feb 16, 2014
Classification
Crash
Aircraft Registration
9N-ABB
Aircraft Type
De Havilland DHC-6 Twin Otter
ICAO Type Designator
DHC6
This article is published under license from Avherald.com. © of text by Avherald.com.
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