Description

On 16 May 2013, a De Havilland Canada DHC6-300 (9N-ABO) being operated by the Nepal Airlines Corporation on a passenger charter flight from Pokhara to Jomsom in day VMC left the destination runway after a day VMC approach and after a failed attempt to take off again, crashed into a nearby river. Of the 21 occupants, the two pilots and one passenger were seriously injured, 6 other passengers and the cabin attendant sustained minor injuries and 11 other passengers were uninjured. The impact damage to the aircraft was substantial but although fuel was leaking from it, there was no post crash fire.

Investigation

An Investigation was carried out by an Aircraft Accident Investigation Commission constituted by the Government of Nepal, Ministry of Culture, Tourism and Civil Aviation. The 30 minute CVR fitted to the aircraft was recovered and downloaded and good data was obtained.

It was established that that the aircraft and crew had positioned to Pokhara the day before the accident in order to operate up to five Pokhara-Jomsom-Pokhara charter flights planned for 16 May 2013. The accident flight was the outbound leg of the second rotation with the Captain as PF and was expected to take about 20 minutes. The flight made initial contact with Jomsom at the compulsory reporting point 9 miles from the airport when maintaining an altitude of 12,500 feet and was advised that Runway 24 was in use with the surface wind south westerly at 8-12 knots. The Co-pilot accepted the instruction to report downwind for runway 24. Subsequently, with no briefing or discussion between the two pilots about the tail wind which would result, the Captain called and requested Runway 06 instead of Runway 24. The wind speed as previously given was repeated and on hearing the response from the Captain of ”no problem”, the use of Runway 06 was approved.

The pre-landing checklist was completed and in respect of a missed approach, the response of the Captain had been “standard”. Full flap was used and the aircraft touched down - not fully aligned with the runway centreline - some 237 metres past the threshold of the 739 metre-long paved runway (elevation 8976 feet amsl). After rolling for 59 metres the aircraft left the runway to the right onto grass. It continued for a distance of approximately 215 metres at a maximum distance from the edge of the runway of 6 metres before re-entering the runway. Then, without any communication with the Co-pilot about his intention, the Captain "started adding power with the intention of taking off". The accelerating aircraft had insufficient speed to get airborne and overran the end of the runway, breached a barbed-wire fence and gabion wall and finally fell down into the edge of the Kaligandaki river. The aircraft came to a stop with the left wing resting in the middle of the river preventing the aircraft being totally submerged.

Damage to the aircraft included the complete severance of the right wing and complete detachment and destruction of the structure at the front of the aircraft including the cockpit.

The 39 year old Captain was found to have accumulated 8451 flying hours, almost all of them on the DHC6 which he had been flying for 13 years. The 29 year-old Co-pilot had accumulated 1396 flying hours, all but 194 of them on the DHC 6.

The Investigation noted that:

• Jomsom was designated as a STOL airfield but concluded that the approach made had not been in accordance with the applicable procedures with which the Captain had been familiar. In particular, the airspeed on final approach appeared to have been much higher than the 70+/- 5 knots prescribed - in excess of 100 knots.
• The DHC6 AFM contained a limitation of a 10 knots tail wind component for landing but the reported wind speed exceeded that limit.
• Poor CRM had prevailed during the accident sequence.

The Investigation determined that the Probable Cause of the accident was "the inappropriate conduct of the STOL procedure and landing technique carried out by the PIC during landing phase and the attempt to carry out a take off again with insufficient airspeed, no required lifting force and non-availability of required runway length to roll".

In addition, Contributory Factors were determined as "the absence of proper CRM in terms of communication, coordination and briefing between crew members on the intentions and action being taken by the PIC during the pre and post landing phase".

Three Interim Safety Recommendations were issued to the Government of Nepal Ministry of Culture, Tourism and Civil Aviation (MoCTCA) on 24 May 2013 as follows:

• Considering the typical geographical location and nature of wind, arrangements should be made to stop tail-wind landings and take offs whenever the wind speed at Jomsom airport exceeds 5 knots.
• Arrangement should be made to restore the damaged fencing to the east side of the (touchdown) end of runway 24 (at Jomsom airport) as soon as possible.
• Special surveillance should apply to any pilots (who have been) involved in one or more serious incidents or accidents with regard to any corresponding action taken thereon by the CAA of Nepal.

All three of these Recommendations were reported to have been appropriately actioned prior to the completion of the Final Report on the Investigation.

A total of 12 further Safety Recommendations were made at the conclusion of the Investigation as follows:

• that the Government of Nepal, Ministry of Culture, Tourism and Civil Aviation (MoCTCA) should establish an independent and effective aircraft accident investigation mechanism with the provision of adequate resources and functional autonomy to effectively conduct accident investigations and continuously monitor the implementation and compliance-status of remedial safety measures.
• that the MoCTCA should encourage the Nepal CAA and airline operators to take initiatives towards promoting safety culture and best practices as well as producing credible outcomes in the formulation of rules, regulations, requirements and standards and their proper implementation.
• that the Civil Aviation Authority of Nepal (CAAN) should further strengthen its surveillance and monitoring function focusing on critical safety areas including violation of SOP, proper application of CRM, Controlled Flight Into Terrain (CFIT), runway incursions/excursions, approach and landing accident reduction etc. and ensuring (that there is an) effective enforcement mechanism (in place).
• that the CAAN should, in order to undertake proactive safety measures, establish a dedicated committee of relevant professional experts to undertake an in-depth review of the existing STOL field (at Jomson), taking into account the major factors – particularly the runway length and slope, runway layout, runway condition, runway marking, regulated weight, approach, prevailing wind velocities and the presence of obstructions etc. – and ensure( that) corrective action (is taken to counter) risk factors as necessary.
• that the CAAN should encourage the professionals like pilots, engineers, ATC Officers and the general public to report the unsafe practices and establish a database of such (reports) from concerned people and the airline(s) to (be analysed for) identified and (the results used) to take risk mitigation and remedial measures as necessary.
• that the CAAN should strengthen its regulatory capacity by ensuring that ATS and AFIS personnel working at airports should receive customised training which includes STOL airfields, aircraft operating limitations and the relevant provisions of safety regulations applicable at airports.
• that the CAAN should, considering the typical geographical location and nature of wind velocity at Jomson airport, make arrangements to prohibit tail wind landings in the case of a wind speed which exceeds 5 knots.
• that the Nepal Airlines Corporation (NAC) should strengthen training on Crew Resource Management (CRM) focusing attention on the critical phases of flight (take-off, landing and missed approach phases) as identified in the analysis and findings of this report.
• that the NAC should further strengthen its existing mechanism to monitor, investigate and mitigate the risk associated with repetitive defects of particular aircraft at expert level to strengthen flight safety.
• that the NAC should, considering the specific points mentioned in the analysis and findings of this report, develop and maintain procedures for STOL operation which (ensure that) pilots know and apply the rules, regulations and standards and (are capable of) analysing the risk and enhancing safety performance.
• that the NAC should review and update its SOPs to make them compatible with the available facilities and include recommended guidelines for its pilots (particularly in respect of) the take-off, landing and missed approach phases.
• that the NAC should develop qualified professionals as trainers on Safety Management System (SMS) and impart such knowledge to all key personnel, pilots, engineers and relevant ground staff, setting a target date for the full implementation of SMS including an applicable database.

The Final Report was completed on 18 February 2014 and subsequently published.

Related Articles

• Tailwind Operations
• Short Take-Off and Landing (STOL)
• Missed Approach
• Runway Excursion
• Unstabilised Approach: Landing Distance and Final Speed Calculations
• Unstabilised Approach: Vectoring to Runways with Significant Tailwind Component
• Crew Resource Management
• Safety Management System