Bad weather, human error causes of Adhikari’s chopper crash: Probe panel (Full report)
KATHMANDU, Feb 25: A probe panel formed to investigate into the Air Dynasty helicopter crash, which killed Rabindra Adhikari and six others near Sisne Khola of Pathivara in Taplejung district on Feb 27 last year, has concluded that bad weather and human error were the major causes of the crash.
The report prepared by the four-member Accident Investigation Commission led by Yajna Prasad Gautam states that unfavorable weather condition at Pathibhara area, excess load on front bench seat which contributed for the Center of Gravity to go beyond the limit, the concern of the occupants to escape from that deteriorating weather as early as possible, condensation inside the windshield and icing on the outside of the windshield which reduced outside visibility, insufficient operational oversight from the organization, inadequate pre-flight planning and lack of consideration on individual load while preparing load and trim sheet are the contribution factors of the crash.
The VIP flight was given approval to fly on VNKT (Tribhuvan International Airport)-Panchthar-VNKT sector by TIA office on February 27, 2019. Even though the approved flight plan was for Panchthar with ETD of 0230 UTC, the PIC (pilot in command) requested the tower to change the destination to Terathum in VHF (Very High Frequency) indicating VIP on board. The flight was then approved to VNKT-Terathum-VNKT sector. The helicopter departed from VNKT at 0246 UTC (08:31 LT) and arrived Terathum at 0409 UTC (9:54 LT). As per the scheduled plan, the helicopter supposed to fly back to VNKT from Terathum but the helicopter departed from Chuhandada Terathum at 0545 UTC (11:30 LT) and proceeded to Pathibhara without prior approval and landed at approximately 0604 UTC (11:49 LT). Around forty-five minutes later, at 0649 UTC (12:34 LT), the helicopter departed for VNKT and met with a fatal accident within a minute later. The aircraft crashed at an altitude of 10350 ft. coordinated at N27025’42”, E087045’59”.
“At the time of accident, the weather around the crash site was low ceiling with cloud base from ground level, gusting strong wind with light to moderate snowfall, sky and mountain ridges invisible according to nearby eyewitnesses,” the report states.
The report has found that the flight to Terhathum was arranged at very short notice and the VIP passenger travel was not notified to the flight operation till the time of boarding.
“While the flight plan was submitted to the ATS Reporting Office, the destination was Panchthar. But while on start-up PIC changed the destination to Terhathum through RT.”
“Since the helicopter was initially dispatched for Kathmandu–Tehrathum-Kathmandu, it looks he easily accepted the request of additional sector flight made by the passenger on board even in the bad weather. PIC may have additional excitement to satisfy the interest of high level passengers onboard. Without analyzing the aircraft limitation, weather factor and fuel status etc. PIC took off from Pathibhara.”
The fuel planning of the fight was also not appropriate.
“The normal fuel consumption rate of the aircraft was 130 kg per hours. Estimated endurance remaining at the time of accident was for 1 hours and 30 minutes; which could have been insufficient for the helicopter to fly back to Kathmandu. In the adverse weather condition the helicopter may need more fuel than normal to reroute the flights.”
The number of the passengers that would be making the trip was also not confirmed till the last moment of the boarding. The passengers were seemed to be in a hurry. Since the destination was not confirmed the flight dispatcher prepared the load and trim sheet only for the Kathmandu- Panchthar-Kathmandu sector, the report states.
It has been found that the passengers were not weighed individually as per the aircraft flight manual and an average weight of 75 kg per passenger was taken for C of G calculations.
The actual C of G of the helicopter was beyond the prescribed limits when taking off from Kathmandu. While taking off from Pathibhara the possibility of shifting C of G further forward was more likely.
“One of the limitation of helicopter as per flight manual is cabin compartment load limitation that is 154 Kg in front two passenger seat. Supplement 21 of flight Manual shows that seven seat configuration is allowed but presence of seven seat and only pilot cause significant change in the C of G position. So, each configuration must be checked properly. The limitation on C of G was overlooked by both the dispatcher and PIC in practical. So exceeding the limitation of the helicopter during flight operation could be considered as one of the contributing factor of the accident,” the report states.
The report also concludes that the pilot suffering from euphoria is the probable cause of the accident.
“The PIC, who was possibly affected with euphoria (initial phase of hypoxia) immediately after take-off from the Pathibhara helipad in unfavorable weather encountered strong gusting wind along with snowfall which led him to inadvertently enter into IMC conditions, lost his situational awareness and positive control of helicopter which ultimately led to the accident and ended with the tragic crash, the report states.
The Commission has also made 13 safety recommendations to the concerned agencies for the enhancement of safety and to prevent such accidents in the future.
See full report below: