Kathmandu: It has been revealed that there was no power from the engine of the Yeti Airline aircraft that crashed in Pokhara a month ago.
The preliminary investigation of the government, released on Wednesday, shows that the pilot who was flying the plane mentioned twice that there was no power coming from both the engines.
After analyzing the flight data recorder and cockpit voice recorder, the commission has found that the feathering of both propellers during the landing was the main cause of the accident.
The fatal accident, biggest in the history of Nepal, killed all 72 people, including four crew members, on board.
In the initial 14-page report, the commission has also revealed the details of the conversation between pilot [Pilot Flying] and co-pilot [Pilot Monitoring] a few minutes earlier of the accident.
On the day, captain Anju Khatiwada was sitting in the main command seat on the left side as a Pilot Flying while senior captain Kamal KC was performing the role of Pilot Monitoring.
The investigation report mentions that that the over control of the aircraft was handed over to the Pilot Monitoring [instructer pilot Kamal KC] just a few seconds prior to the crash.
The ATR 72-212A was operating scheduled flights between Tribhuvan International Airport and Pokhara Regional International Airport. The same crew operated two sectors between Kathmandu and Pokhara and Pokhara and Kathmandu earlier in the day.
The flight was operated by two captains, one captain was in the process of obtaining aerodrome familiarization for operating into Pokhara while the other captain being the instructor pilot. The Captain being familiarized, who was occupying the left hand seat, was the Pilot Flying (PF) and the instructor pilot, occupying the right hand seat, was the Pilot Monitoring (PM).
The take-off, climb, cruise and descent to Pokhara was normal. “During the first contact with Pokhara tower the Air Traffic Controller (ATC) assigned runway 30 to land. But during the later phases of flight, the crew requested and received clearance from ATC to land on Runway 12,” according to the report.
Here is a brief timeline of the aircraft’s final moments:
10:51:36: the aircraft descended (from 6,500 feet at five miles away from Pokhara and joined the downwind track for Runway 12 to the north of the runway. The aircraft was visually identified by ATC during the approach.
10:56:12: The pilots extended the flaps to the 15 degrees position and selected the landing gear lever to the down position. The take-off (TO) setting was selected on the power management panel.”
10:56:27: the pilot (pilot flying) disengaged the Autopilot System (AP) at an altitude of 721 feet Above Ground Level (AGL).
10:56:50: when the radio altitude callout for five hundred feet 3 was annunciated, another “click” sound was heard4. The aircraft reached a maximum bank angle of 30 degrees at this altitude. The recorded the propeller rotation speed (Np) and the torque (Tq) data remained invalid. The yaw damper disconnected four seconds later. The PF consulted the PM on whether to continue the left turn and the PM replied to continue the turn.”
10:56:50: when the radio altitude callout for five hundred feet3 was annunciated, another “click” sound was heard4. The aircraft reached a maximum bank angle of 30 degrees at this altitude. The recorded Np and Tq data remained invalid. The yaw damper disconnected four seconds later. The PF consulted the PM on whether to continue the left turn and the PM replied to continue the turn. Subsequently, the PF asked the PM on whether to continue descend and the PM responded it was not necessary and instructed to apply a little power.
10:56:54: another click was heard, followed by the flaps surface movement to the 30 degrees position.
10:57:07: The ATC gave clearance for landing. The PF mentioned twice that there was no power coming from the engines.
10:57:11: the power levers were advanced first to 62 degrees then to the maximum power position. It was followed by a “click” sound at 10:57:16. One second after the “click” sound, the aircraft was at the initiation of its last turn at 368 feet AGL, the high pressure turbine speed (Nh) of both engines increased from 73% to 77%.
10:57:18: the PF handed over control of the aircraft to the PM.
10:57:20: the PM (who was previously the PF) repeated again that there was no power from the engines.
10:57:24: when the aircraft was at 311 feet AGL, the stick shaker was activated warning the crew that the aircraft Angle of Attack (AoA) increased up to the stick shaker threshold.
10:57:26: a second sequence of stick shaker warning was activated when the aircraft banked towards the left abruptly. Thereafter, the radio altitude alert for two hundred feet was annunciated, and the cricket sound and stick shaker ceased.
10:57:32: sound of impact was heard in the CVR.
10:57:33: The FDR stopped recording
10:57:35 The CVR stopped recording