All 72 people — 68 passengers and four crew members — on board the aircraft, registered 9N-ANC and operating flight NYT691, were killed in the crash. Arriving from Kathmandu, the ATR 72, a twin-engine turboprop, was approaching Pokhara’s new airport when it crashed on the Seti river bank.
Here’s what the report says:
The last minutes
Both pilots were of Captain rank. One was on “aerodrome familiarisation to operate into Pokhara”, the other was the ‘instructor pilot’. Before the accident flight, the crew had operated two flights between Kathmandu and Pokhara the same morning. This was their third flight that day, which turned tragic. The Captain on “aerodrome familiarisation” was the Pilot Flying (PF) and occupied the left seat. The instructor pilot, in the right seat, was the Pilot Monitoring (PM).
Initially, the aircraft was cleared to land on Runway 30 by Pokhara ATC. Later, the crew requested to land on Runway 12, which was cleared by the ATC.
10:56:12 (Nepal Local Time)
The crew extended the flaps to 15 degrees position and moved the landing gear lever to down position. Take-off (TO) setting was selected on the power management panel.
The action indicates the crew was configuring the aircraft for landing and possible go-around in case of a missed approach.
10:56:27
The PF disengaged the autopilot at 721 feet altitude and, at 10:56:32, called for “flaps 30”. The PM replied, “Flaps 30 and descending”.
Crucially, according to the report, the flight data recorder (FDR) did not record any flap surface movement. Instead, the propeller rotation speed of both engines decreased simultaneously, so did engine torque, “consistent with both propellers going into the feathered condition”.
Flaps are retractable surfaces on the trailing edge of wings. When extended, they help increase the wing surface and, consequently, ‘lift’ — the upward, aerodynamic force generated by wings that keeps a plane in the air. Flaps are extended before take-off and landing when the aircraft is at a slower speed and requires extra ‘lift’. ‘Flaps 30’ means the PF wanted the extended flaps set at 30 degrees. Extended flaps can be set at different degrees depending on requirement.
During engine failure or an engine shutdown mid-air, a pilot flying an aircraft with variable-pitch propellers changes the pitch / angle of the propeller blades so that they slice the airflow in a more or less parallel motion — like a knife — and not hit the air flatly. This has the effect of reducing the ‘drag’, increasing the gliding distance, and preventing airspeed from decaying below unsafe limits. This is called the ‘feathering’ of propellers. In the ill-fated Yeti Airlines aircraft, the ‘feathered’ engines were no longer producing ‘thrust’ — the power that propels the aircraft forward.
10:56:50
At 500 feet altitude, the aircraft reached a maximum bank angle of 30 degrees. The yaw damper disconnected four seconds later.
Yaw is the movement of an aircraft around its vertical axis. This is achieved by the rudder, the movable — moves left / right — surface mounted on an aircraft’s tail. A yaw damper, also called a stability augmentation system (SAS), when engaged, prevents unnecessary yaw, ensuring a smooth ride and preventing structural stress on the rudder fin if a pilot unintentionally applies too much rudder.
10:57:07
ATC gave clearance for landing. The PF mentioned twice there was no power coming from the engines. At 10:57:11, the power levers were advanced, first to 62 degrees, then to maximum power position. At 368 feet altitude, at the initiation of the last turn, the speed of both engines increased from 73% to 77%.
10:57:18
The PM took over the task of flying from the PF. The PM repeated again that there was no power from the engines. At 10:57:24 at 311 feet altitude, the stick shaker activated.
Stick shaker activation indicates an approaching stall. The plane judders and the pilot’s control column starts shaking, indicating that either the nose has been raised too high or the airspeed is too low, and that the aircraft is about to enter a ‘stall’ — a condition when an aircraft stops flying forward and starts falling out of the sky.
10:57:26
A second stick shaker warning activated as the aircraft banked left abruptly. At 10:57:32, sound of impact was heard in the CVR. The FDR and CVR stopped recording at 10:57:33 and 10:57:35 respectively.
