Nepal Plane Crash | Exact Cause of Yeti Airlines Plane Crash

Nepal Plane Crash:Why did Yeti Airlines ATR-72 aircraft crashed?

Being an aircraft maintenance engineer with a total of 33 years of experience. The following are my views on the Nepal plane crash:

To find the answer why the Yeti Airlines plane crashed is hidden behind another two questions:

1. Why did the ill-fated aircraft abruptly bank to the left?

2. Why was the aircraft configuration in the nose-up position during landing?

The investigators will have to find answers for these two questions. The video footage of the aircraft just before the crash shows that it was abruptly banked to the left. The nose of the aircraft is in an upright position. Another piece of video footage, which was live streamed by one of the passengers, shows that the flap of the left wing was in the mid position and not in the full flap position.

For any aircraft while landing, the flap should be in the fully down position, which increases the surface area to produce more lift at low speed. While landing, the speed of the aircraft must be at a specific range necessary to sustain it in the air. Low speed is required to land properly on the short runway.

There is a checklist and procedures for all aircraft to ensure correct operation during all phases of flight.

Was any Technical Glitch?

Then what happened to this aircraft, and why was the flap not in its full position? Was there any technical problem that restricted pilots from doing so? If so, were they informed of this technical glitch to ATC or discussed in the cockpit or follow the appropriate procedures? This must be recorded in the ATC voice recorder or in the aircraft cockpit voice recorder. The analysis of the CVR will clear everything up.

If No Technical Glitch then what?

If there was no technical glitch, why did the pilot not select full flaps? The aircraft can land at zero flap but at a higher speed and need a longer runway. For the ATR-72 turboprop aircraft, it is an easy task. It can land safely without selecting flaps. The only thing to keep in mind is that aircraft should be flown above the stall range. There was a stall warning system indicators in the cockpit, which indicates and warns about aircraft stall. The investigators will have to find the answer for stall indication as well. Did the stall indicator warn the pilot about stalling?

Why Pilots not Corrected the Problems?

At low speed during landing and aircraft near to ground sharply bank will led to loss of lift and it will create a serious stall condition which led to crash this aircraft. This similar situation led to this fatal crash. The investigators will have to find answers to that question: why did the pilot move the control surfaces to the aircraft bank sharply? No experienced or non-experienced pilot can do this type of silly maneuver. Was there any technical problem with the control system? The asymmetry in the flap system can create similar type of manoeuvres. One flap fully extended and the other partially extended can lead to a similar rolling effect on aircraft and force to crash.

What is the exact cause?

My answer is a technical problem in the flap system or a human error by the pilots. The analysis of the voice recorder and the fight data recorder will reveal everything. Either the pilot had not followed the proper landing checklist or they were not aware of the technical glitch that suddenly occurred just before the crash. Because the aircraft was near the ground, there was very little reaction time to correct the problem. This aircraft crashed due to a sudden stall, which was caused by a wrong procedure or technical glitches in the aircraft control system.