Investigators have detailed how a bungled go-around resulted in a Boeing 737-300’s striking the runway as its gear retracted, causing substantial damage before the jet became airborne again.
The Avia Traffic aircraft had been descending towards the Kyrgyz city of Osh in poor visibility – below minimum conditions for a Category I instrument approach to runway 12 – when the crew opted to execute a go-around.
Russia’s Interstate Aviation Committee says the go-around should have been executed at a height of 60m but was belatedly initiated at 45m.
“The decision to go around was made correctly,” it says. “But the action commenced with some delay.”
While the crew still had sufficient margin to perform the go-around, the inquiry says, the pilots mishandled the procedure.
The captain applied go-around thrust, and called for flap retraction, but responded to the natural pitch-up motion of the aircraft by pushing forward on the yoke.
Investigators indicate that the captain could have been experiencing somatogravic illusion – a false impression of sharp nose-up attitude – possibly resulting from fatigue.
“It led to a breach of the missed approach profile,” says the inquiry into the 22 November 2015 accident. It adds that the first officer’s “passive” behaviour meant the captain’s errors went uncorrected.
As a result the aircraft, which was just 38m above the runway and travelling at 146kt, continued to descend instead of climbing away.
The crew failed to communicate adequately with one another and prematurely initiated landing-gear retraction before verifying that the 737 had achieved positive climb.
Audible “don’t sink” warnings started sounding but although the descent rate, in the last 2s of flight, was reduced from about 1,570ft/min to 790ft/min, the aircraft struck the runway at 178kt some 226m beyond the threshold.
The landing-gear had been only 4s into its 9s retraction cycle and the undercarriage was still in an intermediate position when the impact occurred.
After the runway contact the aircraft became airborne and climbed away. While the crew chose to divert to Bishkek – their point of departure – the impact had damaged the right-hand CFM International CFM56 engine and hydraulic systems, and the pilots opted instead to attempt an emergency landing in Osh despite the poor weather.
The 737 suffered an undercarriage collapse during the Osh landing and sustained further heavy damage as it overran the runway.
But the inquiry credits the captain with “skilfully” executing the landing, given poor weather and the state of the aircraft – which was operating on a single engine and with flaps at 15°. There were no fatalities among the 159 occupants.
The aircraft (EX-37005) had originally been conducting a Krasnoyark-Osh service but had previously diverted to Bishkek as a result of the weather.
Its crew had opted to proceed to Osh but, the inquiry says, the relatively short duration of the flight, less than 2h, meant the pilots were not required to consider weather trends for the destination, and could choose to fly based on actual conditions at the time.