Author Topic: MAK Releases Final Report on UTAir 737-800 Runway Overrun at Sochi in Sept 2018  (Read 1776 times)

Offline joeyb747

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Interesting read...

"In Dec 2019 the MAK released their final report, however, without announcing that release on their news page (which caused it to be generally overlooked for a month).

The report concludes the probable causes of the accident were:

The aircraft overrun, destroying and damage by fire were caused by the following factors:

- repeated disregarding of the windshear warnings which when entered a horizontal windshear (changing from the head wind to tail one) at low altitude resulted in landing at distance of 1285 m from the RWY threshold (overrunning the landing zone by 385 m) with the increased IAS and tail wind;

- landing to the runway, when its normative friction coefficient was less than 0.3 that according to the regulations in force, did not allow to land.

The factors contributed the accident:

- the crew violation of the AFM and Operator's OM requirements in regards to the actions required a forecasted or actual wind shear warning;

- use of the automatic flight mode (autopilot, autothrottle) in the flight under the windshear conditions which resulted in the aircraft being unstable (excess thrust) when turning to the manual control;

- lack of prevention measures taken by the Operator when the previous cases of poor crew response to windshear warning were found;

- insufficient crew training in regards to CRM and TEM that did not allow to identify committed mistakes and/or violations in good time;

- the crew members' high psychoemotional state caused by inconsistency between the actual landing conditions and the received training as well as the psychological limit which was determined by the individual psychological constitution of each member;

- insufficient braking both in auto and manual mode during the aircraft rollout caused by the insufficient tyre-to-ground friction aiming to achieve the specified rate of braking. Most probably the insufficient tyre-to-ground friction was caused by the significant amount of water on the RWY surface;

- the aerodrome services' noncompliance of Sochi International Aerodrome Manual requirements related to the RWY after heavy showers inspection which resulted in the crew provision of wrong normative friction coefficients.

In obtaining of the increased overrun speed of about ¡Ö75 kt (¡Ö140 km/h) the later setting of engines into reverse mode was contributed (the engines were set into reverse mode 16 s later than the aircraft landed at distance of about ¡Ö200 m from the runway end)."

"On Nov 6th 2018 the MAK released their preliminary report in Russian reporting the crew had computed their Vref at 147 KIAS and Vapp at 155 KIAS. The crew prepared for an approach to runway 06. While descending through about FL110 towards Sochi the crew was informed another aircraft had just gone around on runway 06, RVRs indicated 1000,650 and 1400 meters with winds from 90 degrees at 17m/s gusting 22m/s (33 knots gusting 43 knots). The crew aborted the approach to runway 06 and entered a hold. About 10 minutes later ATC reported the RVR for runway 02 was 1300, 600 and 2800 meters, winds were from 350 degrees at 4m/s gusting 15 m/s (8 knots gusting 29 knots), ILS approach was available. The crew decided to remain in the hold, the reported conditions still being below their minima. Another 3 minutes later ATC reported the conditions for runway 06 being RVR 3500, 1500 and 3500 meters, winds from 090 degrees at 7m/s gusting 19m/s (14 knots gusting 37 knots). The crew accepted the approach to runway 06. The crew lowered the gear, set the flaps to 15 degrees and was handed off to tower, tower cleared the flight to land on runway 06 reporting the winds from 090 degrees at 7m/s gusting 11m/s (14 knots gusting 21 knots).

Descending through 1100 feet the crew received an aural announcement "monitor radar display", the captain asked "what did he say?", the first officer replied a windshear warning was being predicted. Descending through 850 feet an aural warning occurred: "Go Around! Wind Shear ahead!". Although the crew was required to comply with the wind shear warning and to go around, the crew continued landing. Descending through 160 feet AGL, about 850 meters ahead of the runway threshold, the crew received the warning "Windshear! Windshear! Windshear!" Although the crew was requiring to immediately go around on receiving this warning, they continued the landing. Descending through 110 feet the first officer asked the captain "do you see the runway" at which point the captain initiated a go around. The crew subsequently stated a heavy rain fall was moving in dramatically reducing visibility. The aircraft began to climb after reaching 50 feet AGL about 150 meters before the runway threshold.

The aircraft climbed to 3100 feet and entered a hold. ATC told the crew RVR for runway 06 was now 2500,2600 and 2400 meters. The crew decided to attempt another approach. After being handed off to tower again tower reported RVR at 6000, 3500 and 3100 meters, winds were from 200 degrees at 4 m/s gusting 8 m/s (8 knots gusting 16 knots). The crew lowered the gear again and set the flaps to 15 degrees. Tower informed again, that the preceding aircraft had chosen to go around.

After intercepting the localizer, about 5nm before the runway threshold, the crew set the flaps to 30 degrees and intercepted the glide slope. Descending through 1100 feet the crew again received "Monitor radar display!", descending through 1050 feet the crew received "Go Around! Windshear ahead!" Again, the crew continued the descent and did not go around.

Data off the flight data recorder suggest significant gusts of wind, autothrust responded changing engine N1 between 30 and 90% N1.

Descending through 460 feet AGL the EGPWS sounded "Windshear! Windshear! Windshear!", the crew again continued the descent.

"Descending through 75 feet AGL the crew disconnected the autopilot and autothrust, IAS at that point was 169 knots and speed over ground 178 knots. At the time of touchdown the wind came from 170 degrees at 4 m/s (8 knots), the RVR was 6000, 5000 and 6000 meters, there was light rain, thunderstorms over the aerodrome, runway braking coefficients at 0.5, 0.5 and 0.5, the runway was covered with a layer of water of 3mm, coverage about 26-50% of the runway surface. Following the disconnection of autopilot and autothrust the airspeed further increased, the sink rate reduced. The aircraft touched down 1300 meters past the runway threshold at 160 KIAS (170 knots over ground).

Following touchdown spoilers deployed and auto brakes engaged. Reverse Thrust however was only applied 20.5 seconds after touchdown. 2160 meters before the runway end the deceleration reduced, the captain applied manual brakes 13 seconds after the autobrakes engaged. 26 seconds after the autobrakes engaged the aircraft went past the end of the runway, broke through the perimeter fence and went into the river bed, a fire occurred in the left engine."


Offline joeyb747

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