Runway excursion Accident Antonov An-12B 4K-AZ25,

ASN Wikibase Occurrence # 320076

Date:	Wednesday 18 May 2016
Time:	14:07
Type:	Antonov An-12B
Owner/operator:	Silk Way Airlines
Registration:	4K-AZ25
MSN:	3341209
Year of manufacture:	1963
Total airframe hrs:	19828 hours
Cycles:	9107 flights
Engine model:	Ivchenko AI-20M-6
Fatalities:	Fatalities: 7 / Occupants: 9
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	Dwyer Airport (DWR) - Afghanistan
Phase:	Take off
Nature:	Ferry/positioning
Departure airport:	Dwyer Airport (DWR/OADY)
Destination airport:	Mary Airport (MYP/UTAM)
Investigating agency:	MAK
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
An Antonov An-12B cargo plane, operated by Silk Way Airlines, overran the runway during takeoff from Dwyer Airport, Afghanistan, and burst into flames. Seven of the nine occupants suffered fatal injuries.

The crew planned to fly from Baku (Azerbaijan) to Bagram (Afghanistan), Dwyer (Afghanistan), Mary (Turkmenistan) and then back to Baku. The flight legs to Dwyer Airport were uneventful.
At 13:11 the crew started the engines on the apron at Dwyer Airport. Engine no.2 was the last to be started up at 13:47 hours.
Before the takeoff the captain distributed the duties within the crew, nominating the first officer as the Pilot Flying, and himself as Pilot Monitoring.
After the engine startup the crew initiated taxiing to perform takeoff on runway 23. The concrete runway at Dwyer measured 2439 m by 37 m.
In the course of the takeoff preparations, at 13:57:56 the flight mechanic reported an increase in MGT of engine no.3 above the acceptable level: "Engine 3, look, engine temperature over six hundred, over seven hundred", which was confirmed by the first officer: "Yes, its getting temperature" while the captain asked to be more attentive.
The takeoff was performed with Flaps 15. As the checklist was being read, the captain ordered to lock the propellers. After the captain's order to lock the propellers a slight increase in torque values was recorded on engine no.1 and 4, and in 17 seconds also engine no.2. There was no evidence that the propeller of engine no.3 was locked.
At 13:59:42 the crew initiated the takeoff. Before the takeoff the ATC advised the crew on the wind direction and speed on the runway: 280° 14 knots (7 m/sec) gusting 26 knots (13 m/sec). Thus it was quartering headwind and the headwind component might have been 5 to 9 m/sec.
While performing takeoff the crew first increased thrust on engines no.1 and no.4 and then on engine no.2 after 10 seconds. The thrust of the three engines was about 50 kg/sq.cm as per torque indicator (lower than takeoff mode). The third engine was still operating in the ground idle mode, though the CVR did not record any crew callouts concerning engine no.3 operation parameters.
Based on the CCTV system of Dwyer Airport the takeoff roll was initiated almost from the runway threshold and was conducted to the left of the runway centerline. No significant deviations from the takeoff course during the takeoff roll were recorded. During the takeoff roll the rudder was deflected left close to extreme. Probably the pilots were also applying differential control on engine no.2 to decrease the right torque moment.
At 14:00:14 at approximately 120 km/h IAS the "Engine no.3 negative thrust" signal started. At that time the aircraft was about 430 m away from the start of the takeoff roll.
At 14:00:42 engines no.1 and no.4 thrust was increased up to 63 kg/sq.cm as per torque indicator (consistent with takeoff mode for the actual flight conditions). At that time the IAS was about 150 km/h. Engine no.2 thrust was increased up to the same value only 23 seconds later at about 200 km/h IAS. At that time the aircraft was about 840 m away from the runway end. Engine no.3 was still operating in ground idle mode. Approximately 260 m before the runway end at a speed of 220 km/h IAS (maximum speed reached) nose up input on the control column was started. The aircraft did not lift off. After rolling all along the runway the aircraft overran the runway onto the ground at a speed of 220 km/h.
While moving on the ground the aircraft sustained significant damage, which led to a post-crash fire that destroyed most of the aircraft structures. Out of the nine persons on board seven were killed and two were seriously injured and taken to hospital.

The accident with the An-12B 4K-AZ25 aircraft was caused by the decision of the crew to take off with a failed engine No. 3, the propeller of which was not feathered. During the entire takeoff run, engine No. 3 remained at ground idle, as a result of which the engine propeller created a negative thrust that increased as the speed increased, preventing the crew from reaching the take-off speed of the aircraft from the runway.

The crew did not take measures to stop the takeoff, which led to the aircraft overrunning the runway at a speed of 220 km/h, its destruction, followed by fire.

Accident investigation: