Juba Air Cargo AN12 near Malakal on June 27th 2008, triple engine failure enroute

Last Update: May 20, 2013 / 23:34:33 GMT/Zulu time

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Incident Facts

Date of incident
Jun 27, 2008

Classification
Crash

Aircraft Type
Antonov An-12

ICAO Type Designator
AN12

Sudan's Central Directorate of Air Accident Investigation (SAAICD) released their final report concluding the probable causes of the crash were:

- The three engines failure constitutes the main cause.

Contributory factors:

- En-route bad weather and pilot visual entry into an embedded thunder storm.

- Un-serviceability or sudden failure of weather Radar.

- Accumulation of ice led to the blockage of the engines air intake assembly (IGVA).

- The nature of the impact area was forest, this caused the detachment of the aircraft parts. The running engine (No.2) caused the fire.

The crew consisted of a captain (ATPL, 13,300 hours total, 5,000 hours on type), a first officer (ATPL, 11,535 hours total, 3,300 hours on type) and a flight engineer (F/E, 15,400 hours total, 5,191 hours on type).

The aircraft departed Khartoum's runway 18 and climbed to FL170. About 72 minutes after departure the aircraft encountered turbulence resulting in vertical speeds of up to 340 feet per minute. 5 minutes later engine #1 (outboard left) failed, another minute later engine #3 (inboard right) failed and another 40 seconds later engine #4 (outboard right) failed. The aircraft entered a descent of about 3450 feet per minute descending through 800 feet MSL about 3:40 minutes after the failure of engine #1. The crew subsequently arrested the rate of descent at 600 feet per minute, the crew attempted to restart engine #3 which succeeded just moments before the aircraft impacted a tree at a height of 8 meters shutting the engine down again, 58 meters past point of first impact the left hand stabilizer detached from the aircraft and the aircraft burst into flames, 64 meters past first point of impact the aircraft hit the ground, the aircraft disintegrated with the main portion coming to rest 264 meters past point of first impact at position N9.5313 E31.4453.

The crash site was located by rescue services by triangulation of the survivor's mobile phone, helicopters and fixed wing aircraft were dispatched to the scene. One survivor was recovered from the crash site upon arrival of rescue forces, 5 bodies were recovered from around the wreckage having been thrown out of the aircraft, two people remained missing.

The flight crew was identified, the occupants had succumbed to burns covering 90-100% of the bodies and multiple injuries/fragmentation.

The black boxes were recovered, both cockpit voice recorders did not contain recordings of the accident flight, the flight data recorder however contained the data of the accident flight from departure to impact with ground.

The SAAICD analysed: "On the day of accident, en-route weather conditions were very bad (Thunderstorms, rain, hail, icing and turbulence) (MET forecast attached). There was a huge thunderstorm to the right of track with small paths in between the CB clouds to the far left and right. Aircraft weather radar was not operating at that time, because according to the survivor report the pilot made a right turn which led him direct in the centre of an embedded CB. Embedded thunderstorms are obscured by other clouds and it is impossible for a pilot to visually detour around them, they present a particular hazard to IFR flights."

When the aircraft entered the thunderstorm it "encountered heavy turbulence, icing, hail and up and down draft which led to the failure of three engines No 1,3 and 4 except engine No. 2" and began a rapid descent at about 3450 fpm and accelerated to an indicated airspeed of 350-372 knots equivalent to 0.78 mach. The crew attempted several times to restart engine #3, when the engine finally started the aircraft already impacted a tree.

The aircraft was equipped with anti-ice systems, however, the captain "entered into the embedded CB without seeing it, so it is positive that the deicing was not on", the SAAICD argued the captain did not know there was an embedded thunderstorm, no increase in engine torque was visible on the flight data recorder as would be expected with the activation of the anti-ice systems.

The SAAICD stated: "Engine No.1 stopped, one minute later engine NO.3 stopped and in 40 seconds engine No.4 stopped due to ice accumulation in the air intake which closed the air flow and leading to failure of the above mentioned engines."
Incident Facts

Date of incident
Jun 27, 2008

Classification
Crash

Aircraft Type
Antonov An-12

ICAO Type Designator
AN12

This article is published under license from Avherald.com. © of text by Avherald.com.
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