Brannslukkerhavariet i Irkutsk - Curt Lewis

Several terrain warnings sounded before Il-76 crash

Russian investigators have determined that terrain collision-avoidance warnings repeatedly sounded in the 7min before an Ilyushin Il-76TD struck a hillside while combating wildfires.

None of the eight crew and two other personnel on board the emergency ministry transport survived the 1 July accident in the Kachugsky district of Irkutsk.

The Interstate Aviation Committee says the firefighting aircraft (RA-76840), which had been stationed at the Belaya airfield, departed at 10:19 local time.

It was directed to a primary fire zone and the captain ordered the altimeter set for 1007mb. The aircraft descended to an altitude of 1,100m (3,600ft), on a heading of 045°, decelerating to 186kt.

The aircraft exited the primary zone at a radio altimeter height of 250-400m and, at around 11:04, it turned left onto a heading of 342° to reach a secondary fire zone.

Investigators state that the aircraft was subsequently flown manually. The captain instructed a further descent and the Il-76 conducted right turns to take its heading to 190°, descending to 1,000m altitude - some 210m above ground.

Cockpit-voice recorder information shows that, over the last 7min of flight, audio 'terrain ahead' and 'pull up' warnings sounded "repeatedly", says the inquiry, as the aircraft crossed the undulating landscape.

As it rolled out onto the southern heading the Il-76 was heading towards a hill with a summit of 945m. But the captain continued the aircraft's descent until it collided with the hill just after 11:13, some 55min into its flight.

The Il-76 struck trees and carved through the forest, hitting the ground 415m further on, coming to rest at a height of 886m on the hillside, some 40m above the point of tree contact.

According to the crew of a Beriev Be-200 deployed to search for the Il-76, weather conditions in the area were characterised by heavy smoke.

The 22-year old Il-76 had been one of three modified with firefighting capabilities, and it had also been fitted with sophisticated avionics including satellite-based navigation and enhanced ground-proximity warning systems.

Its captain was highly experienced with over 8,700h on the type, from a total of more than 11,200h.

Investigators have issued a preliminary recommendation that crews familiarise themselves with features of the ground-proximity warning systems and the actions necessary when alerts are triggered.