Uganda is attempting to determine why three of its helicopters crashed earlier this month.

Three helicopters, along with a Russian-built Mi-17, were to be deployed to support Ugandan troops assigned to the African Union Mission for Somalia, to which Uganda has contributed troops since 2007. AMISOM has been fighting al-Shabaab militants.

AU Commission for Somalia Special Representative Boubacar Diarra said the helicopters were being sent to Somalia to give AMISOM an air component for the first time.

He said the helicopter deployment "remains critical for operational as well as logistical support and medical evacuation."

The three Mi-24 and Mi-17 helicopters were all built by the Russian Federation's Moskovskii vertoletnyi zavod im. M.L. Miliia.

Apart from providing aerial cover for AMISOM ground operations, the helicopters were to act as aerial escort for convoys as well as assist in emergence rescue, evacuations, and air searches for the Burundian, Kenyan and Ugandan forces deployed with AMISOM.

After leaving Kenya's Soroti Flying School, the helicopters' pilots were ordered to fly in five fuelling loops mostly over Kenyan airspace from Soroti before arriving in Baidoa, a city in south-central Somalia, 159 miles northwest of Mogadishu, The Independent newspaper reported.

The route flew over Africa's second highest mountain range and Ugandan military officials were concerned that, once within Somalia airspace, the aircraft might come under fire from militias attacking them with surface-to-air missiles.

Roughly 12 hours after takeoff, one of the Mi-24 helicopters sent a distress call to Nairobi that it had crashed into Mount Kenya. Several hours later, two more Mi-24s were reported missing. Seven Ugandan soldiers, including two senior pilots, died in the three crashes while 15 were rescued.

The loss of three aircraft in one day prompted the Ugandan military to search for causes.

The Ugandan officials maintains the position that the helicopters were flying in an aerial military formation, a strategy to defend each other and were hampered by bad weather, which is known to change quickly in the area of Mount Kenya, whose volatile weather can include blizzards.

With that in mind, Ugandan officials are investigating all possible causes, including pilot error, equipment malfunction and weather.

The Moskovskii vertoletnyi zavod im. M.L. Miliia has been building Mi-24s since 1972, then for the Soviet air force. Since the collapse of the U.S.S.R. in 1991, Mi-24s have since been exported to 30 countries. Soviet air force pilots called the Mi-24 the "letaiushchii tank" or "flying tank," and the Mi-24s, NATO codenamed "Hind," saw extensive service with the Soviet military in Afghanistan. The Russian media has strongly defended the Russian helicopters' ruggedness and reliability.

Ugandan defense officials said the helicopters were purchased in 2003, while the Stockholm International Peace Research Institute reported they cost roughly $10 million.