New Delhi, March 7 :     An Indian Air Force transport plane veered out of control minutes before touchdown at Delhi airport this morning, slamming into a cluster of bricklayers? huts and killing 22 people as it exploded into a ball of fire. The Russian-built An-32 aircraft swerved off its landing path after hitting high-voltage electric cables, clipped a brick boundary wall and vaulted into a massive water reservoir in Pappankalan area of south-west Delhi, barely 2 km from the runway. Dozens of huts of workers building the water tanks were flattened. The plane, flying on the Agra-Delhi-Gwalior sector, rammed into the cables after misjudging the height due to poor visibility, officials said. The dead included 15 IAF officials on way to a training camp in Allahabad and four crew members from IAF?s para-training school in Agra. A woman labourer and her two children were also killed, police said. This is probably the first time that so many defence personnel have been killed in a single crash. Among the victims were 10 officers, four of them wing commanders. Today?s crash is the second in two days after an Air France cargo plane went up in flames in Chennai airport on Saturday. It came on a day when the IAF was displaying its firepower at ?Vayushakti-99? in Pokhran before defence minister George Fernandes. Twelve persons were injured in the crash, which left the front half of the plane embedded in the water tank and its truncated tail end lying in a heap of blackened, twisted metal on the ground. The aircraft, which took off from Agra for Allahabad via Gwalior and Delhi, was given clearance to land by the air traffic control at 8:20 am. But it suddenly disappeared from radar screens and crashed within five minutes, ATC sources said. The black box and cockpit voice recorder are untraced, but a clock recovered from the site was stuck at 8:23 am, a senior police officer said. The IAF, the Directorate General of Civil Aviation and the Airports Authority of India have launched simultaneous inquiries into the accident. The airport remained closed for three hours when firefighting and rescue operations were underway. A retired air marshall said the airport was suddenly enveloped in thick fog that reduced visibility to near zero and the plane undershot the runway. Airport authorities had declared the area unsafe for residences, but it was not evacuated, he said. An ATC guild release said visibility was reduced to 500 metres at the time of the crash. This could be why the pilot descended lower than the required height. The guild said the officer on duty unsuccessfully tried to establish contact through all available frequencies after the plane vanished from the radar screen. Then he sent a jeep towards the runway to check if the plane had landed as aircraft were frequently ?found missing on the radar due to transponder incompatibility?. In Pokhran, Fernandes said the crash could not be related to the issue of modernisation of the air force. Delhi chief minister Sheila Dixit visited the crash site.