Kolkata: The air ambulance from Ranchi to Delhi that crashed around half an hour after takeoff, killing all 7 occupants, did not sound a distress call before it went off the radar. Minutes before the crash, the pilot sought a deviation due to weather and officials granted it. However, officials at the meteorological centre in Ranchi said that despite weather warnings being issued, the crew of the turbo-propeller Beechcraft aircraft did not contact it before takeoff.Sources at Kolkata airport said the plane disappeared from the radar at Atali point, where the controller at Kolkata was to hand over the plane to the controller at Varanasi.Located around 90 nautical miles north-west of Ranchi and 104 NM south-east of Varanasi, the controller at Kolkata who tracked the flight triggered the alarm after the blip disappeared from the radar and he failed to contact the captain or the co-pilot over the radio. “The captain asked for a weather deviation and officials granted it. The flight, which climbed after taking off from Ranchi, initially asked for an altitude of 16,000 ft. At 7.30 pm, the pilot contacted again and sought permission to climb to 14,000 ft and no further. Officials allowed this. That was the last conversation the controller had with the flight cockpit. Exactly 4 minutes later, the aircraft disappeared from the radar,” a source said.An aviation expert said a lightning strike may have affected the transponder and electrical systems of the Beechcraft King Air C90A plane. The low flight level of the aircraft may also have led to interference with its VHF system. The head of the Ranchi Met centre, PP Baburaj, said rainfall and thunderstorm warnings were issued at 11 am and again at 5.10 pm for all departing aircraft on Monday.“In the morning, a bulletin was sent out, forecasting rainfall and thunderstorms accompanied by lightning in north-west and central Jharkhand. All pilots should have received the warning. At 5.10 pm, we issued a Nowcast of light thunderstorms with rain in some districts in the north-west sector,” the weatherman said.Typically, planes avoid cumulonimbus clouds because they pose severe, life-threatening safety risks rather than just discomfort. These clouds contain violent turbulence, intense lightning, heavy icing, hail and extreme wind shear capable of damaging aircraft structure. For smaller aircraft like a Beechcraft, flying through bad weather can be deadly.
