‘Poor visibility, not technical fault, likely crash cause’

‘Poor visibility, not technical fault, likely crash cause’

U Tejonmayam & V Ayappan TNN

Chennai:  09.12.2021

Foggy conditions and poor visibility could be factors that caused the Mi-17 V5 carrying CDS Gen Bipin Rawat, his wife and several others to crash in Coonoor, aviation experts said, though official word on the reason for Wednesday’s fatal accident is awaited.

They said chances of technical faults are remote because it was a planned flight with VIP passengers. “The chopper is capable of flying in bad weather, but the terrain was hilly and it appears to have fallen from a low altitude,” an expert said.

Visibility may have dropped considerably because of foggy conditions or low clouds over Coonoor around 11.30am on Wednesday. According to the IMD, Coonoor reported 4mm rainfall till 8.30am on Wednesday and the maximum temperature during the day was 19o C.

“We had forecast light to moderate rainfall in hill stations. Only for the plains we had forecast mist or fog. It is difficult to forecast fog for valleys and hilly terrain because both satellite and radar cannot capture that. Fog conditions can be reported only by seeing it. Even then it is difficult to differentiate between fog and low clouds,” said N Puviarasan, director, Area Cyclone Warning Centre, IMD Chennai.

Experts said fog appears as a cloud near ground level, reducing visibility. Fog usually forms at a relative humidity of about 100% that may occur when there is increased moisture in the air or when the temperature is decreasing.

IMD officials said they were not asked for local weather conditions during VIP movement to Wellington and the IAF has its own facility to track it. “They don’t share weather conditions or forecasts from their area either,” an official said.

Skymet Weather chief meteorologist Mahesh Palawat said Coonoor had shallow fog and cloudy weather on Wednesday morning (8.30am) and dense fog with nearly no visibility at 5.30pm. “There could be shallow fog or low clouds during the day,” he said.

No May Day call before crash, says Coimbatore ATC

In contact with destination control.” That was the last message from the pilot of the Mi-17V5 to Coimbatore ATC before the aircraft changed over to the defence ATC around five minutes from landing at the Wellington base on Wednesday. The changeover happened at around 4,000 ft, before it crashed, reports V Ayappan.

Coimbatore ATC sources said there was no May Day call, which is usually transmitted on open VHF frequency for all to hear. Only rarely do they transmit such calls for help on an exclusive emergency frequency, said an official. “The helicopter was supposed to return within 10 minutes of dropping off the passengers,” the official said. The chopper’s movement was not tracked on radar because Coimbatore does not have one that can map low-altitude flights.