The claims of chief minister Mamata Banerjee that her life was endangered as another aircraft allegedly appeared in her flight’s pathway and the alert pilot averted a possible collision doesn’t hold water as a veteran pilot-cum-trainer said that it is an impossible scenario in today’s age when an aircraft can come that close to another due to a Traffic Collision Avoidance System (TCAS), which enables pilots to take action much before a collision.

Following chief minister Mamata Banerjee’s allegations that she was saved by an alert pilot as he steered away the plane right on time when another plane suddenly appeared in front of her aircraft, Trinamool Congress (TMC) MP Sougata Roy today visited the Kolkata airport, amidst a protest outside the airport premises by party workers, seeking details from the Airports Authority of India (AAI) regarding what actually took place that allegedly jeopardized the chief minister’s life.

A senior pilot of an Indian airline, who has also been a trainer for years, told The Statesman that the scenario being narrated by the chief minister is “absurd” in today’s time and age.

Commenting on Miss Banerjee’s allegations that another aircraft suddenly appeared in front of her plane, a Dassault Falcon 2000, the pilot, requesting anonymity, said, “It is literally impossible. Every aircraft in today’s time has a traffic collision avoidance system (TCAS). This system gets triggered when another aircraft is nearby. A pilot gets more than adequate time to change the path of his/her aircraft.”

The pilot remarked that traffic in the air does not work in the same way as road traffic where a car may, without warning, appear in front of another vehicle from an alley connected with the main road. He said that a pilot from one aircraft can spot the other plane when it is within 40 nautical miles or 74 km, giving it enough time to change position.

He explained that the TCAS warning is time-dependent, i.e time from a possible collision, and the distance will depend on the combined speed at which two aircrafts approach each other. He added that a TCAS warning, like in an A320 aircraft’s navigation display, resembling an ‘open white diamond symbol’, will pop up at around 40 NM (74km) or more depending on the type of TCAS and aircraft speed.

“Normally, around four minutes before the collision, the open diamond will turn into a fully white diamond, and at around 45 seconds before the collision, it will turn into an amber coloured circle when the system gives a traffic advisory warning. At 25 seconds before the collision, it turns into a red circle and provides a resolution advisory where it will tell the pilot whether to maintain level, climb or descend and at what rate. Both aircraft, equipped with TCAS, communicate with each other via data link, without any pilot control and decide the best course of action to avoid a collision. At this point, the pilots don’t even need to wait for air traffic control orders.”

The pilot feels, what happened to the CM could be merely a case of air turbulence or mechanical failure. “It is mandatory by DGCA that all Indian aircraft has a TCAS system installed.”