Incidents of passengers being denied boarding by Indian airlines have doubled in the past one year, according to the government's air traffic data.

However, the procedure laid down by the country's aviation watchdog ensures that people are unlikely to be thrown out like David Dao, a passenger on a United Airlines flight, who was dragged from his seat because of overbooking.

A total of 18,242 passengers were not allowed to board aircraft between April 2016 and February 2017. This is up from 10,561 passengers not allowed on board aircraft during the same time period in the preceding year.

As per the data for 2016-2017, more than 80 per cent of the passengers affected were those who flew Jet Airways and 14 per cent were Air India fliers, according to the air traffic data.

“A passenger could be denied boarding primarily for three reasons. If he/she turned up late at either the check-in counter or the boarding gate, for security reasons and due to overbooking of a flight,” former Director General of Civil Aviation Kanu Gohain said.

While most airlines officially maintain that they don't overbook their flights, industry insiders admit that selling “5-10 per cent” seats over and above the actual seating capacity of an aircraft is a norm across the world as they don't want planes to take off with empty seats in case of no-shows.

“Optimal inventory allocation is broadly governed by two factors ~ accurately forecasting passenger demand and maximising revenue by accounting for cancellations and no- shows,” explained an Air India official who oversees revenue management at the airline. The Directorate General of Civil Aviation (DGCA), too, approves the practice.

“To reduce the possibility of a flight departing with empty seats, airlines generally overbook flights to a limited extent. In case of overbooking, an airline may deny boarding to you even if you hold a confirmed booking for travel on the flight and reported for the flight well within the specified time,” according to information on DGCA's website.

The DGCA, in its Civil Aviation Requirements (CAR), lays down a two-step procedure that airlines must follow in such circumstances.

“An airline must first ask for volunteers to give up their seats so as to make seats available for other booked passengers to travel on the flight, in exchange for such benefits/facilities as the airline, at its own discretion, may wish to offer,” according to DGCA.

However, if no one comes forward, an airline can take a decision on who to deny boarding but is liable to provide a monetary compensation as per rules.

“If the boarding is denied to passengers against their will, the airline shall as soon as practicable compensate them in accordance with the provisions,” the DGCA rule adds.

As per norms effective from 1 August 2016, the compensation for not allowing a passenger to board the flight was raised from Rs.4,000 to Rs.20,000. The compensation amount is higher if the alternate flight is scheduled for departure after a gap of 24 hours.