The peak-hour vacant slots, which have been allotted but are not being used by airlines, would be auctioned "on an experimental basis", according to a proposal of the Civil Aviation Ministry.
The airlines wanting prime-time departure and arrival slots would have to bid for their preferred choices if the experimentation was successful, the sources said.
As per the current practice, an airline has to file its flight schedule with the Directorate General of Civil Aviation which allocates them in consultation with airport operators in line with the World Slot Guidelines of the global airlines' body International Air Travel Association (IATA).
An airport slot is defined by IATA as a permission given by a coordinator for a planned flight operation to use the full range of airport infrastructure necessary to arrive or depart at an airport on a specific date and time.
The auction move has been adopted following complaints of partiality by some airlines, especially at busy airports like the ones in Delhi, Mumbai, Kolkata and Chennai, with all carriers clamouring for prime-time slots at these airports.
A new computerised system of slot allotment would be introduced at airports to take over the job that is currently handled by DGCA and airport operators, the sources said.
To begin with, prime time slots, which have been allocated to an airline but are not being used by it due to capacity constraint or other reasons, would be the first to be auctioned, the sources said.
These slots would be identified at those airports where the capacity is constrained due to lack of sufficient infrastructure, they said, adding that some airlines might lose their unused prime slots if auction is implemented.
Recently, DGCA had found that certain airlines were neither utilising their alloted slots, nor were they ready to surrender them, prompting the regulator to take steps to re- allocate unused slots.
The official sources, however, clarified that the auction route was not aimed at generating additional income for the government or airport operators but to ensure efficient use of airport infrastructure in a transparent and equitable manner.
Industry sources said that the auction system was introduced in the United States but later rescinded after the courts ruled against the move following complaints by airlines. Since then, the US and the European Union have been studying slot allocation to make modifications in them.
In 2008 under the Bush Administration, US regulator Federal Aviation Administration initiated a proposal to auction 10 per cent of the slots at New York's three major airports (JFK, LaGuardia and Newark).
These proposals were met with criticism from airlines and IATA as well as legal challenges from the US Air Transport Association and the Port Authority of New York and New Jersey (the airports operator).
In May 2009, the Obama Administration rescinded the plans for slot auctions after the US Court of Appeals stayed the proposal.
The industry sources also asked as to where the money raised from slot auctions would go and suggested that the best solution would be to put in place more and advanced infrastructure to meet the industry needs and free up airspace wherever appropriate.
They said airlines the world over do not generally favour a slot management system. "In an ideal world, airlines would be able to fly where they wanted, when they wanted. But this is not the ideal world," they said quoting IATA studies.
In many cases, securing prime slots was only half the battle. Gate access and terminal facilities have to be negotiated separately with the airport owner, which leads to "added complexity and, therefore, "higher costs," the sources said.