Airlines might be asked to shell out additional charges for use of slots during peak hours at aerodromes, with the proposal being considered by the Airports Authority of India (AAI), according to a senior official. The proposal, once implemented, could also push the airfares higher as carriers might pass on the additional charges to the passengers. With rising air traffic and domestic airlines expanding their fleet, slots are a major issue, especially at busy airports such as in the national capital and Mumbai. Now, the AAI is looking at a proposal for levying extra charges from airlines for usage of slots during peak hours. AAI Chairman Guruprasad Mohapatra the proposal was at its level and was not a government decision yet. He also noted that feasibility as well as modalities of having additional charges slots during peak hours are being looked at. "It is being considered and global precedents are being collected. There are variable slot charges (at airports) in different parts of the world. It is not something new but in India we don't have (such) a policy," he told PTI. Currently, airlines are required to pay only fixed airport charges and no separate slot charges are levied. "It is being considered whether it is feasible, whether it can be done. If it has to be done, what are the modalities of doing it," Mohapatra said. Generally, peak hours are those time periods when the air traffic at an airport is high. The Airports Economic Regulatory Authority (AERA) regulates tariff and other charges for the aeronautical services rendered at airports. The AAI manages more than 120 airports, including international aerodromes and civil enclaves at defence airfields. India is one of the fastest growing aviation markets in the world. Earlier this month, global airlines' body IATA said India registered double-digit domestic air passenger growth for the 45th straight month in May.