Passengers flying from Newquay Airport will have to pay a £5 fee to help secure the airport's future.
Passenger numbers have almost tripled in three years
Owner Cornwall County Council fears a big rise in costs when the MoD pulls out of adjoining St Mawgan in 2007.
The £5 fee, due to start on 29 October, will be added to the price of all passenger tickets, but children under the age of 16 will be exempt.
Questions have also been raised about increasing landing fees at the airport, which loses about £1m a year.
County councillor Andrew Mitchell, said: "The decision to introduce an airport development fee has been tough, but Cornwall County Council feels that this is essential in ensuring the future viability of the airport."
The council is spending £2.8m to improve facilities at the airport, including a new passenger terminal.
Passenger numbers have grown from 118,000 in 2002 to a predicted 334,000 for 2005.