The US Federal Aviation Administration will cease funding for 149 contract air traffic control towers in three phases beginning 7 April, as a result of cuts to the agency's budget.
The agency, which identified on 22 March the 149 towers that will be impacted, says today that funding for 24 of these towers will stop on 7 April.
Funding for another 46 towers will cease on 21 April, and for the remaining 79 towers, on 5 May.
Most of the towers affected are at general aviation airports although some airports, such as Branson and Ithaca, are served by commercial carriers.
Airport operators whose towers are affected may choose to operate as a non-towered airport or continue to provide tower services as a non-Federal control tower, says the agency today.
"The FAA is prepared to discuss the continued use of buildings and equipment with airports for those who desire to continue providing tower services. The FAA will also discuss the availability of reimbursable agreements where the airport can reimburse the FAA to provide other services," it adds.
The agency says that although funding for the towers will cease from 7 April, it will likely take up to 90 days before it begins disconnecting and removing equipment from the affected towers.
"FAA-owned and maintained equipment that remains with the tower after becoming a non-federal tower will continue to be owned and maintained by the FAA subject to future discussions and possible agreement with the airport," it says.
The agency says it will work with airports to ensure a common traffic frequency, as well as other communication capabilities, is available to pilots to operate at non-towered airports.
US airline trade association Airlines for America has said its members have no plans to cancel or suspend flights as a result of the tower closure, and that they will work with the FAA to minimise the impact to passengers.
The tower closures are a result of $637 million in cuts to the FAA budget through its current fiscal year ending 30 September, as part of $85 billion in cuts across the US federal government budget.