Transportation Secretary Ray LaHood
Transportation Secretary Ray LaHoodAFP file

The United States Federal Aviation Administration ordered the shutdown of air-traffic control towers at 149 small airports due to budget constraints after the implementation of the "sequester" spending cuts.

Another 40 towers that were facing closure will remain open, either because shutting them "would have a negative impact on the national interest," or because they enjoy separate budgeting support, the FAA said, according to the AFP news agency.

"We heard from communities across the country about the importance of their towers and these were very tough decisions," Transportation Secretary Ray LaHood said in a statement.

"Unfortunately we are faced with a series of difficult choices that we have to make to reach the required cuts under sequestration."

The FAA is being forced to excise $637 million from its current budget under the sequester, which required the government to slice $85 billion from spending over the seven months beginning March in an effort to rapidly bring down the federal deficit.

LaHood warned last month that, in addition to the tower closures, FAA staff, including flight control staff, would be subject to furloughs, or mandated unpaid leave, of up to four days a month beginning in April as a cost-saving measure.

The FAA and airlines have warned that the closures, which begin on April 7, could slow flight traffic around the country, especially during the busy summer season.

The airports affected are generally low-traffic local facilities, though some feed traffic into larger hubs, AFP reported.

The FAA said however that some communities could assume the cost of their own on-site air-traffic control services.