An airplane goes by the control tower at the Frederick Municipal Airport as it lands on March 30, 2012. Automatic budget cuts have the tower and four others at small to mid-size airports in Maryland at risk for closure. (Sam Yu/Associated Press photo/The Frederick News-Post)

The Federal Aviation Administration said Friday that it would shutter 149 airport control towers early next month, including six in Maryland and Virginia.

The announcement, which affects mostly small airports, follows the mandatory federal spending cuts that went into effect earlier this month.

The closures include the towers at Lynchburg Regional in Virginia and at Martin State outside of Baltimore, and at the airports in Easton, Frederick, Hagerstown and Salisbury, all in Maryland. Until last year, Frederick, like many small airports, did not have a tower.

The Manassas Regional Airport tower, which was on the original list of those slated for closure, will remain open for now.

Even without a staffed tower, the airports are able to operate with pilots communicating their positions by radio or by using other FAA facilities for guidance. FAA Administrator Michael Huerta emphasized that his agency would work closely to ensure safe landing and takeoffs at the affected airports.

The agency had planned to make the announcement last week but held off because of the volume of appeals. The closures, which begin April 7, are part of the more than $600 million in cuts the agency must make.

“Unfortunately, we are faced with a series of difficult choices that we have to make to reach the required cuts under sequestration,” Transportation Secretary Ray LaHood said.

The towers slated to be closed are operated by FAA contractors. The FAA has not made a decision on towers staffed by FAA controllers at smaller airports, such as Manassas Regional, because such changes must be negotiated with the controllers’ union.

The FAA’s decision drew immediate criticism from many quarters, including union officials, private pilots and Republican leaders who had questions about how the closures would affect flight safety.

“The FAA made a bad situation worse by not utilizing a well-thought-out process for evaluating the value of air traffic control towers before ordering their closure,’’ said Paul Rinaldi, president of the National Air Traffic Controllers Association.

In a letter to LaHood, Sen. John Thune (R-S.D.) and Rep. Bill Shuster (R-Pa.), leaders on transportation issues, demanded more details on the closures as well as assurances that the shutdowns won’t compromise safety.

Once the automatic spending cuts went into effect on March 1, communities were given time to appeal the decision. Many lobbied aggressively, and Sens. Jerry Moran (R-Kan.) and James M. Inhofe (R-Okla.) proposed an amendment to the continuing resolution, which will fund the government for the next six months, to restore $50 million to keep the towers open. But the measure failed.

In a letter to Huerta, Rep. John Delaney (D), whose Maryland district is home to the Frederick and Hagerstown airports, emphasized the economic effect that the airports have on the local economy.

“Together these airports represent $200 million of business revenue and 2,500 jobs,” he wrote.

Craig Fuller, president of the Aircraft Owners and Pilots Association, faulted the decision to close the 149 towers, which make up about one-third of the nation’s control towers.

“This is no time for politics,” he said. “These towers were put into operation to ensure aviation safety. ”