This file photo shows a small remote-controlled drone as it hovers in the sky during a meet-up of the DC Area Drone User Group in Middletown, Md. (Robert Macpherson/AFP/Getty Images)

On many afternoons, the skies above Gude Drive Field in Montgomery County are dotted with a mix of model electric airplanes and gliders, small drones and remote-controlled helicopters. The home field of the Capital Area Soaring Association, 16 nautical miles north of Reagan National Airport, provides open spaces and a safe haven where hobbyists can fly their machines.

Last week, the leaders of the 130-member group were advised by their parent organization that their safe haven is now a no-fly zone.

The Federal Aviation Administration sent out a memo to dozens of model aircraft sites in the Washington area telling them that they needed to halt activity because some users were flying within the “special flight rules area.” In other words, too many drones had been crossing into airport territory.

“We are asking for your help in spreading the word to the National Capitol Region model aircraft community that such activity is subject to enforcement action, and could damage our efforts to secure the interagency concurrence that is critical to this effort,” read the email from Brian Throop, manager of the FAA’s special operations security group.

The memo was what area drone hobbyists had feared for months.

Airspace restrictions were put into place in the Washington area shortly after the terrorist attacks of Sept. 11, 2001. In the ensuing years, model aircraft were prohibited from flying within 15 miles of Reagan National Airport.

In September, the FAA announced that drones were subject to a 30-mile prohibition around National, a zone where communications between aircraft and air-traffic control is required. That 30-mile prohibition had the effect of making the D.C. metropolitan area — from Northern Virginia nearly to Baltimore — a no-drone zone.

Model aircraft hobbyists, long told that the rule was 15 miles, initially thought the expansion of the restricted area was a mistake. The Academy of Model Aeronautics (AMA), a nonprofit group that promotes model aeronautics as a sport and recreational activity and says it has pushed responsible flying for 80 years, did not ask its members to abide by the 30-mile prohibition — until the recent advisory, which was detailed in a report by Vice Motherboard, a culture website.

“A lot of people felt that was kind of an error, that they had kind of lumped us in with regular aircraft outside of the 15-mile radius,” said Dom Perez, coordinator of the Soaring Association. “The FAA came to the AMA and said, ‘No, it’s not an error, and you need to tell your clubs to shut down.’ ”

In addition to 14 area AMA-member clubs, the shutdown affects sites overseen by the 2,500-operator DC Area Drone User Group. Officials with the group did not respond to a request for comment.

In a statement, the FAA said aircraft operating within 30 miles of National must have transponders that broadcast a code unique to the aircraft. Pilots of such aircraft need to remain in two-way radio communication with air-traffic control, the FAA said. Aircraft that do not meet those requirements cannot operate that close to the airfield, the agency said.

“Unmanned aircraft, including model aircraft, are ‘aircraft’ and are subject to FAA rules,” the FAA said.

The AMA pushed back against the restrictions Thursday, saying model aircraft have been operating “without incident” in the newly restricted zone for years.

“AMA understands that these restrictions are part of the security measures put in place to protect the U.S. Capitol and the Academy supports the government’s efforts to protect our national interests,” Rich Hanson, government relations representative for the AMA, said in a statement. “However, model airplanes and model aircraft enthusiasts do not pose a threat to national security but rather assist in the counterterrorism effort by serving as a community of eyes and ears familiar with the operation of unmanned aircraft and watchful of aberrant behavior.”

In his email to the AMA, Throop said the FAA was willing to work with the model aircraft groups.

“The last thing anyone wants to hear from the federal government is ‘be patient,’ but you folks have been patient, and understanding, and we sincerely appreciate both as we work to try and get you back in the air,” he said.

That has many model aircraft enthusiasts hopeful that the new restrictions are temporary, and that an agreement can be reached with the FAA as soon as mid-January.

Perez, the coordinator of the Capital Area Soaring Association, said it’s not the model aircraft clubs that should be punished, since they encourage safe flying.

“It’s people outside the clubs who seem to be flying over the White House fence, flying outside airports, where they shouldn’t be,” he said. “I’m trying to hunt these people down and get them to cooperate and play by the rules.”