It was a blue-sky morning for flying.

Ken Rehmann and his co-pilot, Tom Kenny, had filed the required flight plan with the Federal Aviation Administration and were ready to start up their single-engine Piper Comanche for the trip to Essex, east of Baltimore. But before they could take off from College Park Airport, they needed to call federal air traffic control officials to get a special transponder code so that their flight could be monitored.

The move was mandated after the Sept. 11, 2001, terrorist attacks. Now, pilots flying any type of plane out of College Park must stay in close radio contact with the FAA and follow its rules in the so-called no-fly zone, or D.C. Flight Restricted Zone.

"Once we take off, we are in the [Flight Restricted Zone]," Kenny said recently.

The restrictions are many and they are tough. Still, Rehmann, of Bowie, and Kenny, of Upper Marlboro, say they are glad to be able to fly.

But the NASA employees may be in the minority when it comes to their enthusiasm for flying their small aircraft out of the Washington area.

Lee Schiek, manager of the College Park Airport, said that most of the pilots who once used the small airfield near the University of Maryland have moved their planes elsewhere because of the regulations.

The tighter restrictions apply to the so-called "D.C. 3" in the high-security zone: Potomac Airfield in Fort Washington, Washington Executive/Hyde Field airport in Clinton, and College Park.

The loss of those pilots has been difficult for College Park, which calls itself the world's oldest continuously operated airport. The airport, which also has a popular museum, was established in 1909 after Wilbur Wright went there to train military officers to fly the government's first airplane.

"Since 9/11, our air traffic has declined by 92 percent," Schiek said. "We are looking forward to the day when the federal government will consider more reasonable restrictions."

Such easing has begun elsewhere.

Recently, federal officials announced that private planes will again be able to fly in and out of Reagan National Airport on a limited basis. Under the new guidelines, 48 private flights will be allowed to use the airport each day, provided that passengers and crews are pre-screened and the flights are equipped with armed security guards, among other requirements.

Schiek said that to land at College Park, pilots must travel to the District, get fingerprinted and view a security tape, and go to Baltimore-Washington International Airport or Dulles International Airport for a background check.

Lt. Charles Davis of the College Park Composite Squadron of the Civil Air Patrol said his unit moved its plane to Tipton Airport in Anne Arundel County so members could train and conduct air patrol missions. Braxton Diggs, 16, a Civil Air Patrol cadet from Silver Spring, said he doesn't like the strict flying rules but understands why they are in place.

"It kind of stinks that you are restricted from training, but because we are so close to the nation's capital, there could be terrorist attacks," Diggs said.

Schiek recalled busier times at College Park Airport. Before Sept. 11, he said, pilots would fly in on Memorial Day and take Metro into the District to enjoy the festivities.

"We were once the primary single-engine airport for the Washington area," Schiek said, adding that during football season at the university, the airport had its own fly-in versions of the tailgate party. "We had all sorts of activities out here."

Still, some say they will use the airport no matter what the restrictions.

David Wills, for example, flies his Cessna 150 into College Park Airport from Hagerstown five days a week.

"It's pretty restrictive flying in and out of here," Wills said. "I didn't used to have to talk to anybody. Now I'm in constant communication [with air traffic controllers]. To me, it's getting to be routine."