A driver for the operator of Dulles Airport's Washington Flyer taxicabs was snared yesterday in a sting operation by the D.C. Taxicab Commission, which impounded the cab and said it would continue its operation until cabs stop making illegal trips into the city.

Farouq Massoud, the exclusive operator of Washington Flyer's 472-cab fleet at Dulles, also owns the Arlington Blue Top cab company. Because District rules prohibit Washington Flyer cabs from picking up customers in the city, customers who call the Flyer service from Washington are sent a cab from Blue Top.

Under a reciprocity agreement, Arlington cabs are allowed to pick up passengers in the District, but may take them only to Arlington. Massoud acknowledged in recent interviews that his Blue Top cabs are dispatched on trips from Washington to Dulles. D.C. cab officials have told him it is illegal.

"All they're concerned with is siphoning off the cream of the crop, the long trips," D.C. Taxicab Commission Chairman George Crawford said of Massoud's cab operation. "That's $45 that would've been generated for a D.C. cab operator, plus tip."

So yesterday, Crawford sent one of his employees to the Hyatt Regency Downtown, and instructed him to call Washington Flyer for a ride to Dulles. The employee did so, and the dispatcher told him a cab would arrive at 1:20 p.m., Crawford said.

A Blue Top cab appeared promptly at 1:20. The employee met the driver, Abdul S. Doudzai, and confirmed the Dulles destination. Then, a D.C. hack inspector handed Doudzai a civil summons with a $500 fine, and impounded Blue Top cab number 87, Crawford said.

Massoud said he was unfamiliar with the details of yesterday's episode, and he declined to comment.

As the hack inspector drove the seized cab away, he heard a dispatcher warn Blue Top drivers over the radio that anyone picking up fares in Washington is "doing it at your own risk," Crawford said.

Crawford said he took the action after reading Massoud's comments in The Washington Post last week saying that he did instruct his drivers to come into the District. Because only Washington Flyer cabs can wait in line for fares at Dulles, the District has responded by banning Flyer cabs from the city.

Drivers for Washington Flyer have complained that Massoud's Blue Top unfairly benefits from the advertising brochures given to each Flyer passenger from Dulles, which instructs riders to call Flyer for their return trips to the airport. The drivers also said the referral of calls to Blue Top eliminates any incentive for Massoud to fight for the right of Washington Flyer drivers to return to the District.

Abdalla O. Nasir, head of the Washington Flyer Taxi Drivers Association, said he was encouraged by the cab commission's actions. "Maybe now the airports authority will realize how serious this matter is and start fighting for Washington Flyer cabbies to pick up in Washington," Nasir said.

Tara Hamilton, a spokeswoman for the Metropolitan Washington Airports Authority, said the authority expects all of its contractors to follow the law. "If it is the law that everyone in the District of Columbia who wants to take a cab to Dulles Airport must take a D.C. cab," Hamilton said, "then we expect our taxicab contractor at Dulles to comply."