Ronald Beck was getting out of his car in a parking lot at Washington National Airport Tuesday night when a gunman forced him back in and told him to drive to the District. Halfway across the 14th Street Bridge, the man fired one shot in the air to show that the gun was loaded.

Beck was released unharmed shortly afterward, but the man fled in his car.

It was the first of three such armed robberies in about three hours that night in the same parking lot at the airport. No one was injured.

Airport police believe that one man is responsible for all three robberies. Each time, the robber was described as a black man in his mid-30s, somewhat disheveled and reeking of alcohol.

It all began about 6:15 p.m., when Beck, a 44-year-old Fairfax County resident, was getting out of his car in a parking lot near the North Terminal and the Metro Station. The man forced Beck into the driver's seat and sat next to him on the passager side. He placed the gun to Beck's side and told him to drive.

As they were riding, the man told Beck he had two children in the hospital and took Beck's wallet, containing $150 and credit cards. At Fourth Street and Massachusetts Avenue NW, the man told Beck to get out of the car. Beck did and the man drove off.

Beck borrowed a quarter from a woman passerby and telephoned D.C. police. About 6:45 p.m., D.C. police picked Beck up and took him to headquarters, where he filed a report.

About an hour later, as Beck was still giving a report to police, his car was found by a D.C. police officer in a parking lot at 1415 H St. NW. A man was tampering with the car. He was later arrested, but Beck told police it was not the person who had robbed and abducted him.

At 9 p.m., Robert Moore arrived on the Eastern shuttle from New York. He headed for his car in the short-term parking lot B, about 10 to 15 feet from the pay booth.

"I had put my two brief cases on the seat and was getting in, when a little fellow came on like a wino, saying, 'Cuse me, 'Cuse me.' I said, "Excuse me' and tried to close the door when he pointed a nickel-plated revolver at me. My immediate reflex was to hand him my wallet. I said, 'Excuse me.'"

"As he started slipping in, I started slipping out," said Moore, who by now had grabbed his briefcases containing his company's annual reports. "I was willing for him to have my car, my money, but not my briefcases."

Moore, a 39-year-old vice president of an insurance brokerage firm, said, "I was in the process of excusing myself when he said, "If you move another step, I'm going to drop you where you are."

"I didn't think he would get a good shot at me," Moore said. "I said (to myself) this guy is so spacy and hostile, the best thing is to get out of his way."

So Moore ran. He ran to the North Terminal, where he told his story to an airline employe who called the airport police.

Meanwhile, John M. Forrister had picked up Sheila Alley and her 23-month-old daughter, Melinda, who had arrived on Flight 506 from Atlanta.

Shortly after 9 p.m., they were getting into Forister's 1972 dark green Opel, which was parked in the same area where Moore moments earlier had been accosted. As they were getting into the car, a man reeking of alcohol and pointing a gun told them "he had to get out of the parking lot."

"He appeared out of nowhere," the 28-year-old Alley said.

Alley, who was placing her daughter in the back seat when the gunman struck the gun in her back, said, "It took a minute for it to dawn on me what was happening." "He appeared out of nowhere." The purse," said Forrister, a GSA employe. ""Fortunately, neither of us had any cash . . . he forced me to take the keys out of my pocket and give them to him."

The man then forced the three away from the car. He drove through the pay booth gate without paying the attendant as Forrister and Alley reached the booth. The attendant called the police.

"I happened to be in the wrong place at the right time," Forrister said. "There is nothing to be said to have a gun stuck in your face. We were lucky nobody got hurt.

"I would like to have my car back," said the 43-year-old Forrister, who late yesterday still had no word of the whereabouts of his car. "If he is caught, he'll probably be out on the street in a couple of hours."

Police late yesterday said they had made no arrest.

Moore said that the 9 p.m. robberies could have been prevented if D.C. police had notified airport police of the earlier incident involving Beck.

An airport spokesman said airport police were called by D.C. police Tuesday night and told of Beck's robbery and abduction. However, the spokesman said he did not know what time the call was made.

A D.C. robbery squad investigator said that generally a victim in this particular case would have been advised to report the incident to local authorities -- meaning the airport police. However, the District police would investigate the kidnaping report, the investigator said.

Moore said Beck appeared at the airport police office about 10:30 p.m. to report the incident while Moore was still there.

An airport spokesman said airport police, D.C. police and the FBI are working on the case.

Meanwhile, Alley said she had received a telephone call yesterday from Alexandria police who told her that her wallet, containing her credit cards and identification, had been found.

According to an Alexandria police spokesman, the wallet was found Tuesday night in an alley in the 3800 block of Mount Vernon Avenue.