Looking weary but happy, civilian pilot Geoffrey Tyler and two American mercenaries were reunited with family and friends here today after being released from prison in Angola.

Tyler, 33, a former Prince George's County resident and a graduate of DuVal High School, spent 21 months in an Angolan prison. The two mercenaries, Gustavo Grillo, 33, and Gary Acker, 28, were each imprisoned there for nearly seven years.

The three Americans, who arrived at JFK International Airport aboard an overnight commercial flight from Paris, were set free in Zambia Tuesday.

Their release came after years-long negotiations and a complicated prisoner swap that involved six nations, the Red Cross and a guerrilla organization.

"We're glad to be home," said Tyler, whose mother and brother still live in Seabrook, Md. "I missed my freedom."

Before his capture, Tyler had been living in Lakeland, Fla., and working as a civilian pilot for Globe Aero Ltd. Inc., a firm that ferries small aircraft to purchasers abroad. He was taken prisoner on Feb. 4, 1981, after his plane, which he was delivering to a buyer in South Africa, developed electrical problems, forcing him to land on a road in Angola.

Grillo, of Toms River, N.J., and Acker, of Sacramento, Calif., were both publicly tried and convicted of being mercenaries in 1976. Angola's Marxist government sentenced them to 30 and 16 years in prison respectively.

After a private, tearful reunion with relatives, Tyler told reporters he had lost 25 pounds during his incarceration. He said he had not slept since leaving Angola and was hoping to get some rest after returning tonight to his mother's apartment in Seabrook.

He said he was neither tortured or physically mistreated while in prison but was kept in isolation initially and denied even written contact with his family for months.

"I don't feel my treatment was inhumane as much as completely unjust," Tyler said, noting that he had been denied legal counsel and imprisoned even though he had never engaged in any mercenary activities against the Angolan government.

Tyler said he expects to resume flying for Globe Aero, and hopes eventually to go back to graduate school for a doctorate in history.

The former Army medical officer said the hardest moments during his imprisonment were when he learned that a beloved relative and some fellow pilots had died while he was incarcerated.

"I lost several friends and my grandmother," he said softly. "Obviously, you don't get a chance to say goodbye."

But that sorrow was behind him today as he stood with his arms around his mother, Marjorie, and his younger brother, Doug.

"I'm extremely happy and relieved," said Mrs. Tyler, a widow, while hugging her son close. "Nice Thanksgiving."