They were both adventurers, passionate for flying. They had spent much of their lives roaming the world aloft: in fighter planes and transports and commercial airliners, in helicopters and even trainers and seaplanes. One had been shot down in battle and had been a jungle fighter in Southeast Asia; the other had become a senior pilot for Trans World Airlines.

But in recent years, John Stuart-Jervis, 68, a British-born naturalized American, and Alan Fraenckel, 55, who grew up near Schenectady, N.Y., found a new road through the skies -- in the whimsical wanderlust of sport balloons, soaring wherever the wind took them, over mountains and seas, across deserts and international borders, from Asia and Australia to Europe and North America.

They met at a cocktail party six years ago in St. Croix, in the United States Virgin Islands, where both had homes, and, friends said, quickly saw the flier in each other: the casual talk of parachute jumps, ditching at sea, the long hours at the controls with hundreds back in the cabin. And, having a mutual interest in ballooning, they soon became friends and sometimes a gondola team.

"They ballooned together many times," said Mr. Fraenckel's cousin, Rebecca Dale. "Alan went up every chance he got. When he wasn't in the air, he was on the phone talking about it. The word is passion."

Last week, the ballooning world's most prestigious distance competition took them from the Swiss Alps, across the skies of Europe, into Belarus, the former Soviet republic east of Poland. As they drifted there at 7,200 feet on Tuesday, tragedy struck -- a Belarussian helicopter gunship fired a missile that exploded their 75-foot hydrogen-filled balloon and killed the two men.

The Belarussian Government said nothing for 24 hours, then argued that the victims and two other teams in the Gordon Bennett Balloon Race that had been forced down by military aircraft had illegally approached a Belarussian air base and missile-launching site and had ignored warnings by radio and gunfire.

After rebukes from the White House and the State Department and a chorus of outrage from balloon enthusiasts who said that the unarmed victims apparently had no working radio and that race organizers had obtained Belarussian airspace permits, Belarus expressed regret and began an inquiry.

Relatives and friends remembered the victims as adventurers who had spent much of their lives in the air, often on danger's edge, Mr. Fraenckel as a pilot for the Navy in the 1960's and for T.W.A. in the last 27 years, and Mr. Stuart-Jervis as a Royal Navy flier who had been shot down in the Suez crisis and who had island-hopped for his own small Caribbean airline and was at home at the controls of seaplanes, helicopters, trainers and transports.

"He was always pushing the envelope," Caroline Stuart-Jervis said of her husband. "A few years ago at a party, someone talked about parachuting. He had never done it before, but the next day he jumped from 10,000 feet. He never passed up an opportunity for adventure."

Mrs. Stuart-Jervis, who has commuted for several years between St. Croix and Naples, Fla., where she sells real estate, said her husband had grown up in Harwich, England. During World War II, at 15, he lied about his age, joined the Royal Navy and saw action in the North Atlantic and the Far East, she said.

In 1951, still in the navy, he took flight training under American auspices at Corpus Christi, Tex., and Pensacola, Fla., and earned a commission. As an aircraft carrier fighter pilot in the Suez Canal crisis in 1956, he was shot down over the Mediterranean but was picked up by a French cruiser.

After their marriage in 1959, he went to California in a military exchange program with the United States Marines and "switched to helicopters because he was intrigued by jungle warfare," his wife said, adding: "He spent the rest of his naval career in fatigues -- in the jungles of Malaya and Borneo, fighting the Communists. He lived in the jungle for nine months in 1965."

He retired from the Royal Navy in 1968 and with his wife moved to New York, where he worked for the British Trade Development office. But a year later, Mrs. Stuart-Jervis said, the couple "discovered the island of St. Croix and liked it so much we stayed." Besides, she said, he could not stay away from aircraft for long.

Charles F. Blair Jr., a former Pan American pilot who had been the original test pilot for Sikorsky flying boats, and his wife, the actress Maureen O'Hara, were just starting a seaplane service in the Virgin Islands, Antilles Air Boats, and Mr. Stuart-Jervis became a pilot for the operation, his wife said.

In the late 1970's, she said, he began his own service, Coral Air, carrying cargo and passengers in the Caribbean. "He also had a real estate appraisal business, but didn't pay much attention to it," she said. The businesses made little money, but he became an American citizen to own them legally, she said. He also made a living teaching hundreds to fly in rented or private planes.

"His adventures never stopped," Mrs. Stuart-Jervis said. "About six years ago, he got into balloons. He met two people at a cocktail party who happened to own a balloon. That intrigued him. Next he was in South Dakota, learning how to fly one. He met Alan shortly thereafter and started competing in races."

Mr. Fraenckel, who had a home in Charlton, N.Y., near Schenectady, as well as in St. Croix, attended public schools in Scotia, N.Y., and graduated from the State University of New York at Morrisville in 1962, his cousin, Ms. Dale, said. He then joined the Navy, she said, and in the next five years became a pilot, mainly flying military transport planes.

Leaving the Navy in 1967, he joined T.W.A. as a pilot and for the last 27 years flew jetliners, mainly in trans-Atlantic service between Kennedy Airport and points in Europe.

Ms. Dale said Mr. Fraenckel became interested in balloons in 1983. "It was another way to fly," she said. His first passion was hot-air balloons, but he eventually became an enthusiast of gas ballooning, she said. While both kinds of balloons are carried by and largely subject to the wind, hot-air balloons rise on air heated with propane gas and have a more limited range than gas-filled balloons, which rise on lighter-than-air hydrogen or helium and can remain aloft for days or even weeks.

While balloon events are often called races, hot-air balloon competition involves accurate landings, while gas balloon events have more to do with distance covered. "Gas ballooning is a different ball game," she said. "There are not very many gas balloon pilots in the world."

For some, the cost of the gas is a factor. Helium, not flammable and more expensive, is widely used in the United States, while hydrogen, which is flammable and cheaper, is more widely used in Europe, Ms. Dale said.

Mr. Fraenckel, who was not married, had ballooning adventures in many lands. "He flew across Australia in a hot-air balloon for Australia's Bicentennial in 1988," Ms. Dale said. "He flew in Japan many times." For years he also entered the race named for James Gordon Bennett, publisher of the old New York Herald. He placed third in last year's event, held in the United States.

The competition, which began in 1906 and starts each year in the homeland of the previous year's winner, is for distance alone and often takes entrants over water or rugged terrain or into other dangers. In a 1923 race, five balloonists were killed by lightning; in the 1983 race two were killed.

For this year's race, Mr. Fraenckel and Mr. Stuart-Jervis formed a team, with Mr. Fraenckel as pilot and Mr. Stuart-Jervis as co-pilot.

"We had just come back from a three-week holiday in France," Mrs. Stuart-Jervis said. "He spent two nights with me. He was excited and thrilled. He knew it was a dangerous race." While there was danger, Ms. Dale agreed, Mr. Fraenckel "made no big deal of it -- he was always extremely careful."

The race, with 17 balloons, left Wil, Switzerland, on Sept. 9. Mr. Fraenckel's brother, Victor, served as ground crew, preparing the craft for launch, then following it across country in a car. But his car broke down in Poland and the balloon continued on alone into Belarus.

Then, three days out, the D-Caribbean, as the crew called it -- a skin of nylon filled with 35,000 cubic feet of highly flammable hydrogen -- fell from the sky in flames into a forest nearly a mile and a half below.

"We'd like to know why it happened, how it happened," Ms. Dale said on behalf of her family. "But we're still too numb to feel bitterness or anger."