ENTHUSED ENTREPRENEURS BEAR WITH FLIGHTY NATURE OF START-UP AIRLINES.

Byline: Adam Bryant The New York Times

Mark W. McDonald felt like a man accursed. Almost from the day he began to challenge giant USAir in the Northeast with his new airline, Nations Air, bad luck always seemed to strike on Fridays.

But nothing had prepared the 36-year-old entrepreneur for the disaster born on Friday, Oct. 6.

On that day, the company that leased both planes for his fledgling carrier's fleet tried to call McDonald to discuss a routine matter. But because Hurricane Opal had knocked out phone service for parts of Atlanta, all that Viscount Air Services heard was a recording saying that the phones were out of order.

Viscount mistakenly assumed that Nations Air Express Inc. had gone out of business - a reasonable enough conclusion, given the low success rate for start-up carriers. Fearing that its planes would be tied up in bankruptcy proceedings, Viscount dispatched two pilots to Pittsburgh to take back the one plane that was not undergoing heavy maintenance. At 2:30 Saturday morning, while McDonald slept in his home in suburban Atlanta, the Viscount pilots flew off with his company's only working plane.

"This," said McDonald, spinning out his misadventures in a recent interview, "is a suicidal business."

No kidding. But for all that can go wrong in the thin-margin, capital-hungry, labor-intensive and highly regulated airline industry, it still manages to attract entrepreneurs. Since 1990, 46 applications have been filed to start new airlines, and the pace is accelerating, the Transportation Department said.

Indeed, most airline entrepreneurs say they can not imagine doing anything else. "There is something about a business that puts 100 people in an aluminum tube and pushes them through the air at 400 miles an hour," said Robert J. McAdoo, the former chief financial officer of People Express who, after a stint as a Wall Street analyst, started Vanguard Airlines, a small airline based in Kansas City, Mo., in 1994.

Whatever the motivation, the big winners are consumers. The Transportation Department estimates that low-fare carriers save American travelers about $4 billion a year. Even big, established airlines benefit, it says, because they are forced to be more efficient and are thus better equipped to weather cyclical downturns.

The losers are usually the new entrants. Indeed, starting an airline often winds up unintentionally being an act of altruism. Since the industry was deregulated in 1978, ushering in an age of brutal competition, about 100 airlines have filed for bankruptcy, some more than once, according to the Air Transport Association, an industry trade group.

There are rare success stories. For instance, Valujet Inc., based in Atlanta, went public in June 1994 at $12.50. Those shares - two-fifths in the hands of the airline's founders and top executives - are now worth more than $100 after adjusting for two 2-for-1 stock splits.

But Valujet is the exception, not the rule. And McDonald, who is still in business despite all his bad Fridays, knows the rule all too well: For a newcomer in the airline industry, being blind-sided is practically part of the daily routine.

McDonald was aware of the risks long before he took the plunge. Flying, though, is the only profession he has known, he said, since giving up a high-school passion for motocross riding to take it up.

His first business venture prospered: a charter airline carrying both passengers and freight, which he started in 1987 in Miami. By the time he was 33, he said, he was well on his way to earning his second million. But he needed a new challenge.

"It's something that just gets in your blood," he said. "I go to sleep sometimes at night wondering why I'm in this business, but then wake up and I can't wait to get to work."

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CHART[ordinal indicator, masculine]PHOTO

Photo Mark McDonald sits in his office at the Nations Air's corporate headquarters in Marietta, Ga. The New York Times Chart Struggling to Fly