USAir Struggles With a Reversal of Fortune : Aviation: The firm, which blossomed from regional status, is in retreat. It will soon halt most flights in California.

USAir, which blossomed over the years from a small regional carrier into the nation’s sixth-largest airline, is now a company in retreat.

Last week, the carrier, which is based in Arlington, Va., announced that it will cut most of its flights within California, abandoning its plans to be a major power on the West Coast. It also is likely to mean the loss of roughly 500 jobs in the state.

In August, USAir furloughed 3,600 workers across the country, one of the biggest job cutbacks recently in the hard-hit airline industry.

Meanwhile, SkyWest, the owner of the commuter plane that collided with USAir’s Boeing 737 on Friday, is one of the nation’s largest regional airlines. Based in Utah, it operates most of its flights from Salt Lake City and airports in Southern California.

Under an agreement with Atlanta-based Delta Air Lines, it operates as “the Delta Connection,” bringing customers from regional airports such as Palmdale’s to major hubs where Delta lands.

In the fiscal year ended March 31, SkyWest’s parent company reported profits of $4.72 million on revenues of $99.7 million.

USAir, on the other hand, is trying to stem big losses resulting from, among other things, service problems, difficulties from past mergers and fare wares among the major air carriers. More recently, tensions in the Persian Gulf have worsened matters by boosting fuel costs and raising fears of terrorism, prompting many people to scrap their travel plans.

USAir reported eight days ago that its losses widened to $221.1 million in its fourth quarter on revenues of $1.66 billion. In the same period a year earlier, it lost $101.7 million on revenues of $1.5 billion.

For 1990, USAir’s losses skyrocketed to $454.5 million on revenues of $6.56 billion, after a loss of $63.2 million on revenues of $6.24 billion in 1989.

As part of its turnaround effort, the company announced last month that Seth E. Schofield would succeed the retiring Edwin I. Colodny as chief executive in June.

In California, USAir will pull out of six airports on May 2: Burbank, Ontario, Palm Springs, San Jose, Oakland and John Wayne in Orange County. It will continue to fly from Los Angeles, San Francisco, San Diego and Sacramento, but most of the remaining flights will be to locations outside of California.

The airline also is halting service to Portland, Ore. The cutbacks in the West largely undo USAir’s 1986 purchase of Pacific Southwest Airlines.