Airlines to Raise Fares on Some Routes : Competition: Most rates will rise $10 to $40, some will go up $50 or more, but others won’t see any increase.

The nation’s major airlines said they will raise fares today between $10 to $50, after previous attempts to boost prices failed because of stiff competition in the ailing industry.

American Airlines, Delta Air Lines, United Airlines, Trans World Airlines, Continental Airlines, USAir and America West Airlines all said Thursday that they planned to go ahead with scheduled increases--delayed as recently as last week.

“This is a return to what we think are sensible levels for both the industry and the public,” said Tim Smith, a spokesman for American, the nation’s largest carrier, adding that “in the long run, no industry can continue to price its product at below cost.”

The new fares will be based on miles traveled rather than the popularity of a particular run between two cities.

The fare increases were expected to mark the end of a summer that saw big fare cuts and packed planes but also huge losses for the nation’s air carriers.

“Let’s certainly hope so, because it was disastrous for all of us,” Delta spokesman Neil Monroe said.

The discounting helped raise airplane loads from 68% in July, 1991, to 73% this July, but the industry still lost $668 million in the first six months of 1992, according to the Air Transport Assn. That followed losses of $2.4 billion in 1990 and $1.6 billion in 1991.

“We believe it’s necessary to have a price increase. We believe that it makes business sense,” said Don Fleming, a TWA spokesman.

Previously announced increases that were never implemented would have hiked fares as much as 33% higher. They didn’t hold up, however, because one airline or another refused to go along at the last minute to maintain a competitive edge.

The new fare realignment “is intended to make fares relate more closely to distance traveled,” said Ned Walker, a Continental spokesman.

While most fares will rise between $10 and $40, some longer runs will go up $50 or more, and some markets won’t see any increase in prices.

For example, round-trip excursion fares on Continental between New York and Detroit will rise from $220 to $230. The round-trip fare from New York to Los Angeles will increase from $390 to $440, while the price of a round-trip from Boston to Denver will remain unchanged at $430 on Continental.

“The formula is being restructured to represent a closer adherence to distance, to mileage, and also to bring it up to mid-April standards when there was a previous restructuring,” said Delta’s Monroe.

“So if you’ve got a route where the fare hasn’t been changed and it fits in the mileage formula, then there won’t be an increase--and there’ll be a lot of those markets,” he said.

United’s Joe Hopkins said the increase will affect about two-thirds of the Chicago-based carrier’s domestic markets, raising prices in most cases, between $10 and $30. “So in one third of our markets, the fares will stay where they are,” he added.

American’s Smith said the Ft. Worth-based carrier will match United’s prices rather than the slightly higher Continental fares.

At USAir, round-trip excursion fares on most domestic flights will go up an average of $10 to $30, with a $50 cap on any increases in one-way fares for business travelers, said spokesman David H. Shipley.

The increases bring fares back up to the levels on April 13, when a fare overhaul initiated by American went into effect. Under that system, fares for leisure travel stayed the same or rose, but fares for last-minute travelers dropped.