United to Raise Fares on Many U.S. Routes : Airlines: So far, only TWA is matching the increases. Analysts say the new price structure may fall apart if other carriers don’t follow suit.

United Airlines, the second-biggest U.S. airline, said Tuesday that it is raising fares on a broad range of domestic flights and rival carriers said they may follow suit.

Trans World Airlines Inc. alone matched the hikes immediately and analysts said that if just one big carrier opts to stick with present fares, the revenue-raiser will collapse.

United said it plans to raise full-fare, one-way first class tickets by $8 and full-fare, one-way coach tickets by $5 in most of the 48 continental states beginning Nov. 30.

Chicago-based United, a subsidiary of UAL Corp., also said it is raising prices by $5 on its discounted one-way tickets that require three, seven and 14-day advance purchases.

But the increases, which were fed into United’s computer reservation system over the weekend, are aimed chiefly at business travelers and do not apply to the excursion fares the vast majority of leisure travelers use.

Excursion fares, also known as Maxsavers, typically require round-trip travel, a Saturday night stay and 14-day advance purchase.

Of United’s competitors, only Trans World Airlines said it has decided to match the increases, and did so selectively.

TWA raised its full-fare coach and first class one-way fares by the same margins as United but left its advance-purchase fares untouched.

Delta Air Lines Inc., USAir Group Inc., AMR Corp. and Eastern Airlines, a subsidiary of Texas Air Corp., all said they are studying United’s move and have not yet decided whether to match it.