Delta Air Lines raised many of its high-end, last-minute tickets by $4 to $10 per round trip.
The airline confirmed the increase on Tuesday. Other carriers said they had not matched it, but didn't rule out a fare hike.
On Monday night, Delta raised most of tickets sold with seven days of the trip, including first-class, instant-upgrade, and unrestricted economy-class seats that are usually preferred by business travelers. Tickets that must be bought 14 or 21 days in advance were not affected; those seats usually cost less and appeal mostly to leisure travelers.
It was the first major price increase attempted since United Continental boosted fares on most of its domestic seats by $10 per round trip two weeks ago. United rolled back its increase after Southwest Airlines declined to match it.
Jamie Baker, an analyst for JPMorgan Chase who closely tracks airfares, said Delta may believe that an increase aimed at higher-priced seats stands a better chance of sticking even if discount airlines decline to go along.
Southwest, United, American Airlines, US Airways, JetBlue Airways, and Virgin America said as of Tuesday afternoon they had not raised prices.
Airlines raised base fares about a dozen times as jet fuel prices climbed in 2011 and early 2012. But the pace of fare increases slowed this spring as fuel prices fell and the economy remained weak. Meanwhile, the airlines frequently undercut the increases by running sales. Southwest launched a new one Tuesday.