But there is a lively debate about whether the consolidation of two big airlines into one megacarrier under the name of Delta or the relentless rise of fuel prices - an airline's biggest expense - will be to blame for the rise.

"There's so much upward pressure coming from the increase in fuel that any pressure on fares from the consolidation would be imperceptible," David Stempler, president of the Air Travelers Association, said Tuesday.

Monday's agreement by the boards of Delta and Northwest to OK a union of the No. 3 and No. 5 domestic airlines includes a pledge not to add to previously planned reductions in domestic capacity.

But that's where analysts see a conflict because of pressures from Wall Street on the airlines to lower costs and raise revenues. "They need to raise fares, and to do that, seats need to come out. Delta and Northwest aren't doing that," said Kevin Crissy of UBS Securities.

Wall Street investors already being cool to the deal, which would create the world's largest carrier in terms of passenger travel, because of worries that the consolidation won't create savings to offset fuel costs. On Tuesday, they punished the stocks of both airlines, and two of Northwest Union's also signaled their opposition.

To pay their fuel bills, the nation's airlines have attempted 11 fare increases since early January, seven of which have stuck. Since that time, passengers are paying an average of $130 more per ticket, a figure that could rise to $160 by the end of May, said Rick Seaney, president of Farecompare.com, a consumer airline ticket research Web site.

Absent rising crude oil prices, which closed at a record $113.79 a barrel Tuesday, fares probably would not budge because of the merger, Seaney said.

That's because only 12 of more than 1,000 nonstop routes flown by Delta and Northwest dovetail, he said. "So they don't compete, and competition is what drives prices."

Delta and Northwest officials went to great lengths Tuesday to dispel the idea that consolidation could harm competitors and drive up fares. Delta CEO Richard Anderson told reporters in Atlanta that there are ''no competitive issues'' on domestic routes.

But if this merger kicks off a wave of airline consolidation, other analysts say that fewer carriers in the sky will lead to higher fares. Bob McAdoo, a former airline chief financial officer and analyst with Avondale Partners, said he expects consolidation to also end fire sales for discount tickets because there will be fewer surplus seats.

Still, airports that are also served by low-cost carriers such as Southwest Airlines probably will continue to keep prices low, McAdoo said. ''The low-cost carrier is the guy who sets the prices."

Although many fares are certain to rise, the pain probably will be felt most by passengers flying to or from regional airports, where fares are already three to four times greater than at bigger airports, said Tom Parsons, publisher of Bestfares.com, a travel Web site that monitors ticket prices.

"Business travelers will pay a lot more, especially on noncompetitive routes, as will leisure travelers who fly to airports not served by low-cost carriers."

Although Delta hasn't detailed plans for its Salt Lake City hub, some analysts speculate that Delta might boost operations here to take advantage of its Western location. On Monday, Delta said Salt Lake City will continue to be the airline's primary gateway to Western destinations and that local travelers would have better access to Asia, where Northwest is strong, as well as to Delta's rapidly growing European market.

"Salt Lake may have at least as much value to the merged carriers and possibly more," said George Hamlin of the consulting firm Airline Capital Associates.

He said its possible the merger could open up trans-Pacific flights from Salt Lake City, a notion being discussed by some of Delta's 600 Salt Lake-based pilots.

That isn't dismissed by Delta executives, who say the merger will permit the combined airline to look at routes that Delta and Northwest could not tackle separately.

"Those are the kind of opportunities that we will be looking at," Glen Hauenstein, Delta's executive vice president of network planning and revenue, said Tuesday. "Salt Lake provides a very unique geography in the world's largest aviation network now. You have one of the hubs of the world's largest carrier, and that's a cool thing, I think."

Stempler said more routes to Europe from Salt Lake than the one Delta will launch in June are also possible.

"I can certainly see more European flying, with [travelers from around the West] feeding into Salt Lake."

---

* THE ASSOCIATED PRESS contributed to this story

Source: U.S. Department of Transportation's Bureau of Transportation Statistics