If US Airways and United Airlines merge, whichever management team lands in the pilot's seat could produce dramatically different outcomes for the Pittsburgh area.

"I think Pittsburgh would be a ghost town" with United in charge, said Bill Freiberger, general chairman with the International Association of Machinists and Aerospace Workers, District 142.

United, Mr. Freiberger noted, already outsources all of its mechanical work and thus would have no need for the 400 to 500 unionized mechanics who work on 737s, 757s, A319s and A320s in Moon near Pittsburgh International Airport. US Airways, in its heyday here, once employed 3,000 local mechanics.

A much better scenario for the region could result if US Airways Chief Executive Officer Doug Parker is the one calling the shots, Mr. Freiberger said. At a meeting last week in Tempe, Ariz., Mr. Parker told union officials that if a merger with United were to happen (he spoke in the hypothetical and did not confirm ongoing talks), the CEO would handle it differently than the 2005 union of the old US Airways and American West Airlines -- a combination still hampered by labor integration problems. Instead of waiting years for workers from rival airlines to hammer out a single contract, he said he would automatically grant the highest-cost contract among the two, according to Mr. Freiberger.

"Labor support and labor peace -- I think that's exactly what he's looking for going forward."

In the case of mechanics at US Airways and United, the higher-cost contract belongs to US Airways, Mr. Freiberger said. It not only requires that Pittsburgh and Charlotte, N.C., remain open as maintenance bases, but it also requires a 50-50 split between outsourced and in-house work by unionized workers. The addition of United's larger fleet would require a lot more mechanics on site in Pittsburgh and Charlotte, Mr. Freiberger said, as well as the possible re-opening of a large United maintenance base in San Francisco.

Neither airline has confirmed reports suggesting that a deal is imminent, but that has not stopped unions from expressing reservations about the idea.

United's pilots said the merger with US Airways should be a "last resort" and the "chaotic labor situation " at US Airways would make any integration difficult and less likely to produce cost savings. Flight attendants from both carriers called the merger discussions "foolhardy." The IAM has urged lawmakers to resist approvals for new airline consolidation and argued for "limited" re-regulation of an industry that was deregulated in 1978.

Many analysts agree a US Airways-United combination could mean cost savings for the new carrier but also capacity cuts, closure of hubs, job losses and possibly higher fares. Southwest Airlines' boss Gary Kelly said he welcomes the merger because it provides him with an opportunity to seize more market share in places such as Pittsburgh, where the Dallas-based carrier has expanded in recent years.

Pennsylvania's U.S. senators Bob Casey and Arlen Specter wrote a letter to Mr. Parker last week urging him to maintain Philadelphia's status as a key East Coast hub and asking that current service in Pittsburgh "not be significantly altered in the event of a merger."

"While we remain concerned about US Airways' recent reduction of daily flights out of Pittsburgh," they wrote, "we are encouraged by a recent statement by company President Scott Kirby in which he indicates that 'we have no plans to make further cuts in Pittsburgh.' Should US Airways decide to merge with any other airline, we expect that any merged entity will honor this commitment."

US Airways currently operates about 71 flights a day at Pittsburgh International, down from 542 before 9/11.

It is also building a new operations control center nearby, at a cost of $25 million, for 600 employees. US Airways decided to build the control center here instead of Phoenix or Charlotte in part because of $16.25 million in public incentives. The building is under construction and scheduled to be completed later this year.

Asked if he were concerned about the fate of the control center in the event of a merger (United has a control center in Elk Grove, Ill.), Allegheny County Airport Authority Director Bradley Penrod said, "I think it's too early to know what's going to happen."