CHICAGO - Airline passengers better get ready for a crunch this Thanksgiving week, the heaviest travel period of the year.
All the biggest U.S. airlines are in the midst of contract problems with at least one group of employees and that, combined with an expected record number of passengers and more planes crowding already busy airports, means increased potential for flight disruptions between now and the end of the holiday on Nov. 28.
''Travelers, be wary,'' says Brent Bowen, director of the University of Nebraska-Omaha's Aviation Institute.
The Air Transport Association says U.S. airlines will fly 20.5 million passengers during the period Nov. 17-28, up from a record 19.8 million during the same 12-day period last year.
The group, which represents major airlines, estimates that the Sunday after Thanksgiving will be the busiest day in U.S. airline history, with 2.24 million passengers.
The most visible turmoil again is at United Airlines, the nation's largest, which alienated millions of passengers during a summer of cancellations and delays and recently acknowledged the resumption of ''serious operational problems'' during a contract standoff with its 15,000 mechanics.
Hundreds of United flights already have been canceled this month because of what the airline maintains are unnecessary repairs by mechanics and their refusal to work overtime. The mechanics' union denies any such organized action.
Holiday passengers also will see firsthand evidence of fractious relations between United and its 25,000 flight attendants, who are distributing leaflets at selected airports to call attention to their demand for wage hikes.
The employee-owned airline is on pace to lose money for a second straight quarter after 18 profitable ones in a row.
''If United lets this drag out much longer, it could begin to be a permanent loss'' of business, says Tom Parsons of Bestfares.com, an online discount travel agency. ''Every report of delays and labor trouble hurts.''
Other airlines, which all picked up big numbers of disgruntled United passengers over the summer, are vulnerable to their own holiday hassles.
Delta Air Lines, involved in testy negotiations with pilots seeking raises like those given to United's in August, says the pilots have begun refusing overtime assignments. United blamed similar actions by its 10,500 pilots for much of last summer's chaos.
Chances of immediate problems lessened Friday, however, when the two sides agreed to take their talks to federal mediation.
Northwest Airlines is at odds with its mechanics union, which recently went to court and accused it of bargaining in bad faith after four years of fruitless contract talks. US Airways pilots filed a grievance over the airline's pending merger with United, although no slowdown is expected at this point. American Airlines' flight attendants are dissatisfied with their contract.
Pilots at Continental Airlines, eyeing the United pilots' average 24.5 percent wage hikes, asked last week that their contract be renegotiated even though it doesn't expire until 2002.
The holiday rush started with harsh undertones Friday when United went to federal court in Chicago and obtained a temporary restraining order against alleged work slowdowns by its mechanics.
A day earlier, the carrier declared an operational emergency at Denver International Airport and at Chicago's O'Hare International Airport to force mechanics to work extra hours.
The get-tough moves appeared to signal that no settlement with the mechanics is imminent. The bigger goal for the airline, industry analysts say, may be to clear up its labor woes by year's end to remove potential roadblocks to its $4.3 billion merger.
That's of little comfort to Thanksgiving travelers.
''The traveler that United needs to worry about the most isn't the leisure traveler, it's the business traveler who's paying $2,000 a ticket,'' says Parsons. ''The business traveler might give them all the way through Christmas to straighten their problems out. But they've got to settle them soon.''
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