By mid-afternoon, Northwest had canceled about 12 percent of the day's flights, according to FlightStats, an online service that tracks airline performance. FlightStats said Northwest canceled about the same percentage of its flights on Monday.
FlightStats spokeswoman Mera McLaughlin says Northwest's cancellation rate is running five to six times that of other airlines.
"FlightsStats is not at this point presuming to say why they are canceling. But we are able to quantify there are a very high number of cancellations. They seemed to be centralized in the Detroit and Minneapolis areas," she said.
About 8 percent of Northwest flights out of the Twin Cities had been canceled as of early Tuesday afternoon. In Detroit, 18 percent of departures had been canceled. Flightstats says Northwest canceled six flights from Chicago's O'Hare Airport -- about one quarter of scheduled departures.
"No one else seems to be having the same trouble and we're not seeing significant weather patterns that would seem to indicate weather incursions on these flights, according to McLaughlin.
For its part, Northwest said that about 11 percent of flights on its mainline jets -- those are the big planes -- had been canceled from Friday to Monday.
The airline blamed the cancellations on several factors, including air traffic control restrictions, severe weather and a higher than normal level of pilot absenteeism.
"It clearly is a labor dispute," suggested Minneapolis-based travel expert Terry Trippler.
"Yes, there can be mitigating circumstances, such as weather problems a couple of weeks ago," Trippler said. "And maybe some crew fatigue and what have you. But the bottom line is that this is a labor situation."
Trippler suspects pilots are not flying as much as they could, forcing Northwest to cancel flights. The pilots' contract calls for them to fly up to 90 hours a month. But Trippler says federal rules would allow them to fly as many as 100 hours a month.
Northwest's pilots say management is to blame for causing many recent flight cancellations. The Air Line Pilots Association says there aren't enough pilots scheduled to fly the summer schedule. On June 15, the pilots' union executive council passed a resolution expressing "no confidence" in Northwest's management because of fears that an operations meltdown was looming. "It's a staffing issue," said pilot union spokesman Monty Montgomery. "We saw this coming and we warned them about it. But as of yet, they have not reacted to it."
Montgomery says pilots are too worn out to fly more. He notes that they spend a lot more hours working than the time they're actually in the air, which is what's counted.
"Our pilots are tired. They're been going at the red line for some time now. Most of them are reluctant to pick up more time because they're worn out," he said.
Northwest is relying on fewer pilots to fly more hours. The union says Northwest now has about 20-percent fewer pilots than the airline had seven years ago. But in their latest contract with Northwest, the pilots agreed to increase their monthly flying maximum by about 13 percent.
Dana Gilbert hopes Northwest stops canceling so many flights. She's getting married Sunday, and she's worried about guests who plan to fly to the Twin Cities for the wedding.
"Some of them have plans to fly in on Saturday. And the wedding is on Sunday. So, if something happens and their flight is canceled and they can't get them out until Sunday, they won't really be able to come to the wedding," Gilbert said. "We already know of people whose flights have been canceled who were supposed to come on Thursday. And now they're not coming until Friday. So, it is playing havoc with a lot of our guests travel plans."
Northwest says it is relaxing travel restrictions to help ensure rebookings as quickly as possible.