A union representing US Airways Group Inc. pilots on Sunday rejected the carrier's accusations that it was encouraging an illegal work slowdown, resulting in more flight and baggage delays and increased cancellations.

US Airways had on Friday filed a lawsuit in the U.S. District Court in Charlotte, North Carolina, seeking to halt an "unlawful pilot slowdown campaign" designed to put pressure on collective bargaining talks.

But union spokesman Capt. James Ray called "categorically false" the Tempe, Arizona-based carrier's accusations that the union is involved in any illegal job action. He also said US Airways is trying to portray the union's efforts to address "legitimate safety concerns" as a mere negotiating tactic.

"The US Airways lawsuit represents nothing more than an escalation of the pilot intimidation campaign that started more than three years ago when they tried to discipline pilots for requesting additional reserve fuel," he said.

US Airways spokeswoman Tina Swail declined to comment on Ray's statement.

The carrier and the union, which said it represents 5,200 pilots, have been in often contentious contract talks since the 2005 merger of the old US Airways with America West Airlines.

A dispute over seniority has been the main stumbling block to a joint labor agreement with pilots from both carriers.

Pilots from the old US Airways fly mainly in the eastern United States, while former America West pilots fly mainly in the West. Talks are in mediation.

More Bags Left Behind

In its lawsuit, US Airways accused the union of encouraging pilots to do their jobs more slowly, delay departures, refuse to fly because of fatigue, increase "maintenance write-ups" and not complete required training, and to "expose and retaliate" against pilots who do not join the slowdown.

It said the job action has since May 1 caused more flight delays, and nine or 10 daily cancellations affecting more than 105,000 passengers, on planes flown by pilots who worked for US Airways before the merger.

These pilots have "generally stronger" allegiance to the union than former American West pilots, the carrier said.

US Airways also said the rate at which passengers' bags do not make it onto connecting flights at Charlotte, one of its hubs, has since May 1 risen by more than five bags per 1,000 connecting passengers. That's an increase of 45 percent from the historical average of 11.59 bags per 1,000, it said.

On July 22, the union placed a full-page advertisement in the USA Today newspaper accusing US Airways of not doing enough to ensure safe aircraft.

US Airways shares closed Friday at US$6.24.

The case is US Airways Inc v. U.S Airline Pilots Association et al, U.S. District Court, Western District of North Carolina, No. 11-00371.