US Airways is suing its pilot union, claiming that the pilots are engaging in a campaign to slow down work and cause flight delays.

In the lawsuit, Tempe, Ariz.-based US Airways claims that operations at the Charlotte/Douglas International Airport, which is the airline's busiest hub, have been "dramatically impacted" with an increase in delays and passengers' baggage not reaching connecting flights.

"This is not a step we take lightly, but we simply can no longer allow the labor union's illegal and misguided actions to harm US Airways, our employees and our customers," US Airways CEO Doug Parker said in an email to employees.

Two union officials could not be reached by phone late Friday.

The two sides have been locked in a bitter labor dispute for more than six years, unable to reach a new contract following a 2005 merger with America West.

Pilots claim the company is trying to keep them locked in bankruptcy-era wages that reflect deep cuts made to keep the airline afloat. The airline insists that giving the pilots their terms would shatter the company's fragile financial health.

In the lawsuit, US Airways called the U.S. Airline Pilots Association's actions "an ongoing unlawful pilot slowdown campaign."

Steve Johnson, a US Airways executive vice president for legal affairs, said that the company hopes for an expedited ruling from the federal court in Charlotte.

US Airways is seeking an injunction directing the union to tell pilots not to engage in any slowdown activity. That would allow the airline's operations to quickly return to normal, Johnson said.

This is not the first time a major airline has sued its pilot union.

In 1999, American Airlines won a US$45 million decision against the Allied Pilots Association after an 11-day "sickout" led to the cancellation of nearly 6,700 flights.