US Airways filed a petition in federal court in Charlotte today asking a judge to quickly put an end to what it claims is an illegal pilot slowdown causing flight delays and cancellations.

The U.S. Airline Pilots Association has denied any organized slowdown is taking place, and says US Airways is ignoring safety concerns to get planes in the air on time. The union also says US Airways is trying to force pilots to fly unsafe planes rather than repair them.

Today's court filing is part of a lawsuit that US Airways originally filed in late July. The company claims that the pilots are dropping trips, writing up unnecessary maintenance items and outing pilots who refuse to participate to their fellow employees, as part of a campaign to pressure the company in contract negotiations.

"The current situation is untenable for US Airways, the traveling public, and the pilots who refuse to accede to the threats and intimidation," the airline said in its filing Monday.

US Airways originally asked for an expedited hearing schedule, but claims that it has been unable to reach any agreement with USAPA's lawyers. The union must file a response to the company's suit by Monday, Aug. 15. But US Airways claims USAPA has indicated that it might need until the beginning of September or later to file a full response.

The company is asking the court to for a temporary restraining order directing the union to stop the alleged slowdown. A hearing is set for Friday morning in federal court in Charlotte.

The dispute stretches back to US Airways' 2005 merger with America West. The pilot groups were unable to agree on a combined seniority list, spawning a bitter internal dispute. Contract negotiations have dragged on ever since, with the union and management both calling each other's position unrealistic.

US Airways operates some 630 flights at Charlotte/Douglas International, about 90 percent of the airport's total. Charlotte's airport is the company's busiest hub, and there are some 6,900 US Airways employees based here.

Since filing its lawsuit on July 29, US Airways claims the alleged union slowdown has continued. An average of nine or ten flights a day have been cancelled as a result, stranding some 11,000 passengers, US Airways claims. In its lawsuit, US Airways alleges that more flights are being delayed by tactics such as slow taxiing and unnecessary maintenance write-ups.

The airline also claims that pilots are being intimidated if they don't comply. Emails obtained by the company, US Airways says, identify pilots seen as not helping with the union's effort by name and position. One email sent Thursday allegedly called such pilots names including "whore" and "back stabbing piece of monkey ****."

USAPA has repeatedly denied the company's accusations, and a spokesman has said the union doesn't support a slowdown and has told pilots so. The union also recently sued US Airways in federal court, accusing the company of deliberately dragging out negotiations.

The union says the company is ignoring safety and maintenance concerns and rushing pilots to get planes flying, as well as engaging in a long campaign of discipline and intimidation to get pilots in line.

Contract negotiations with the union have been under federal mediation for more than a year. Under federal law, neither side can take any action to change the status quo - such as a strike - until after a mediator declares negotiations are at an impasse.Researcher Maria David contributed.