US Airways is asking for 400 flights attendants to volunteer for leaves of up to 16 months, and said involuntary furloughs could be next if there aren't enough takers.

The Tempe, Ariz.-based company said in a newsletter issued to workers on Thursday that it needs fewer flight attendants because it has reduced capacity faster than flight attendants have retired or quit. Many individual flight attendants are flying more than they used to, leaving the company with too many reserve flight attendants, it said.

US Airways is seeking 300 volunteers from its hubs in Phoenix and Las Vegas and 100 volunteers based on the East coast. The Western flight attendants are from America West, which bought US Airways in 2005, while the flight attendants in the Eastern cities came from the old US Airways.

The voluntary furloughs range from 6 months to 16 months for the Western flight attendants and 3 months for the Eastern flight attendants, said Mike Flores, president of the Association of Flight Attendants unit that represents the original US Airways workers.

The newsletter said the difference was because the biggest capacity cuts have been from Las Vegas and Phoenix.

"We have waited as long as we could to address our overstaffing situation hoping that attrition and other voluntary leave options would offset the need for today's action," said Hector Adler, vice president for in-flight services, in the newsletter.

The company said it has eliminated 1,300 positions among pilots, ground workers, and managers over the past year because of the slowdown.

Airline president Scott Kirby said at an industry conference Thursday that the company's current decline in passenger revenue is even worse than the decline that followed Sept. 11.

Shares of US Airways Group rose 4 cents to close at $2.71 on Friday.