Aug 28 (Reuters) - Flight attendants at United Airlines

have voted in favor of a strike authorization, the

Association of Flight Attendants-CWA said on Wednesday.

Over 90% of the flight attendants participated, with 99.99%

of the votes in favor of a strike authorization, the union said.

It is the first time since the 2005 bankruptcy

negotiations that flight attendants at United voted on strike

authorization, it added.

Over 28,000 flight attendants of the Chicago-based

carrier affiliated with the AFA have been negotiating for a

double-digit base pay increase and higher pay for time at work -

including on-ground duties, retroactive pay, schedule

flexibility and work rule improvements.

"As Labor Day travel begins, United management is

reminded what's at stake if we don't get this done," said Ken

Diaz, president of the United chapter of the AFA.

The situation unfolds amid

new contract negotiations

in the U.S. and Canada, where cabin crews at carriers are

also seeking compensation for on-ground duties such as boarding

passengers and waiting between flights.

Last year, United's flight attendants filed for federal

mediation through the National Mediation Board (NMB).

The union added that it can now request a release from

the NMB leading to a 30-day "cooling off" period and strike

deadline.

Even though the strike is authorized, the flight

attendants cannot walk off the job until they're granted

permission from the board after it determines that both parties

are at a standstill and further negotiations would not be

productive.