May 29 (Reuters) - A union representing about 4,100

flight attendants at Frontier Airlines on Wednesday filed for

federal mediation over the carrier's plan to overhaul its

operations.

Frontier has announced plans to rework its network to allow

almost all of its planes to return to their stations every

night. The so-called out-and-back model inspired by European

budget carriers is meant to minimize flight cancellations and

delays. The Association of Flight Attendants-CWA filed with the

National Mediation Board seeking bargaining over the change that

it says "is causing a dramatic reduction in compensation while

sharply increasing time on the job or commuting to it."