Pilots at Spirit Airlines struck the company on Saturday after mediated contract talks failed to reach an agreement, a small-carrier stalemate that could influence workers at bigger carriers.
The strike at privately held Spirit was the first notable job action at a U.S. passenger airline since Northwest Airlines mechanics walked off the job in 2005.
All Spirit flights for Saturday were canceled.
Spirit's 430 pilots are represented by the Air Line Pilots Association (ALPA), which could not bridge differences with management over pay, benefits and scheduling.
Airline unions across the industry are watching the Spirit talks closely as many groups are in active contract negotiations or getting ready to begin talks.
With U.S. airlines on stronger financial footing, unions are eager to recapture pay and benefits lost during the industry's drastic restructuring from 2002-07. Spirit is profitable, helped partly by low labor costs.
Airline strikes, due to the importance of the industry to U.S. commerce, are permitted under federal law only after mediated talks fail to produce an agreement.
In the case of Spirit, pilots were free to strike following a month-long cooling off period, which expired on Saturday. Last-ditch talks did, however, occur over the past week.
Mediators can request that the White House appoint a special board to stop the strike for up to 60 days and recommend a new contract. Previous presidential administrations took that step in some cases, reasoning that those airline strikes would have resulted in serious economic disruption had they been allowed to continue.
Spirit, based in Miramar, Florida, offers flights in the United States, Latin America and the Caribbean. The carrier has vowed to help its passengers get on other airlines.
(Reporting by John Crawley and Karen Jacobs; Editing by Eric Beech)