Spirit Airlines and its striking pilots agreed to meet with mediators today, the union said, signaling a potential thaw that would be welcomed by the thousands of customers holding tickets on the grounded airline.

Sean Creed, head of the pilot union at Spirit, said that the National Mediation Board has asked both sides to meet in Fort Lauderdale, Fla.

Spirit said that it wouldn't fly until Thursday at the earliest, forcing its roughly 16,000 daily passengers to get where they were going by rental car or an expensive walk-up fare on another airline. Spirit carries just 1 percent of the nation's air traffic, but those travelers have been 100 percent grounded by the pilot walkout.

Spirit is usually the biggest carrier at Atlantic City International Airport. Yesterday, two of Spirit's planes sat idle on the ramp, and only a few people were near its ticket counters.

The airline is offering customers credit for future flights, plus $100. But if they want refunds instead, customers have to request that from the airline.

Pilots have said that their pay should be similar to other discount airlines' like JetBlue Airways Corp. and AirTran Airways, a unit of AirTran Holdings Inc. The company has said that those other airlines are much bigger than Spirit.

Lee Maron said that she was forced to rent a car to get home to Boston after flying to Atlantic City for a bar mitzvah. She was unimpressed by the voucher for future travel on an airline that she predicted wouldn't be around for long.

"Giving me a voucher and a credit for something that won't exist is like getting a bad Christmas gift," she said.