At least this time it didn’t happen on the plane. Spirit Airlines is in the middle of a legal fight with its pilots, but yesterday afternoon found itself in the middle of an actual fight in the Fort Lauderdale airport. The airline had canceled nine flights and could not rebook anyone for hours, and eventually the tensions broke out into a brawl between passengers:

Sheriff’s deputies were forced to step in at Fort Lauderdale-Hollywood International Airport overnight when passengers became upset when Spirit Airlines canceled nine flights. …

Upset passengers began to fight near the crowded Spirit Airlines check-in counter Monday night.

“Very angry angry angry people – everybody had places to be and couldn’t be there,” said Debbie McGrandy, who was fresh off of a cruise and struggling to get back home to Detroit.

“This is actually our third Spirit flight that has been canceled since Thursday. I slept in the airport in Philly already on Thursday night and I don’t want to sleep in an airport again tonight,” McGrandy said.

According to Spirit, the fault belongs with its pilots, whom they accuse of conducting a work slowdown over a contract dispute. The pilots deny that they are conducting any kind of job action, but the airline filed suit against the pilots’ union anyway, asking for injunctive relief under the Railway Labor Act:

In its suit, Spirit said the Air Line Pilots Association (ALPA) and some of its members are “purposely and unlawfully disrupting the airline’s operations.” Spirit suggested the effort was an attempt by the union to affect contract negotiations.

“We are disappointed that ALPA has decided to engage in this unlawful slowdown,” Spirit spokesman Paul Berry said in a statement to USA TODAY’s Today in the Sky blog. “This has led to canceled flights and prevented our customers from taking their planned travel, all for the sole purpose of influencing current labor negotiations. So we reluctantly filed this suit to protect our customers’ and our operations.”

“This is clearly unlawful activity under the Railway Labor Act, which governs labor relations in the airline industry,” Berry added in the statement. “ALPA and those individuals responsible should be held accountable.”

The CBS report notes one curious argument in the suit, however. According to their filing, Spirit says they are relying on a “status quo” of overtime work from its pilots. If they are working without a contract, then there may not be any legal requirement to work overtime. If pilots are refusing the OT, then that would explain why Spirit is short on flight crews — and it seems doubtful that a court will force pilots to fly overtime to cover Spirit’s schedule, Railway Labor Act notwithstanding. That raises other questions about Spirit’s business model, and might not necessarily be something that will add luster to an already no-frills carrier.

This brawl should get both sides back to the table ASAP on that point alone. Spirit doesn’t necessarily make its money on a customer-service model, but its lack of frills makes reliability even more important. The money saved up front isn’t worth the risk of the disruptions in travel that this dispute is causing, let alone the brawls at the counter. If the two sides don’t resolve their differences soon, both may find that they have nothing left to fight over.