The way the Thomsons read their insurance plan, they thought any emergency medical transportation was covered.

But it turns out, the air-ambulance company was out of their network, and they got a bill for $56,000.

“Coming back and looking at that bill and thinking you’ve got to be kidding me,” Thomson said. “Here is the flight that ultimately saved Isla’s life by getting her to where she needs to be. And yet [it] is going to put us potentially in financial ruin. Or at least kill our future dreams as a family.”

When patients need an air ambulance, the first priority is getting them the care they need as fast as possible. So, patients don’t always know who is going to pick them up or if the ambulance is an in-network provider.

That can lead to surprise expenses if the companies ask patients to pay the bill or any balance left after the insurance plan’s out-of-network coverage is applied.

“Of all the complaints we have received in our office, not one person was uninsured,” said Jesse Laslovich, the legal counsel for Montana’s insurance commissioner. “They’re all insured. And they are frustrated as heck that they’re still getting $50,000 balance bills.”

States can regulate some medical aspects of air ambulances, but federal laws prevent states from limiting aviation rates, routes, and services.

The cost of an air-ambulance bill is split into two main parts, according to a study completed by the Montana legislature. First, a liftoff fee, which ranges from $8,500 to $15,200 in Montana, and then a per-mile charge for the flight, which ranges from $26 to $133 a mile.

Some air ambulance companies offer membership programs as protection from big bills. For an annual fee of about $60 to $100, patients face no cost beyond what their health insurance pays if they use that company’s services.

But Laslovich said that doesn’t always work, because a patient can’t always know who is going to pick them up.

There is a lack of understanding about the actual costs of running an air-ambulance business, said Rick Sherlock, the president of the Association of Air Medical Services. The costs include specialized labor, training, equipment, and fuel.

“So those cost drivers are there and [it’s necessary] to maintain readiness to respond 24 hours a day, seven days a week, 365 days a year,” Sherlock said.

He says some air-ambulance companies remain out of insurance networks because they can’t always reach in-network deals that allow them to stay profitable.

“I think what you also have to look at is that negotiations between [air ambulance] companies and insurance companies take place when there’s good negotiations on both sides,” Sherlock said. “In situations where there may be only one or two insurance options in an area, it’s harder and harder to negotiate on a level playing field.”