Butte is an old mining town, tucked away in the southwest corner of Montana with a population of about 34,000. Locals enjoy many things you can’t find elsewhere — campgrounds a quick drive from downtown and gorgeous mountain ranges nearby. But in Butte, as in much of rural America, advanced medical care is absent.

People in Butte who experience serious trauma or need specialty care rely on air ambulance flights to get them the help they need.

There were close to 3,000 air ambulance flights in Montana in 2014, and Amy Thomson was on one of them, curled up among the medical bags in the back of the fixed-wing plane. Her 2-month-old daughter, Isla, had a failing heart, and the hospital that could help her was 600 miles away.

“They did such wonderful care of her, and they tried to take great care of me, but in that moment I couldn’t let go,” Thomson says. “I was so afraid that if I closed my eyes that would be my last vision of her.”

Thomson watched as Isla was placed in a small box strapped to a gurney inside the air ambulance.

Seattle Children’s Hospital saved Isla’s life. Her family’s health insurance took care of the costs beyond her deductible — except for that critical air ambulance ride to Seattle.

The Thomsons read their insurance plan, and interpreted it to mean that any emergency medical transportation was covered.

Isla Thomson with her older sister. Isla turned 2 years old in November. Courtesy of the Thomson family hide caption

toggle caption Courtesy of the Thomson family

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

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

When a patient needs an air ambulance, the first priority is getting them needed care as fast as possible. Patients don’t always know who is going to pick them up or if the ambulance is an in-network provider.

That can make a huge difference — and lead to huge bills.

“Of all the complaints we have received in our office, not one person was uninsured,” says Jesse Laslovich, 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, plus 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 who use that company’s services face no cost beyond what their health insurance pays.

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

“You want to know what my personal opinion is about what the problem is?” Laslovich asks. “It’s money.”

There is a lack of understanding about the actual costs of running an air ambulance business, says 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 says.

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 says. “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.”

There are only three health insurance companies operating in Montana, and at least 14 air ambulance providers. At the time of Isla’s trip to Seattle Children’s Hospital, the Thomsons’ insurer, PacificSource, had no in-network agreements with any air ambulance company in the family’s area. (PacificSource didn’t return calls seeking comment.)

For people who think they are protected from crippling health care bills because they have insurance, the cost of an ambulance ride can be a shock.

A Montana interim legislative committee is now investigating the wide range of pricing by air ambulance companies within the state. The state of Maryland has taken on a similar investigation.

In North Dakota an air ambulance company is suing the state for adding regulations on the industry.

Amy Thomson ended up not having to pay for her flight, but only after repeated appeals. According to Thomson, on the same day they were arranging a time to meet with a lawyer, she was notified by her insurance company that it would pay an additional amount of about $30,000, as well as the $13,000 out-of-network fee to the air ambulance company. The air ambulance firm waived the rest of its fee.

Isla turned 2 in November. She’s a healthy child with big blue eyes, but at times her mom still worries.

“Nobody takes a life flight for a joy ride,” she says. “You’re not going on Kayak.com and booking a life flight.”

Thomson didn’t think the flight should be free, but says the huge bill felt wrong. “I ethically believe this is a part of health care,” she says. “This is not some separate entity. There is something ethically wrong that these companies are profiteering off of people’s worst moments in their lives.”

This story is part of NPR’s reporting partnership with Montana Public Radio and Kaiser Health News.