When small towns rely on one employer, everyone is just a closed factory away from collapse.

That’s a reality many in Pennsylvania can understand — and have experienced. We know what it’s like when the only hospital shuts down, and you have to drive an hour to reach the emergency room. We know what happens when the only supermarket goes away, and suddenly all your meals come from a dollar store.

A lack of backup plans is the start of a domino effect. It isn’t long before other things start to leave too.

Arnold Palmer Regional Airport is learning that lesson now.

The departure of Spirit Airlines last month didn’t just eliminate the airport’s only commercial carrier. It also led to the loss of Transportation Security Administration staffing.

So what’s next?

Airport officials and charter operators say charter service could be the next domino to fall. Without TSA staffing, charter flights to destinations such as Atlantic City and Reno may have to relocate to other airports.

That might sound like a small thing compared to losing commercial air service. It isn’t.

Charters can be the next line of defense for a small facility, but it needs the support of a primary operation. Think about it like the snack bar at a movie theater. If there’s no movie to see, nobody’s going there to buy a $20 bucket of popcorn.

Airports have little sidelines like this. Rental cars. Gas for private planes. All of them become less relevant when the airport is no longer functioning as a viable transportation hub.

It’s a bad time to be finishing up a $22 million terminal expansion project, and people are seeing that.

The charter flights won’t stop flying. They will find a new location to fly from. If that has to happen, they won’t just come back like birds returning after winter should Arnold Palmer Regional Airport find a new single carrier to pin hopes on.

“They need to make it work; otherwise, you will have a $20 million banquet center next door,” said Antonia Battaglia-Elo, co-owner of Aliquippa-based

Preferred Casino Tours LLC.

Diversification is healthy for lots of reasons. It’s what your financial adviser will counsel rather than putting everything into a single stock. It’s best for your garden, protecting plants from disease and pests. A good business has multiple revenue streams rather than relying on a single product that might become obsolete overnight.

Arnold Palmer Regional Airport was a one-factory town, and the inevitable occurred.

What is happening now is the logical consequence.

Preserving charter service is part of the solution. Recruiting a new commercial carrier is part of the solution. Finding new ways to make the airport an asset to the region is part of the solution.

The solution isn’t finding a new Spirit. It’s having a vision for an airport diverse enough to survive — and doing the hard and ongoing work to make that happen.