Say this about the airline business: it's unpredictable.

For example, you can't be sure your plane will leave or arrive on time. You're always nervous your luggage won't be waiting for you. The degree of difficulty getting through heightened security varies from place to place. All that and more about flying are unpredictable.

Which is why under ordinary circumstances, this week's news that American Airlines is leaving Stewart Airport wouldn't come as a huge surprise. Except what's happening at Stewart these days isn't ordinary.

By most accounts, passenger traffic is up. The parking lots are filled. The terminal is a beehive of activity, particularly compared to the sleepy days when American was the first company to set up shop at Stewart. Meanwhile, construction on a highly anticipated feeder road from Route 84 to the airport is progressing. Moreover, the Port Authority of New York and New Jersey is about to take control of Stewart's operations, likely meaning plenty of spillover from an already overcrowded LaGuardia, JFK and Newark.

So in the face of all that, American Airlines (actually, the auxiliary American Eagle brand) is booking its last flights in and out of Stewart for Labor Day weekend.

What gives? American says it can't make money at Stewart. That's surprising, since my own frequent experiences with the airline is that its flights to and from Chicago often are near-capacity. But, OK, we believe American if it says Stewart doesn't work for its bottom line; after all, why would it close if it made money?

Having said that, given the prospects for Stewart, wouldn't it make sense to hang on a bit longer?

Something just doesn't add up.