DELAYS or cancellations because of bad weather or mechanical problems are exasperating but common occurrences in air travel, but increasingly, passengers aren’t making it to their destinations for yet another reason: not enough pilots. The gate agent may not tell you that’s why you’re grounded, but a dearth of qualified pilots is disrupting, reducing and even eliminating flights.

“After 35 years analyzing and following this industry, I’ve never seen anything like it — and it’s only going to get worse,” said Dan Akins, an aviation economist and consultant who conducts quarterly surveys of both pilots and airlines to identify staffing trends. “Everyone knows the house is on fire and no one can find the hose.”

In addition to widespread delays and cancellations, at least 29 communities, from Modesto, Calif., to Macon, Ga., have lost air service since 2013, and hundreds more had their number of flights reduced. Meanwhile, airports that haven’t lost service complain they can’t get additional flights to keep up with local economic development. “We’ve had $5 billion of new industry come to our area, and the airlines say they can’t grow us because there aren’t enough pilots,” said Mike Hainsey, executive director of the Golden Triangle Regional Airport, which serves Columbus, Starkville and West Point, Miss.

So what’s causing the shortage? To start, there are just a lot more passengers. According to the Department of Transportation, airlines carried a record 895.5 million passengers in the United States in 2015, up 5 percent from the previous year. To meet global growth over the next 18 years, Boeing forecasts that the industry will need more than a half million new pilots.