(NewsNation) — This Thursday, hundreds of pilots for Delta Air Lines have planned protests in several states, seeking better pay and improved schedules.

In a statement Monday, the Air Line Pilots Association wrote that nearly 14,000 of their members are working longer hours even as the airlines cancel thousands of flights, angering customers. 

“When delays or cancellations happen, the pilots share in our passengers’ frustration,” Jason Ambrosi, a union official and Delta pilot, said in the statement. “As long-term stakeholders in our airline, seeing our operational reliability suffer is bad business and puts the Delta brand at risk.

“The perfect storm is occurring, Ambrosi added. “Demand is back and pilots are flying record amounts of overtime but are still seeing our customers being stranded and their holiday plans ruined.”

Greg Chin, communications director at Miami-Dade Aviation Department, is predicting the busiest Fourth of July weekend ever.

“We’re having a record-setting year,” Chin said. “We’ll see 125,000 to 150,000 passengers per day and that’s 20,000 passengers more per day than we saw last year.”

In other words, Airlines will be packed: AAA expects 3.5 million people will travel by plane this Fourth of July weekend.

“The bad news is our systems aren’t prepared to handle that many travelers right now,” says Scott Keys, a travel expert and founder of travel website, Scott’s Cheap Flights.

“If even a couple percentage points of pilots call in sick, then the domino effect begins. The best airlines have seen what was coming — seen that they were overextended and trimmed their schedules months ago,” he continued.

Travel experts say some of the airlines now plagued with those last-minute flight cancellations are the major players: Delta and American Airlines.

American just announced it is upping pay bonuses for some regional pilots as an incentive during the critical summer travel season.