Travelers were rocked by thousands of flight delays over the Memorial Day holiday weekend, partly due to post-pandemic staffing shortages.

Southwest Airlines Pilots Association President Casey Murray told "Fox & Friends First" Tuesday there are numerous "inefficiencies" that are causing travel delays, combined with severe weather across the country.

Southwest Airlines

(iStock)

"There were so many workers in the U.S. that sort of disappeared from the entire labor force. There's a pilot shortage. It's difficult to recruit and retain the best pilots. And so we're kind of fighting that as well," he told host Carley Shimkus.

The kickoff to the summer travel season saw cancellations piling up over the weekend. More than 5,000 flights were canceled globally from Friday to Monday, according to flight-tracking website FlightAware.

DELTA AIR LINES TO CUT 100 DAILY FLIGHTS OVER THE SUMMER

Delta Air Lines, which had already issued a warning that it was trimming its summer schedule, suffered the most among U.S. airlines, with more than 250 flights, or 9% of its operations, eliminated on Saturday. 

"Before noon Sunday, FlightAware.com reported more than three-dozen flights delayed and about a dozen canceled at Sea-Tac. Nationally, the website reported more than 350 flights had already been canceled on Sunday alone."

CLICK HERE FOR THE FOX NEWS APP

Murray said that airlines are still trying to replace pilots and other workers who haven't returned since the COVID pandemic began.

"I think it's going to be a challenge for everyone across the industry. Shortages from the ramp workers to operations agents, those who check you in, checking bags as well as to the pilots. It’s going to be a challenge and it's got to be managed by management," he said.

Murray said travelers should "hang in there" and predicted the issues will improve in the coming months.