Airliners line up for take off at Los Angeles International Airport in Los Angeles, California.

For the millions who are flying somewhere this summer, they may want to pack some extra patience.

The industry trade group Airlines for America is expecting a record 236.1 million people to take a flight between June 1 and Aug. 31, an increase of 3.7 percent from last summer.

"As the economy grows along with household net worth, passengers are taking advantage of persistently low airfares for their summer travel plans," said John Heimlich, vice president and chief economist at Airlines for America.