American Airlines is shaving off an additional two inches of economy class legroom on some of the seats in its new Boeing Co. 737 MAX jets, just as relations between U.S. airlines and their passengers sink to a new low.

The new planes will have more seats than earlier versions of the jet, shrinking the distance between seat backs, or pitch, to 29 inches (74 cm) from the current distance of 31 inches (79 cm), on three rows of seats, a spokesman for the carrier said.

The space between the remaining rows will drop to 30 inches from 31 inches. American said it expects the new planes in the fall and that they will go into service later this year.

"These (seats) are designed to be used in a very space-efficient way," American spokesman Joshua Freed said. "Even though the pitch comes in at 29 (inches), the seats are built to maximize knee space and seat space."

The move to cram more passengers onto planes is likely to antagonize customers, already upset by costlier amenities and aging infrastructure.

At a congressional hearing on Tuesday, airline executives - including a representative for American - received scathing criticism about their customer service, after the furor surrounding a passenger being dragged from a full United Airlines plane to make room for airline employees.

"Some don't charge fees. Some do charge fees. Some charge fees for baggage. Some charge fees for oxygen. Who knows?" Representative Mike Capuano said at the tense hearing.