Delta's new Boeing 777 features broadest seats of any wide-body U.S. airliner

Only Frontier offers wider economy seats than Delta.

Delta announced on Monday its "full-fleet interior renovation" of 777s that will increase the width of economy seats to 18.5 inches, the broadest of any dual-aisle aircraft and wider than those offered by competitors American Airlines and United.

Frontier Airlines is the only carrier with wider seats in economy class, some of which are 19.1 inches across.

As part of Delta's redesign, the main cabin will feature nine seats abreast instead of 10. Each passenger also will have a personal power outlet and an entertainment system featuring a 11-inch screen.

A newly modified 777-200ER flying from Detroit to Beijing and was the first of the Boeing series to feature Delta’s latest cabin upgrades, which will be made on all eight 777-200ER jets and all 10 777-200LR by the end of 2019.

Delta didn't confirm an exact cost for the upgrades but said "it's part of a multi-billion-dollar project."

Flyers Rights Advocacy Group President Paul Hudson said he's unsure if offering flyers more room is a trend that will continue.

"It's hard to determine if this is a real improvement, as it's apparently only for super-long-haul flights," Hudson said. "Some airlines are shrinking space between rows and claiming more leg room by eliminating seat padding and recline."