The company published a study that said an 18-inch wide seat improves the quality of sleep by 53 percent over a seat that is 17 inches wide.
"When it comes to flying long haul in economy, an inch makes a huge difference on passenger comfort," said Irshaad Ebrahim, speaking for the London Sleep Center, which conducted the study.
Victoria Day, a spokeswoman for Airlines for America, a domestic trade group, said it should be up to airlines to determine the width of their seats, the Los Angeles Times reported Sunday.
"We believe individual airlines should be able to determine fleet configurations that best meet their customers' needs, as they do today," Day said.
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