All Nippon Airways’ announcement shows how far carriers are going to differentiate themselves. (Kimimasa Mayama/Bloomberg)

By Julie Johnsson | Starting Monday, All Nippon Airways plans to begin introducing women-only bathrooms across the wide-body fleet that it uses on international routes.

The concept is appealing to many travelers. For women, it means guaranteed to access to a cleaner lavatory, where the toilet seat will always be left down.

But male travelers polled by ANA, which is Japan’s second-largest airline, liked the idea as well, said ANA spokesman Justin Massey.

“[I]t was determined in general that the females preferred not following a male into restrooms and that males, to some extent, mentioned not feeling totally comfortable with a female coming into the restroom after they’ve used it,” he added.

For now, ANA doesn’t plan to outfit its new women’s restrooms with special toiletries, although it is exploring that concept, Massey added. And ANA won’t create any male-only toilets.

But ANA’s announcement Tuesday is another reminder of the creative lengths that carriers are going to differentiate themselves in an environment where competition for passengers is tough and pricing comparable across the airline industry.

Bathrooms, usually memorable for the wrong reasons on planes, are proving fertile ground for carriers with the deep-pockets to introduce new services, or the imagination to find new ways to appeal to passengers.

First-class travelers on Emirates Airline’s A380 super-jumbo jets can take in-flight showers. ANA is installing bidets in its first- and business-class bathrooms on long-range planes. Ryanair, at the other extreme of the luxury spectrum, is toying with the concept of coin-operated lavatories.

ANA’s plan to designate one lavatory per plane for women is a smart marketing tactic, analysts said. The airline’s wide-body jets hold many bathrooms, so men won’t be inconvenienced. And it gives ANA an unusual way to appeal to women, who studies have shown handle travel arrangements in a majority of households.

“As a strictly marketing piece, it’s a very clever idea,” said Tim Kern, aviation writer and consultant based in Anderson, Ind.

The Japanese carrier, which flies non-stop from Chicago’s O’Hare International Airport to Tokyo and is a close partner to United Airlines, said that the women-only lavatory will be designated by pink signage.  It will be off-limits to male passengers unless there are few women on board – or unless a traveler experiences a medical emergency.

But there’s one potential downside to ANA’s concept: long potty lines, especially as women primp for arrival at their destination.

“They still have the option of going to the one-size fits all [lavatory], so they can’t be worse off,” Kern said. “Men will be better off. Women will stand in line for the women’s lavatory and not so much for the men’s. That means men can get in and out [quickly] — and leave the seat anyway they want.”