NEW YORK – Boeing engineers think they have a solution for smelly, grimy airplane bathrooms: ultraviolet light.

The aircraft manufacturer has filed a patent for a self-cleaning lavatory that disinfects all surfaces in just three seconds.

Many passengers would welcome more sanitary bathrooms, but they may have to wait a while to benefit from Boeing’s technology.

The typical domestic plane has just three bathrooms – one in first class and two at the rear. That number hasn’t changed in decades even as airlines cram more rows onto planes and fill an ever-higher percentage of those seats. And with less time on the ground, those bathrooms aren’t always cleaned to the fullest, despite the increased use.

Boeing’s new bathroom design uses ultraviolet light to clean the bathroom between uses. The Chicago-based company says the system will take three seconds to clean the toilet seat, sink and countertop in an unoccupied lavatory. Boeing plans to use Far UV, which it says is different from the waves used in tanning beds and is not harmful to people.

The design incorporates a hands-free faucet, soap dispenser, trash flap, toilet lid and seat and a hand dryer to decrease the number of surfaces passengers touch. Boeing said it is also working on a hands-free door latch.