Fellow US Airways passengers got some rare help in passing the time when a Portland-based barbershop quartet entertained them with a song this month.

The members of Port City Sound, sitting together on the plane, eased into a rendition of “Under the Boardwalk,” while other passengers craned their necks to see the source of the mellow tones.

Other passengers pulled out their smartphones and recorded the impromptu session, and one resulting video that has been making the rounds on YouTube  had more than 3 million views by Thursday.

Jim Simpson, 70, of Hallowell, one member of the group, said in an email that the group was on its way to New Orleans for a competition. A flight attendant asked them to sing while the plane, loaded with passengers, was delayed.

A story about the episode in the Christian Science Monitor quotes Simpson: “That gig was totally unplanned, but it was a lot of fun. We’re certainly never shy about singing for people so when the stewardess asked us, well, we were happy to oblige.”

The Port City Sound Facebook page lists its members as Simpson, a bass; Fred Moore, tenor; Walt Dowling, lead; and Jim Curtis, baritone.