Online, reactions to the video were divided: You’re either a recliner or you’re not.
But proper airplane etiquette is more complicated than that, Henry Harteveldt, a travel industry analyst, said. Seat reclining follows an unwritten rule: You don’t do it unless you really need to.
“Airplane etiquette is you only recline when necessary, and if you must recline, just put the seat back a little bit to get the comfort you need without encroaching too much on the person behind you,” he said.
Still, Mr. Harteveldt said, the passenger behind Ms. Williams was wrong to keep striking her seat.
“The person in the seat has the right to recline, that’s the way it is,” he said. “It may not be fair, but life itself is not fair.”
Mr. Harteveldt, citing increasingly claustrophobic cabins, added that “emotions run higher and hotter on airplanes” as they are more crowded and “legroom and personal space has been reduced.”
In 2018, the Federal Aviation Administration declined to regulate the size of seats on airplanes, despite consumer complaints about comfort and questions about safety.
In an interview with CNBC on Friday, Ed Bastian, the chief executive for Delta Air Lines, appeared to agree with the unwritten rule of the skies. “The proper thing to do is, if you’re going to recline into somebody, you ask if it’s OK first,” he said.
Michael Boyd, an aviation analyst, said on Friday that “in any case, it is the airline that determines the amount of space a seat takes up, not the passengers themselves.”