Mr. Bartlett gave a number of potential uses for the cameras, including seat-to-seat or seat-to-ground video chats, motion-activated control of movies, games and other options displayed on the screen and smart lighting that dims when the camera detects that the passenger is sleeping. Airlines, he said, could also create digitally branded frames so passengers could take selfies and share them on social media.

The entertainment system manufacturers are embedding the cameras across all their product lines, which means, according to Joe Leader, chief executive officer of the Airline Passenger Experience Association, that airlines had no choice but to install them. And though the cameras have been on airliners for several years, most passengers did not seem to notice them.

Of the reaction to Mr. Kamluk’s tweet, Dr. Leader said, “When people are surprised, it hits a nerve,” especially if they see a camera where they do not expect one.

Emirates, based in Dubai, has found a use for the camera installed on a portable tablet in its first-class suite. Using an app called Room Service, a passenger can talk to flight attendants.

“We use it to allow the passenger to ask the crew for something, and they have a crew screen and camera in the galley,” said Patrick Brannelly, vice president for passenger experience at Emirates. The passenger has to enable the camera to be seen by the crew, but the passenger cannot see the crew in the galley, he said. “Emirates would never allow the camera to be on without making it 100 percent clear to the passenger that it was on.”