Delta, United Airlines, American Airlines, and Singapore Airlines have confirmed that the screens in their premium economy seats have cameras.

Now, passengers have concerns about privacy due to the cameras, which have been seen in seat-back entertainment systems on some international routes. The news that United and Delta also have screens with camera lenses arrives after passengers spotted cameras on Singapore and American.

United and Delta told Buzzfeed News that the cameras were an included feature by Panasonic, the company that manufactured the entertainment systems, and that the cameras are inactive, the outlet reports. A spokesperson for United told Buzzfeed that cameras are “a standard feature that manufacturers of the system have included for possible future purposes such as video conferencing” and the airline has “no plans to use them in the future.”

The video conferencing feature isn’t available on United but is being used on some Emirates flights with Panasonic entertainment systems, in first class.

In a statement to Buzzfeed, Delta said the cameras “are not functional” and the airline “does not have any plans to install the necessary software to use them.”

American told the outlet last week that the cameras could have possible future use, “such as hand gestures to control in-flight entertainment,” but “have never been activated, and American is not considering using them.”

Though airlines maintain that the lenses aren’t spying on passengers, stickers or covers would ease customers’ minds, who worry that seat-back cameras could be hacked or used to surveil them.

A customer on a Singapore Airlines flight shared a photo of the seat-back display on Twitter last week, writing, “Just found this interesting sensor looking at me from the seat back on board of Singapore Airlines. Any expert opinion of whether this a camera? Perhaps @SingaporeAir could clarify how it is used?”