Commercial airliners typically utilize upwards of 27 antennas. While we think of antennas as devices used primarily for voice comms, there are other systems that use them for controlling steering, trim, flaps, etc., the “fly-by-wire” method instead of mechanical cables, to control the attitude (up, down, left, right) of an aircraft.(Ex; If a pilot wants to turn right the “stick” or “wheel” is pulled or turned to the right. That action activates a transmitter that sends an RF signal to a servo motor or motors to change the configuration of the respective movable surfaces on the wings and vertical stabilizers. my guess is the use of fly-by-wire saves in weight, eliminating the need for most cabling and wires. While these wireless systems are built to stringent standards that protect them from unwanted RF interference, any system that emits RF needs to be vetted as per FAA and FCC regulations. And there’s the rub… there are thousands of devices that would need to be tested individually, not just on one airliner, but on each individual airliner, even if they were of the same type of aircraft! An impossible endeavor. And the regulations stipulate that “receive only” devices such as scanners also be included because they too emit RF. Not in the sense of the transmitted power of a two-way radio, but the minute splurious emissions given off by electronic devices which include scanner receivers. Some airlines will leave the decision up to the pilots as to wether a device is acceptable or not but most pilots come down on the side of caution-they are not electronic engineers and don’t want to be held responsible for allowing something that is mostly unknown to them. I have not flown since the TSA came to be but prior to their existence, the restriction policy was largely ignored. I’ve never been asked to turn on my scanners or portable Ham walkie-talkies that I hand carried aboard an aircraft but I always packed my carry-on bags with the devices on top, for easy access should that need arise. There’s also restrictive regulations if traveling abroad… some country’s don’t allow some of these devices. That could mean they may be confiscated without the ability to snail mail them back to your home residence if checked when trying to get through customs! It’s a possibility I would avoid by leaving your comms gear at home. Check before you fly!
)
