You may use your FreeStyle Libre 3 system while on an aircraft, following any requests from the flight crew. You will not receive alarms or glucose readings while your phone is in airplane mode unless you enable Bluetooth1.
Some airport full-body scanners include x-ray or millimeter radio-wave, which you cannot expose your system to. The effect of these scanners has not been evaluated and the exposure may damage the system or cause inaccurate results. To avoid removing your system, notify the Security Officer prior to proceeding through the airport security checkpoint and you may request another type of screening. If you do choose to go through a full-body scanner, you must remove your sensor1.
FreeStyle Libre 3 sensors can be exposed to common electrostatic (ESD) and electromagnetic interference (EMI), including airport metal detectors1.
1 FreeStyle Libre 3 User's Manual.