Answer Description
The best option is to instruct the user how to disable mobile data for the duration of the trip. While this is disabled they cannot access the internet using their cellular connection but could still use WiFi, Bluetooth, etc. This is supported by all major smart phone operating systems. Mobile data may also be referred to as cellular data.
Wikipedia
Airplane mode, aeroplane mode, flight mode, offline mode, or standalone mode is a setting available on smartphones and other portable devices When activated, this mode suspends the device's radio-frequency (RF) signal transmission technologies (ie, Bluetooth, telephony and Wi-Fi), effectively disabling all voice, text and phone services GPS may or may not be disabled, because it does not involve transmitting radio waves The mode is so named because most airlines prohibit the use of equipment that transmit RF signals while in flight Typically it is not possible to make phone calls or send messages in airplane mode, but some smartphones allow calls to emergency services
Airplane_mode - Wikipedia, the free encyclopedia