Does it cause any safety issues if I don't put my phone on flight mode in an airplane?

[Kera]

Every smartphone has the flight mode or airplane mode as in some phones. It is expected to activate airplane mode or flight mode when you are on board a moving airplane. Does it cause any safety issues to the moving plane if a passenger fails to activate airplane mode on board a flight?

 

[magnus2022]

Airplane mode is necessary in flight because phone frequencies may be interference with airplane signals.
Airplane mode is solely designed to turn your phone to incommunicado at any time without switching your phone off.

 

[Kross]

Airplane mode doesn't allow any interference from phone signals to the cabin crew trying to communicate with the control tower.

 

[eLdavis]

While it might not actually cause a plane crash it might interfere with their communication system, especially during takeoff and landing.