Flight Mode Icon
The CEA (Consumer Electronics Association) has created a standard icon for the industry to indicate when a device is in "flight mode".
See: Flight Mode
If manufacturers use the standard icon, it makes it easier for flight attendants to verify that devices are in flight mode. This increases the chances that airlines will allow phones to be used during flight (in flight mode.) It is also possible that some airlines may only allow devices with the standard icon to be used during flight, although no airline has adopted such a policy as of 2016.
As of early 2016, manufacturers have been slow to adopt the standard icon, using a variety of non-standard icons instead.
CEA guidelines state that the icon should be accompanied by the words "transmitter disabled" when possible. There is also a standard icon for when the phone is not in flight mode, which should be accompanied by the words "transmitter enabled".