FYI, "Airplane mode" has traditionally been a mode where all transmitting radios are turned off.
Since GPS works simply by receiving signals from the GPS satellites and doing math (so no outgoing trasmission from the phone is required), it is not usually turned off in "airplane mode".
However, iOS devices prior to v8.2 did turn off GPS in airplane mode. I have no idea why.
In the future, "airplane mode" may become more relaxed, where it only turns off the voice/data cell radio transmitter, but leaves Bluetooth and/or WiFi enabled.