Using Find my Friends and Airplane mode

I am playing around with Find my Friends for an event I have upcoming. To test its affectiveness, I have asked several friends to follow each other and see how accurate it is here in Osaka, Japan. My friend had a low battery and put his phone on airplane mode until he could get to a charger. Interestingly, it immediately showed that his location was "Location Unanavailable" - which I thought was only shown if they turned off the service, or if the phone had been out of range for more than two hours. I checked with him and he had not turned off the service and was still using wifi.

Does anyone know if turning on airplane mode results in a "Location Unanavailable" immediately, the same as if someone had chosen "Hide my location"? Or if it shows the previous location for two hours?