I read an AAIB report a couple of weeks ago where it took some time to find the injured pilot and his passenger (hip and leg injuries) and a recommendation was that had a mobile phone been immediately available and not in an unreachable bag on the back seat, then they could have phoned for assistance which would have arrived about a half hour earlier (the crash was near an unmanned farm strip).
I was also told that up to date 4G phones are terribly unlikely to interfere with any aircraft systems and don't need to be turned to aeroplane mode and the airlines only insist on it to avoid in flight punch ups.
I guess that is so judging by the noises I hear from hand baggage in flight where innumerable phones are getting a welcome text as they cross borders and that there are not easyJets raining down on us.