On Thursday, April 5, 2018 at 7:29:48 PM UTC-5, wrote:
IIRC, back more than a few years ago when we had no tracking systems or cell phones We had a fairly new pilot trying for a gold distance flight out of Turf, while the rest of us were flying a racing task of around 200 miles.. After landing everyone back except the newbie. we tied down and started the debriefing. Looking around we saw his wife sitting in the car waiting on him. It was very close to dark and we were getting worried, so the decision was made and straws drawn as to who was going to call flight service and report our missing pilot. The side of the conversation I heard went something like this. "Hi this Alan ------, Im calling to report a missing glider and pilot, what say again, yes yes thats the pilot, good, he is safe at Indian Hills, we will send his crew. Thank you very much" Turns out that as soon as he landed he switched to 121.5 and called a airliner passing overhead and they relayed back to Flight service his name and N number and location so that when we called to report him missing they had the info. Something I have never had to do, but ingenious just the same

That's exactly what we were taught to do years ago (basically before cellphone era), and we actually did take advantage of airliner pilots in relaying our messages after outlanding when necessary. Many of them were/are glider pilots themselves, after all.