I met a guy on the trail this past weekend who apparently uses his iPhone on airplane mode to act as his GPS navigation while backpacking. He swore it was reliable but I am hesitant to put any sort of trust in Apple products. I was wondering if any of you use an iPhone like this. Does it work when there's no cell signal? I was just about to buy a Garmin Instinct Solar, but if this is reliable then I'll save the money I guess.