The person who told me this story has never believed in Ghosts or Guardian Angels so what he told took me quite some time to grasp.
This person was a Flight Engineer in the Canadian Military, sort of like the on board Mechanic/Navigator, and had been in the Military his whole life. On this particular flight his mind was occupied and in turmoil, he wanted a drink even thought he had not drank in some time as he considered himself to have a problem with the bottle. The base they were flying to was extremely remote in Canada's far north with only a few buildings and a narrow runway strip, however they had a very nice Mess hall for Aircrews and it was common for the Captains to debrief their crews in these mess halls.
After landing this Flight Engineer had made up his mind and decided to have a drink or two during the debrief even though he almost lost his family in the past because of drinking. During the Debrief before he had ordered his drink a Captain had sat down beside him and told him that he was a friend of Bill - a code used in AA for identification. The Flight Engineer was relieved as he really needed someone to talk to about this and hopefully give him some support. Upon ending the conversation this Captain gave his name and contact details and told him to go to his Aircraft and find his book to read a certain step regarding relapse.
The flight engineer had done this and his craving for the drink was lifted and upon returning to the Mess hall low and behold the Good Captain was gone. As you can probably guess the administrative staff of several bases and establishments were given the mystery Captains details and they were non-existent.
Everyone in this mess hall had seen the Ghostly Captain but nobody had ever seen him before which was odd for an isolated locality as such. I can only guess it would have been a Guardian Angel or a Ghost sent to help a good man in need before he made a terrible mistake.