@Chris I can clearly see you will be one of the folks I would like to meet after I read the story about your Grandfather Jack. My father Capt Makonnen was third batch from Ethiopian Airforce. I recently met Jim Hansen and his father James Hansen was chief pilot at one point and flew into Addis, the very first Ethiopian Airlines B720B and presented it to the Emperor himself in 1962.
My grandfather was General Manager of Ethiopian Airlines in 1962 and flew that B720B into Addis. I believe James Hensen was his First Officer, but I will need to get his logbooks and can verify that in a few weeks. I have sent you a Private Message, please check over there.