The same thing happened to me about 2 years ago. We took off from Anchorage and two minutes later another FedEx MD-11 took off, with both of us going over to Japan. About 3 hours later, they flew right over the top of us. We moved out to the side and I took some great photos of them. I called them on 123.45 and got their employee numbers, and when I got home I had some prints made and enlarged and sent them to that crew. I don't remember, but I think I even got some "thank yous" from them. I just spent an hour looking for those images on my computer to no avail. They were great shots. Oh well.