It was a long time ago, but I had a similar looking incident with an RAF Britannia. We had night stopped in Calgary and were climbing through ten thousand feet on the way to Gander when there was a loud bang as the co-pilots windscreen crazed in a similar fashion. We returned to Calgary as we were not sure of the security of the broken windscreen, which was replaced two days later. We were informed it was definitely a failure of the windscreen