Aircraft separation over the Atlantic
Was just wondering what methods are used to keep aircraft separate over large bodies of water such as the Atlantic, and indeed what the legal limits are for separation.
I was flying to Boston from the UK last year and glancing out of my window saw another aircraft at the same altitude at some distance. As I watched we got closer and closer together until it felt like we were more or less flying side by side. I had a real sense of the speed we were travelling by watching the contrails fly off the back of the other plane, and could almost make out the livery on the aircraft, despite the bright sunlight. With the very real sense of speed it felt as though a fairly minor change of direction by either aircraft could spell rapid disaster...
I came very close to alerting a member of cabin crew, as it seemed we were just destined to get ever closer! Does this sound unusual? Considering the levels of traffic accross the Atlantic is there a risk involved? I would assume that there are proximity alarms, and that one of the planes would notice the other before it was too late, but on this occasion it felt incredibly close!