I was recently on a flight from Gatwick UK to Santorini. I enjoy flying and like to sit by a window, i often marvel at seeing other aicraft fly above and below in various directions, it puts the real speed into perspective. I am aware that aircraft must fly within their given 'corridor' for obvious reasons however i was quite shocked whilst gazing out on my Santorini flight when, like a flash, i saw a British Airway aircraft zip past us in the opposite direction so close i could clearly see the markings and the windows let alone the fact that it was virtually at the same level as us, was this a 'near miss', i would like to know the legal minimum 'separation' distance that aircraft must adhere to as deemed by the CAA.
I believe that the vertical separation is just 1000 feet, which can look pretty close but is quite safe. Distance on the same altitude is several miles