I am surprised there are so many negative comments about ATC-mandate SLOP in Chinese airspace. I actually have been a fan of it and use SLOP on a routine basis in airspace where I am permitted to do so.
I believe one reason why ATC enforces it is because of the increased complexity of Chinese RVSM. We fly metric levels however this needs to be converted to feet altitude levels for most aircraft (according to the tables) and then flown in feet to guarantee 1000' separation between aircraft. Therein lies the hazard-- one crew applying the wrong conversion.
With GPS navigation giving lateral accuracy within a few meters compared to previous navigation systems, "randomness" has decreased. I like SLOP because instead of exactly 1000 feet (or slightly less) separation between somebody's fin and my belly, I am now looking at several 1000 feet of separation (lateral x vertical). In the case of China, we can be talking about more than 4 miles of separation between opposite direction traffic in the enroute structure and 2000 feet separation between same-direction traffic. In general, I really like that!
Last edited by Panama Jack; 2nd Sep 2011 at 08:46.