Unless specified in the separation standard, an aircraft’s use of these procedures does not affect the application of prescribed separation standards. Note 1.- SLOP are approved procedures that allow aircraft to fly on a parallel track to the right of the centre line relative to the direction of flight to mitigate the lateral overlap probability due to increased navigation accuracy and wake turbulence encounters. Strategic Lateral Offset Procedures (SLOP) Flying a little right of course can save you when you or someone else makes a mistake. Of course those were not oceanic midair collisions, but they serve to illustrate the point. More about those: EMBR-135BJ N600XL and Gol 1907, and DHL 611 and Bashkirskie Avialinii 2937.

The altitude error is precisely what happened to the victims of Gol 1907, DHL 611, and Bashkirskie Avialinii 2937. If someone programs the wrong course or levels off at the wrong altitude, they may be precisely on the wrong course, in position to hit someone who is properly and precisely on course. It is almost all good because there is a chance a navigation or altitude error can end very badly. These days, the skies are packed with airplanes but GPS allows us to navigate within a tenth or so of course centerline. But there were not a lot of airplanes flying oceanic and the accuracy wasn't all that important. In the days before INS, being within 10 miles was a major accomplishment. In the days before GPS, we would be lucky if our oceanic position was within a couple of miles of where we should have been.

Atc code 7700