Originally Posted by
peuce
Okay Rob, I take your point.
So, some pilots already do it now in enroute ... ATC surveillance tolerances aren't good enough to see it ... what's the problem? Continue doing it. No rule required.
There are some routes that require exact tolerances, some are due to the proximity to military airspace. In one case I had observed a domestic jet tracking 0.2nm right of track. The pilot confirmed this and I had to instruct them to regain track to remain clear of military controlled airspace, with resulting coordination to the military unit for boundary traffic. And this was on a one way route.
Some ATC routes/boundaries require exact tracking for coordination purposes and even the smallest offset can make a difference. Pilots will be largely unaware of which routes this applies to. Tracking offset, without approval from ATC can result in additional workload and in some case, technical breakdowns of separation.