I just Googled "autopilot flight" and got loads of hits that might help you. I then Googled "waypoint flight accuracy" and got a few hits that might be useful to you. As far as "flight technical error" is concerned, this is the error provision that is made in instrument procedure designs to account for pilot error and/or pilot delay in initiating a climb, descent or turn.
You can find out more about it from Volume 1 of ICAO document 8168 - Pans Ops.
HTH