Inform an aircraft when it is observed in a position and on a track which will obviously cause the aircraft to
deviate from its protected airspace area. If necessary, help the aircraft to return to the assigned protected
1. RNAV ATS routes have a width of 8 miles and laterally protected airspace of 4 miles on each side of the route
2. Navigation system performance requirements for operations on RNAV ATS routes require the aircraft system be
capable of remaining within 2 miles of the route centerline. Aircraft approaching this limit may be experiencing a
navigation system error or failure.