navigational changeover point

changeover point (COP)

The point at which an aircraft navigating on an ATS (air traffic service) route segment, defined by reference to very high frequency omnidirectional radio-ranges, is expected to transfer its primary navigational reference from the facility behind the aircraft to the next facility ahead of the aircraft (ICAO). At this point, the pilot should change the receiver's frequency from the station behind to that of the station ahead. Changeover points are established to provide an optimum balance in the signal strength and quality between facilities at all levels to be used and to ensure a common source of azimuth guidance for all aircraft operating along the same portion of a route segment. COPs are prescribed for jet routes, area navigational routes and airways, or other direct routes for which a minimum en route altitude is designated. The COP is located midway between the navigational facilities for the route segments or at the intersection of radials or courses forming a dogleg, in the case of dogleg route segments. When not located at the midway point, aeronautical charts depict the COP location and give mileage to the radio aids. Also called a navigational changeover point.