AIM 4-4-5

CDRs provide air traffic control a rapid means to reroute departing aircraft when the filed route is constrained by either weather or congestion.

CDRs consist of an eight-character designator that represents a route of flight. The first three alphanumeric characters represent the departure airport, characters four through six represent the arrival airport, and the last two characters are chosen by the overlying ARTCC. For example, PITORDN1 is an alternate route from Pittsburgh to Chicago. Participating aircrews may then be re-cleared by air traffic control via the CDR abbreviated clearance, PITORDN1.

CDRs are updated on the 56 day charting cycle. Participating aircrews must ensure that their CDR is current.

Traditionally, CDRs have been used by air transport companies that have signed a Memorandum of Agreement with the local air traffic control facility. General aviation customers who wish to participate in the program may now enter “CDR Capable” in the remarks section of their flight plan.

When “CDR Capable” is entered into the remarks section of the flight plan the general aviation customer communicates to ATC the ability to decode the current CDR into a flight plan route and the willingness to fly a different route than that which was filed.