Coded Departure Routes

AIM ¶ 4-4-5 — Coded Departure Routes

AIM 4-4-5 explains Coded Departure Routes (CDRs): the 8-character ATC reroute system for weather and congestion. Study guide for pilot students.

In Plain English

A Coded Departure Route (CDR) is a pre-coordinated reroute that ATC can issue quickly when your filed route is blocked by weather or congestion. Instead of reading a long amended clearance, the controller simply gives you an eight-character code, and you load the matching route.

The code structure is:

Characters 1–3: departure airport identifier
Characters 4–6: arrival airport identifier
Characters 7–8: a suffix assigned by the overlying ARTCC

For example, PITORDN1 is an alternate route from Pittsburgh to Chicago. Key operational points:

CDRs are updated every 56 days (the standard charting cycle), so pilots must verify their CDR data is current.
Historically, only air carriers with a Memorandum of Agreement participated.
General aviation pilots can now opt in by entering "CDR Capable" in the remarks section of the flight plan, telling ATC they can decode a CDR and are willing to accept the alternate routing.

This is a recommended/voluntary program — not a regulatory requirement — but it can dramatically reduce delays when the NAS is constrained.

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AIM Source Text

FAA 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.

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Oral Exam Questions a DPE Might Ask

Q1What is a Coded Departure Route and when does ATC use one?

Per AIM 4-4-5, a CDR is a pre-coordinated reroute, identified by an eight-character designator, that ATC uses to rapidly reroute departing aircraft when the filed route is constrained by weather or congestion.

Q2How is a CDR designator structured? Give an example.

Per AIM 4-4-5, a CDR is eight alphanumeric characters: the first three identify the departure airport, characters four through six identify the arrival airport, and the last two are chosen by the overlying ARTCC. Example: PITORDN1 is an alternate route from Pittsburgh to Chicago.

Q3How can a general aviation pilot participate in the CDR program, and how often must CDR data be updated?

Per AIM 4-4-5, a GA pilot participates by entering "CDR Capable" in the remarks section of the flight plan, indicating the ability to decode a CDR into a route and the willingness to fly a different route than filed. CDRs are updated on the 56-day charting cycle, and aircrews must ensure their CDR is current.

Related Paragraphs in Chapter 4

¶ 4-4-1

ATC Clearance

¶ 4-4-10

Adherence to ATC Clearance

¶ 4-4-11

IFR Separation Standards

¶ 4-4-12

ATC Speed Adjustments

¶ 4-4-13

Runway Separation

¶ 4-4-14