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Understanding FANS: ADS-C & CPDLC

November 2012
Understanding FANS

A lot has changed in the world of air traffic control during the past 70 years. To help diagram some of the more recent changes, I have created and released a four-part video series on Understanding Future Air Navigation Systems (FANS), the avionics system that provides direct data link communication between the pilot and air traffic controller. Below are the highlights of the first video: ADS-C & CPDLC.

What is FANS

The acronym FANS stands for "Future Air Navigation System." It is designed to increase the communication between the pilot and controllers by providing a common language that is not influenced or interrupted by language barriers or accents. FANS can be divided into two parts, Automatic Dependent Surveillance Contract (ADS-C) and Controller Pilot Data Link Communication (CPDLC).


With ADS-C, there are three types of contracts that can be set up by your controller and one set up by the pilot.

Periodic contracts are time-based and can be varied when necessary by Air Traffic Control ATC needs.

An Event contract is a contract set up by the ATC that predesignates your aircraft’s altitude, vertical speed or any of several other different parameters. If you deviate from any of these parameters, they are notified immediately.

Demand contracts: ATC initiates this contract when they want to know where everybody is right now. Everyone responds on demand.

Mayday Message: This contract is controlled and initiated by the pilot during emergency circumstances.  


CPDLC is a standardized, formatted language that is used in text messages sent between ATC and the cockpit of the aircraft.

To view the entire four-part FANS video series can be accessed and viewed at http://www.duncanaviation.aero/videos/understanding-fans.


Justin Vena Avionics Installations Sales Rep Astra, Challenger, Embraer, Global, Gulfstream, Westwind Battle Creek, MI (BTL) +1 269.968.8789

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