What are FANS 1/A & CPDLC?
Developed by the International Civil Aviation Organization (ICAO), Boeing, Airbus, Honeywell, and others, Future Air Navigation System (FANS) is a protocol for safely managing the expected increases in the volume of air traffic in the coming years. FANS 1 was developed by Boeing and later adopted by Airbus (FANS A). FANS 1/A uses an early version of both systems and has been used for 15 years by the airlines and contains two parts.
Controller Pilot Data Link Communication (CPDLC) allows two-way, digital communication between a controller and a pilot when an aircraft is out of range of traditional analog very high frequency (VHF) or high frequency (HF) voice-radio communications. As with terrestrial-based messaging between cell phones, the air traffic controllers and the flight crews communicate via text messages. The CPDLC application has three primary functions:
- Facilitates the exchange of messages between the pilot and the ATC who is currently in control of the aircraft.
- Clarifies dialogue between ATC and the aircraft crew who speak different languages (removes the accent from the picture because all communication is text-based).
- Allows the crew to review ATC instructions.
- Automatic Dependent Surveillance-Contract (ADS-C)
ADS-C is both a standard and an application that automatically sends reports from an aircraft to an air traffic services unit (ATSU) and requires no action from the pilot. The report includes data, such as the aircraft identification and address, air vector, ground vector, projected profile, meteorological data, min/max ETA and Extended Projected Profile (EPP) data. When operating in normal mode, the system generates three types of reports:
- Periodic—The ATC can set or alter the update rate as needed (a higher update rate is usually required in high traffic areas).
- Event—A change in vertical rate, lateral deviation or altitude automatically triggers a report.
- Demand—An ATC can request an update as needed, and this does not affect an existing contact preset rate.
There is a fourth type of contract; unlike the previous three, it is initiated and cancelled by the pilot, not the controller. This Emergency Contract is automatically triggered by a MAYDAY message.
- CPDLC—facilitates communication between an ATC and a flight crew.
ATN-BI—(PM CPDLC, Link 2000+ and Datacomm) is the ICAO engineering designation for this technology standard. It refers to just text messaging. It’s a data link service that allows text-based communication between an ATC and the flight crew but doesn’t include a surveillance component. Equipment using this standard is intended for use in areas where ground surveillance already exists.
Protected Mode CPDLC is Honeywell’s term for the same technology standard. In Europe, Link 2000+ (EASA’s term for the technology) is the Eurocontrol Program that coordinates the implementation of operational CPDLC. Datacomm is the FAA’s term for the technology. Although Link 2000+ is similar to the FANS/CPDLC system used in North Atlantic Airspace, Link 2000+ uses VDL Mode 2 datalink and Aeronoautical Telecommunications Network (ATN) instead of Aircraft Communications Addressing and Reporting System (ACARS) and is meant to be used in areas where ground surveillance already exists. There is no surveillance component to this technology.
There are currently more than 1,000 FANS 1/A-equipped commercial, business and military aircraft operating around the world.
Datalink services are available in most of the world’s oceanic routes and in some domestic airspace, as well. The services provide invaluable support at transfer points where aircraft enter domestic airspace or exit domestic airspace and enter oceanic. The enhanced communication abilities aid the ATC on both sides of tracks and particularly when a controller at one center hands off an aircraft to another ATC center because with a FANS-equipped aircraft, the handoff occurs seamlessly behind the scenes.
Along the routes that have not yet been mandated for FANS, the flight crew has to call an ATC and give verbal updates as to their whereabouts with no support from ground surveillance. This lack of accurate position data is a problem because if an ATC doesn’t know exactly where an aircraft is, the ATC has to maintain greater distance between aircraft. With FANS, an ATC can track aircraft along the entire route and safely and efficiently track and accommodate more aircraft in the airspace. The majority of these enhanced services are available to FANS-1/A-equipped aircraft. Ground facilities around the world are upgrading to FANS work stations.
Which datalink service a particular operator selects depends entirely on what equipment is available for the type of aircraft.
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