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Countries around the world are implementing a new way for pilots and Air Traffic Control (ATC) to communicate. Called Controller Pilot Data Link Communications (CPDLC), the technology aims to supplement traditional radio traffic with text-based messages.

CPDLC is a key component of the Future Air Navigation System (FANS), a new way of communicating within avionics. The goal of both is the same - more efficient air traffic communication and surveillance, meaning improved aviation safety and reduced errors often found in voice communications.

"CPDLC is probably the most confusing term in aviation today. It simply stands for Controller Pilot Data Link Communication. The best way to think about it is as a verb and not a noun, like texting on the phone." Jake Biggs, Textron Aviation Manager, Aftermarket Sales Engineering

CPDLC and FANS mandates vary across the world and continue to change. Europe already mandates the use of Protected Mode CPDLC for operators flying above 28,500 feet. That version of CPDLC uses a message set called Aeronautical Telecommunications Network Build 1 (ATNB1). All United States and North Atlantic flights use a message set called FANS-1/A+, but it's only mandated on North Atlantic flights. While there is no requirement currently in the United States, the Federal Aviation Administration (FAA) says it "has implemented an extensive phased plan to implement CPDLC capabilities across the entire domestic U.S. airspace."

CPDLC allows both pilots and ATC to send a pre-determined set of messages to one another, similar to text messaging. These can include clearances, information, or requests. The goal is increased efficiency and understanding and decreased misinterpretation.

"When flying a plane, we have three fundamental things to do - aviate, navigate and communicate. When communication is accurate from both the pilot and the controller, everything works well. CPDLC can and certainly does assist both parties in the communication process." Mark Vanderpool, Textron Aviation Flight Operations Manager

CPDLC advantages

• Reduced communication time between controllers and flight crews
• Fewer errors from manually updating routes
• More clear communication

Communicates important information to and from ATC.

"Automation that is clearly understood and communicated accurately, does help alleviate common mistakes or miscommunication between the pilot and controller," said Mark Vanderpool, Textron Aviation Flight Operations Manager.

Service professionals suggest scheduling your CPDLC upgrade in advance to take advantage of prime scheduling flexibility and supply pricing. Contact Textron Aviation service experts to plan your transition.

How does CPDLC work?

The messages can be either single element (EX: CLIMB TO [level]) or multi-element (EX: CLIMB TO [level], CLIMB AT [vertical rate] MINIMUM). It is recommended to use abbreviations and codes if doing so will shorten the message. Similarly, pleasantries and filler words should be avoided.

"There is no significant learning curve. However there needs to be an understanding of basics, and the type of communication. Good accurate communication relies on this foundation." Mark Vanderpool, Textron Aviation Flight Operations Manager

It is up to a pilot and controller's discretion whether they prefer to use voice or CPDLC.

CPDLC equipped aircraft can receive digital departure clearances faster than voice coordinated clearances. The airport must be one of the participating airports, but this can be a big fuel and time savings. Eventually, enroute services will reduce crew workload and minimize human error.

What equipment do I need?

Depending on your current avionics, the exact solution will vary. The good news is you may have some necessary elements already on board your aircraft.

To start, CPDLC will require an appropriate avionics suite. Different suites provide different levels of CPDLC support. For instance, the GARMIN G5000 avionics suite has CPDLC as an optional install. The GARMIN G3000 can onboard a CPDLC solution, but technically, it has more limited data communication compared to the full capability.

However, just having the suite isn't enough. You'll need to update your avionics suite to enable the CPDLC functionality to use the system.

"Textron Aviation has worked with industry groups and regulators to make sure our designs meet the exacting requirements associated with CPDLC." Jake Biggs, Textron Aviation Manager, Aftermarket Sales Engineering

One other thing you'll need on your aircraft is a VDL Mode 2 VHR Radio and/or an iridium data transceiver. The VDL Mode 2 VHF is used over land and the iridium data transceiver is utilized in remote and oceanic airspace.

These requirements are a general rule of thumb, but it's best to consult with your OEM to understand the exact solution for your aircraft.

"Depending on the vintage of the aircraft, the upgrade can be as simple as updating software, or as complex as adding a Communication Management Unit or Function (CMU/F), software, and data link radios. The process is greatly simplified if the customer asks for CPDLC for a specific environment, such as Domestic US airspace, North Atlantic, or Europe," said Jake Biggs, Textron Aviation Manager of Aftermarket Sales Engineering.

What equipment do I need?

Appropriate avionics suite

Avionics updates to enable CPDLC

Mode 2 VHF Radio and/or iridium data transceiver

Where is CPDLC required?

As of February 2020, CPDLC is mandated in Europe for aircraft flying (with a Certification of Airworthiness after February 7, 2020) above 28,500 ft. However, there are some exemptions to the rule outlined in ANNEX I and ANNEX II from the Official Journal of the European Union (FWI - KING AIR turboprops have a permanent exemption).

The Federal Aviation Administration (FAA) says it is not currently required in Title 14 of the Code of Federal Regulations (14 CFR) to have data link communications when operating in the National Airspace System (NAS).

What does the FAA require to operate CPDLC?

For data link communication operations in the United States, the FAA requires non-commercial (Part 91) operators to be proficient with the procedures and operations associated with the data link system in accordance with their flight manuals. They must also meet minimum equipage requirements if they are using CPDLC in United States airspace.

Domestic Part 91 operators do not need a Letter of Authorization (LOA) to operate within United States airspace, but they should note, flying over oceanic and remote continents does require an A056 LOA, as outlined by the FAA.

Depending on the part of the flight and the location, the FAA requires different equipment and functionality, as outlined in the FAA chart below.

Where is CPDLC available in the United States?

For a far more detailed understanding of CPDLC, operating procedures, message examples, flight crew procedures, controller procedures and more, download the Global Operational Data Link Document (GOLD) from the International Civil Aviation Organization and the corresponding annexes.