What is CPDLC - AirSatOne

What is CPDLC - AirSatOne

What CPDLC is not?


Lets start off first with what CPDLC is not. At AirSatOne and at some recent aviation meetings we have heard people refer to CPDLC as logging on to the network and activating or downloading a flight plan. We have even heard the FAA refer to this activity as being CPDLC. This is definately not CPDLC. CPDLC is when the flight crew is communicating with a live person at ATC for the purpose of coordination of aircraft activities.  

What does CPDLC stand for?


CPDLC stands for Controller / Pilot Datalink Communications. It is a digital way of sending text messages for communication between ATC and the Pilot instead of voice communications.

Please explain CPDLC in more detail?


CPDLC is typically used as part of the FANS 1/A flight environment. FANS 1/A consists of both ADS-C and CPDLC. ADS-C is the automated position information portion where CPDLC is communications between the Pilot and the Controller. CPDLC has been historically been used outside the radar controlled environment and used in the FANS 1/A controlled airspace. Due to radio congestion, misinterpretation and missed voice communications CPDLC is gaining popularity in the radar control environment where VHF voice communications has traditionally taken place. CPDLC can be used by itself, without ADS-C, and can be transmitted via VHF of SatCom with relatively low latency - basically the message gets where it need to go right away with practically un-noticeable delay.

CPDLC text messages are entered on the flight crews CDU (control display unit) keypad. Messages are constructed by pressing logical keys that construct the message using canned text. The flight crew should not have to hand spell the text messages – they should only have to enter a few characters or numbers on occasion.

Once the message is sent the flight crew will get an acknowledgment that the message was received. If the message was sent while using CPDLC in the FANS 1/A environment there are requirements for how long the message response takes from both ATC to Pilot and Pilot to ATC. These response times take into account the time the digital message takes to make its trip and the time that a human being would need to respond – the total round trip is taken into consideration to determine the separation needed to conduct safe flight.  


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