Aircraft Communications: ACARS vs. CPDLC
What is ACARS and how does it work?
ACARS stands for Aircraft Communications Addressing and Reporting System. It is a digital communication system that allows aircraft to send and receive short messages with ground stations via radio or satellite links.
ACARS is used for a variety of purposes, including sending and receiving flight plans, weather updates, maintenance messages, and other operational data. The system also allows for the monitoring of aircraft systems and performance, which can help identify potential issues before they become critical.
The ACARS system operates on a VHF frequency of 131.550 MHz, which is reserved for aeronautical use. Messages are sent using a protocol known as ARINC 618, which formats the data and transmits it between the aircraft and the ground station.
In modern aircraft, ACARS messages are sent and received through satellite links, which provide global coverage and allow for real-time communication between the aircraft and ground stations. This is particularly useful for long-haul flights, where the aircraft may be out of range of traditional VHF radio links for extended periods of time.
How is ACARS different than CPDLC?
CPDLC (Controller-Pilot Data Link Communications) and ACARS (Aircraft Communications Addressing and Reporting System) are both digital communication systems used in aviation, but they serve different purposes and operate in different ways.
CPDLC is a data link system that allows air traffic controllers and pilots to communicate directly via text messages, rather than using voice communication. CPDLC is primarily used for en-route communication, such as giving clearances, making route changes, and providing other instructions to the aircraft.
While ACARS messages are usually sent automatically and require little interaction from the pilots, CPDLC messages require active input from the pilots. Pilots must respond to each message from the controller by selecting pre-defined response options on their cockpit display.
Another key difference between CPDLC and ACARS is that CPDLC uses a different protocol (ATN/IPS) and operates on a different frequency (136.975 MHz) than ACARS. CPDLC messages are also typically sent and received through satellite links, which provide global coverage and allow for real-time communication between the aircraft and air traffic control.
Overall, both CPDLC and ACARS are important tools for aircraft communications.
