# What is ACARS? ## Introduction ACARS stands for Aircraft Communications Addressing and Reporting System. It is a digital data link system for the transmission of short messages between aircraft and ground stations via radio or satellite. ACARS is used for a variety of purposes, including sending and receiving messages to and from the aircraft, such as weather reports, flight plans, and maintenance data. ACARS messages are typically short, and are transmitted in a format that is easy to read and understand. The messages are sent in a standardized format, which allows them to be easily decoded and displayed on a computer or other device. ACARS messages are transmitted over a variety of frequencies, including VHF, HF, and satellite frequencies. The messages are typically transmitted in bursts, and are received by ground stations or other aircraft that are equipped with ACARS receivers. ## Why ACARS is a bad term for this system ACARS is a bit of a confusing term because it refers to a specific protocol, but is often used to refer to the entire system of aircraft communications. Typically, when you hear someone talking about ACARS, they are referring to the system of text messaging between aircraft and ground stations, rather than the specific protocol that is used to transmit those messages. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://book.acarsguide.com/acarsbook/intro/what-is-acars.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.