ARINC 841-1 PDF

The scope of this specification covers all the provisions necessary to enable communication of large messages between airborne and ground applications without degradation of the availability required of air-ground links to deliver Air Traffic Service (ATS) messaging in a timely manner.

This standard defines a communication protocol for air-ground communications aiming at:

• Exchanging AOC messages of any type between aircraft and ground to take place over ARINC 618 networks, without current networks limitation (e.g., 3360 bytes maximum size limitation for ACARS downlinks, 3520 bytes for ACARS uplinks)

• Allowing existing ARINC 620 AOC exchanges between ground and aircraft to occur over IP networks

The standard is intended to be used only for AOC exchanges, but its design should not preclude future use by Air Traffic Control (ATC).

The provisions defined in this document include specifications for:

• Communication services provided to the users

• Messages format and content

• Messages encoding and compression

• Protocols for exchanging messages over the different subnetworks

The standard provides guidelines and recommendations on the maximum message size that can be transmitted over the ACARS subnetworks, in order to preserve RF bandwidth and not degrade the overall ACARS availability.

Purpose of Document

The purpose of this document is to provide an industry standard for Media Independent Aircraft Messaging (MIAM) which permits the exchange of a large volume of data over Aircraft Communications Addressing and Reporting System (ACARS) subnetworks or broadband Internet Protocol (IP) subnetworks.

The volume of data transmitted over ACARS datalink is increasing, notably on new generation aircraft. Although availability of new IP-based communication systems provides additional communication paths, ACARS will continue to be used for Aeronautical Operational Control (AOC) message transmission.

There is thus a need for a protocol that allows avionic systems to exchange large volumes of data (larger than the maximum ACARS message) over ACARS subnetworks (VHF Digital Link Mode 2 (VDL2) or traditional ACARS subnetworks under certain conditions) as well as broadband IP subnetworks.

ARINC Specification 841 was developed to:

• Improve ACARS performance and efficient Radio Frequency (RF) spectrum utilization

• Define a communication service common to ACARS and IP subnetworks Provide ACARS access to new datalink users (e.g., Electronic Flight Bag (EFB) applications)

• Avoid proliferation of proprietary solutions