ARINC SPECIFICATION 635-4-2003 PDF

Full title and description

ARINC Specification 635-4:2003 — HF Data Link Protocols. This ARINC specification provides protocol definitions and design guidance for exchanging bit-oriented data over an air‑ground High Frequency Data Link (HFDL) in an OSI/ATN environment, intended for use by airborne equipment and associated ground systems.

Abstract

Defines the functions and protocols required for airborne components of the High Frequency Data Link (HFDL) system to transfer messages between HF ground stations and aircraft avionics when data are encoded in a bit‑oriented format. The specification maps air/ground services and protocols to OSI layers and aligns the HFDL protocols with Aeronautical Telecommunications Network (ATN) concepts to support interoperability and message exchange across HF air/ground links.

General information

• Status: Published (2003). Some technical catalogs/databases list the document as later superseded by ARINC 633‑2 (2012) — see Notes/FAQ.
• Publication date: December 2003 (commonly cited as 22 December 2003 / 2003‑12).
• Publisher: ARINC (Aeronautical Radio, Incorporated).
• ICS / categories: Aviation / on‑board equipment and instruments (example ICS listing: 49.090 in some catalogs).
• Edition / version: Issued as part 635‑4 (2003). Some records list an edition identifier (catalogues vary).
• Number of pages: 124 pages (typical page count reported by standards distributors).

Scope

The specification covers design guidance and the set of services, protocols and procedures required to exchange bit‑oriented data between aircraft and HF ground stations. It describes air/ground interfaces and protocol behavior across OSI layers for HFDL operation, including functional requirements for airborne components, message composition, error handling and interoperability within the ATN context. The document is intended for use where HFDL is employed as an aeronautical data link for operational and aeronautical messaging.

Key topics and requirements

• HFDL protocol definitions for air/ground data exchange and bit‑oriented framing.
• OSI layering and service definitions to ensure compatibility with ATN concepts.
• Airborne component functional requirements (message composition, priorities, ARQ and error management).
• Physical‑ and data‑link layer air/ground interface specifications and radio frequency management for HF.
• Interoperability and subnetwork considerations for connecting aircraft systems to HFDL ground networks.

Typical use and users

Primary users include avionics systems engineers, aircraft communications equipment manufacturers, airlines and flight operations engineers, HF ground station operators, system integrators, and certification/regulatory authorities involved in deploying and validating HFDL solutions. HFDL is used operationally to exchange operational control messages, some ATN/CPDLC traffic and other aeronautical data where HF coverage is required.

Related standards

Companion and related ARINC characteristics/specifications referenced in catalogs and literature include ARINC 634 and ARINC 753 (HFDL system characteristics), and other ARINC series documents addressing avionics communications and interfaces. Some catalogs list ARINC 633‑2 (2012) as a later related/updated document that supersedes or replaces material from ARINC 635 parts in certain contexts. The specification also relates to ICAO/ATN concepts and general aeronautical communications practices for HF.

Keywords

ARINC 635‑4, HF Data Link, HFDL, air‑ground data link, ATN, OSI layers, airborne protocols, avionics communications, radio frequency management.

FAQ

Q: What is this standard?

A: ARINC 635‑4:2003 is an ARINC specification that defines High Frequency Data Link (HFDL) protocols and the functions required of airborne components to exchange bit‑oriented data with HF ground stations.

Q: What does it cover?

A: It covers air/ground interface protocols mapped to OSI layers, message composition and priorities, physical and data‑link layer services for HF links, radio frequency management, and interoperability requirements to support HFDL within the ATN framework.

Q: Who typically uses it?

A: Avionics manufacturers, airlines, communications equipment suppliers, HF ground station operators, system integrators and certification authorities use this specification when designing, deploying or certifying HFDL equipment and services.

Q: Is it current or superseded?

A: The original ARINC 635‑4 document was published in December 2003. Commercial standards catalogs differ on status: several distributors list the 2003 issue as the referenced publication, while other databases indicate the material was later superseded or consolidated under ARINC 633‑2 (2012) for subsequent revisions or replacement of related HFDL content. Users planning implementations or compliance work should verify the applicable, current ARINC document with ARINC (Aviation-Industry authorities) or their standards provider before relying on this 2003 text.

Q: Is it part of a series?

A: Yes — ARINC 635 is a multi‑part family covering HF Data Link topics (earlier and adjacent parts exist such as 635‑1/2/3/4 in historical records), and ARINC maintains many related communications characteristics and specifications. Check ARINC's catalog or standards distributors for the complete list and part relationships.

Q: What are the key keywords?

A: HF Data Link, HFDL, ARINC 635, air‑ground protocol, OSI, ATN, airborne protocol, avionics communications.