Type B Messaging

Overview

Type B messaging is the store-and-forward communications system that has carried structured, text-based operational data across the aviation industry since the era of physical teletype machines in the early-to-mid 20th century. Although the original electro-mechanical teletypes disappeared decades ago, the message formats, addressing scheme, and switching concepts they established are still in daily use, delivered today over IP-based infrastructure operated primarily by SITA and ARINC (part of Collins Aerospace).

How It Works

Type B is fundamentally a transport and addressing layer rather than a single message type. It defines:

What Travels Over It

A wide range of standardized operational message types are transmitted over Type B networks, including passenger and load messages, disruption and irregular-operations notices, and many other structured formats defined by IATA and used between airlines, airports, ground handlers, and reservation systems. These individual message types are distinct standards in their own right; Type B is the underlying network and formatting convention that carries them, not the content itself.

Current Status

Type B remains widely used across the industry decades after its origin because so many airline, airport, and ground-handling systems were built around it, and because it offers guaranteed, low-cost, asynchronous delivery. At the same time, the industry has been steadily moving toward XML- and JSON-based alternatives — such as AIDX — that carry richer, more structured data and integrate more naturally with modern web services. Providers now typically deliver Type B messaging over IP networks rather than legacy teletype circuits, and gateway services exist to bridge Type B traffic with newer XML-based systems, so the two paradigms coexist rather than one having fully replaced the other.

Key Characteristics