Airline teletype system

The airline teletype system uses teleprinters, which are electro-mechanical typewriters that can communicate typed messages from point to point through simple electric communications channels, often just pairs of wires. The most modern form of these devices are fully electronic and use a screen, instead of a printer.

Historical development

The airline industry has been using teletype technology since the early 1920s using radios stations located at 10 airfields in the United States. The US Post Office and other US government agencies used these radio stations for transmitting telegraph messages. It was during this period that the first federal teletype system was introduced in the United States to allow weather and flight information to be exchanged between air traffic facilities.

In 1929, Aeronautical Radio Incorporated (ARINC) was formed to manage radio frequencies and licence allocation in the United States, as well as to support the radio stations that were used by the emerging airlines, a role ARINC still fulfils today. ARINC is a private company owned by many of the world's airlines including; American Airlines, Continental Airlines, British Airways, Air France,and SAS. Other non-airline companies also own a share of ARINC including the Ford Motor Company.

In 1949, the Société Internationale de Télécommunication Aeronautique (SITA) was formed as a cooperative by 11 airlines: Air France, KLM, Sabena, Swissair, TWA, British European Airways, British Overseas Airways Corporation, British South American Airways, Swedish A. G. Aerotransport, Danish Det Danske Luftfartselskab A/S, and Norwegian Det Norske Luftfartselskap. Their aim was to enable airlines to be able to use the existing communications facilities in the most efficient manner.

Morse code was the general means of relaying information between air communications stations prior to World War II. Generally, it was only necessary to relay a message between one or two stations. After World War II, there was an increase in the number of commercial aircraft operating, and these aircraft were capable of flying greater distances than in the past. As a result, the Aeronautical Fixed Telecommunications Network (AFTN) was implemented worldwide as a means of relaying the air traffic communications, sometimes through the use of radioteletype.

Today, the airline industry continues to use teletype messages over ARINC, SITA or AFTN networks as a medium for communicating via messages. Most teletype messages are machine-generated by automatic processes. IATA standardise teletype message formats throughout the airline industry.

An example of a TTY message (IATA TypeB format)

QD AAAABBB. - IATA message to AAAABBB (priority=deferred) XXXXYYY 111301 - from (origin code + timestamp) ASM - IATA type (keyword). Identifies type of message UTC - Time mode (Coordinated Universal Time). UTC or LOCAL 27SEP03899E001/TSTF DL Y - Message Reference line NEW - ASM subtype (Action Identifier) BA667/13APRJ 319 C1M25VVA4C26 - Flight and date of flight; fleet & equipment information LHR1340 BCN1610 - Station/time for depart & arrival LHRQQQ 99/1 - Route information. 99 is the passenger departure terminal code QQQBCN 98/A - Route information. 98 is the passenger arrival terminal code QQQQQQ 906/PAYDIV B - Route information. LHRQQQ 999/1 - Route information. 999 is the aircraft arrival terminal code QQQBCN 998/A - Route information. 998 is the aircraft departure terminal code SI - Other supplementary information (free text)

IATA Teletype messages mostly have a 7 character address whereas an AFTN Teletype message always has an 8-character address.

ee also

*ACARS