Definition
A legacy U.S. military data communications system used for the secure, store-and-forward transmission of digital messages between Department of Defense units and supporting agencies, including the relay of certain aeronautical information such as flight plans and weather data between military and civilian aviation systems.
Plain English
A military computer messaging network that was used to send written messages and flight information between military bases and air traffic facilities. It worked like a secure version of email, holding each message and then forwarding it to the right destination.
Context Anchor
Seen in FAA acronym and NOTAM contraction lists, especially in older or military-related message-handling references.
Derivation
From 'Automatic Digital Network.' 'Automatic' because messages were routed and forwarded by the system itself rather than by human operators, and 'Digital' because the messages were sent as computer data rather than voice. Knowing this helps you see it as an early version of automated military email.
Why Pilots Care
Pilots flying military or joint-use operations may see AUTODIN referenced in procedures or paperwork describing how flight plans and aeronautical messages reach the controlling agency. It is largely historical now, having been replaced by newer systems, but the term still appears in older publications.
Intuition Check
Do not read the “AUTO” part as autopilot or automatic flight control. AUTODIN refers to an automatic message network used by the Department of Defense.
Example Sentence 1
Before newer systems took over, a military flight plan filed at the base operations desk was often passed to air traffic control through AUTODIN.
Example Sentence 2
Older mission orders sometimes arrived via AUTODIN before digital systems were updated.