Definition
A communications system used by air traffic control facilities to exchange flight data electronically between facilities, replacing or supplementing voice coordination for handing off and tracking aircraft as they move from one ATC facility's airspace to another's.
Plain English
A behind-the-scenes computer link that lets one ATC facility send flight information to another ATC facility automatically, instead of controllers having to call each other on the phone for every handoff.
Context Anchor
Seen in FAA acronym lists and in references to air traffic control support systems, not usually as a cockpit procedure a pilot operates directly.
Derivation
Inter- means 'between,' and facility refers to an ATC facility (such as a tower, TRACON, or center). So 'interfacility data system' literally means a data link between ATC facilities.
Why Pilots Care
Smooth interfacility data exchange is what makes seamless handoffs possible. When it works, your flight plan and target follow you cleanly from one controller to the next; when it fails, expect delays, repeated readbacks, or temporary loss of radar identification.
Example Sentence 1
Flight plan data was passed from the center to the approach facility through IFDS before the handoff.
Example Sentence 2
IFDS ensures that route amendments are coordinated across multiple facilities.