Definition
An Automatic Call Distributor is a telephone system that receives incoming calls and routes each one to the next available specialist in a defined group, based on rules such as call type, time of day, or operator workload. In the FAA system, ACDs are used at Flight Service Stations to distribute pilot calls (for weather briefings, flight plan filing, and similar services) across available briefers.
Plain English
It is the phone system that automatically sends your call to the next free briefer when you call Flight Service, instead of you having to choose someone yourself.
Context Anchor
Pilots may see this abbreviation in FAA acronym lists or encounter the system indirectly when calling an aviation support facility, such as flight service or another phone-based help point.
Why Pilots Care
When you call for a briefing, you may be connected to any briefer in the network rather than a local one. Knowing this explains why you should always state your location and aircraft details up front — the briefer who answers may be hundreds of miles away and has no local context until you give it.
Intuition Check
Do not read “distributor” here as an engine part. In this context, it means a phone-call routing system.
Example Sentence 1
When the pilot dialed Flight Service, the ACD routed her call to the next available briefer rather than a specific person.
Example Sentence 2
During busy periods the ACD holds lower-priority calls until an agent becomes free.