Definition
Switched data service (SDS) is a digital communication service that establishes a temporary, on-demand data connection between two points, routing information through a network only for the duration of the exchange. In aviation, it refers to data link services used to pass operational information such as weather, clearances, or flight data between ground systems and aircraft or between facilities.
Plain English
A way of sending digital information between two points only when needed, with the connection opened just for that exchange and then closed again — similar to how a phone call connects you only while you’re talking.
Context Anchor
Seen in FAA acronym lists and technical communication-system references, more often in background or system documentation than in normal cockpit conversation.
Derivation
‘Switched’ comes from telecommunications, where a network ‘switches’ a connection into place on demand rather than keeping it permanently open. ‘Data service’ simply means a service that carries digital information rather than voice. Together, the term signals that the link exists only when there is data to send.
Why Pilots Care
Pilots increasingly rely on data link services for clearances, weather, and traffic information. Knowing that some of these services are switched (on-demand) rather than continuously connected helps explain occasional delays or the need to request a service before information arrives.
Intuition Check
Do not read “switched” as a physical switch in the cockpit being flipped on or off. Here it means the data connection is routed through a network when needed.
Example Sentence 1
The avionics suite uses a switched data service to pull updated weather only when the pilot requests it.
Example Sentence 2
Pilots may receive certain NOTAM updates via SDS when operating in areas with digital data link coverage.