Definition
An unstaffed VHF radio transceiver, located away from a Flight Service Station (FSS), that lets pilots talk to an FSS specialist by radio from areas the FSS's main antennas cannot reach. The pilot transmits on the published RCO frequency, and the signal is relayed by landline or other link back to the parent FSS, where a briefer responds.
Plain English
A remote radio site that extends a Flight Service Station's reach. You call on the RCO frequency from the cockpit, and a briefer at the FSS hears you and answers, even though the FSS itself may be hundreds of miles away.
Context Anchor
Seen in Flight Service Station discussions, on charts, and in the Chart Supplement when a pilot needs a frequency to contact Flight Service for weather, flight-plan, or other enroute information.
Derivation
"Remote" means situated away from the main facility; "outlet" here means an access point — a place where the FSS's communication service is made available. Together: an access point for FSS communication located away from the FSS itself.
Why Pilots Care
They allow pilots to obtain weather briefings, file flight plans, and receive assistance without being in direct radio range of the primary station.
Intuition Check
An RCO is not an electrical outlet and it is not a staffed station. It is a remote radio access point that connects your aircraft radio to Flight Service.
Example Sentence 1
Unable to reach Flight Service directly, the pilot tuned the RCO frequency shown on the sectional and opened her IFR flight plan from the cockpit.
Example Sentence 2
In remote regions without a nearby Flight Service Station, RCOs provide the only reliable way to reach specialists for en route assistance.