Definition
That portion of airspace between the U.S. 12 nautical mile limit and the Oceanic Control Area/Flight Information Region (CTA/FIR) boundary, within which air traffic control is provided. Offshore/Control Airspace Areas may be classified as either Class A airspace or Class E airspace to provide air traffic control services to aircraft operating beyond domestic airspace.
Plain English
A block of airspace just off the U.S. coast, beyond the 12-mile territorial limit but before international oceanic airspace begins. ATC still controls traffic in this zone, even though it sits over the ocean rather than over land.
Context Anchor
Seen in FAA airspace descriptions, charted offshore routes, and discussions of controlled airspace near coastal or oceanic operations.
Derivation
"Offshore" simply means away from the shore, over water. The term is paired with "Control Airspace" to make clear that, although the airspace is over open water and outside the 12-mile territorial boundary, it is still controlled airspace where ATC services are provided.
Why Pilots Care
Tells the pilot whether ATC services are available or whether VFR procedures and self-separation apply over water.
Grounding Statement
Picture a marked box of sky extending out over the ocean, with published sides and altitudes, where ATC service is still available.
Intuition Check
Do not read “offshore” as meaning “uncontrolled because it is over water.” In this term, it means an airspace area away from land where control services may still apply.
Example Sentence 1
After departing the Louisiana coast, the helicopter remained in an Offshore/Control Airspace Area classified as Class E while en route to the oil platform.
Example Sentence 2
While operating IFR through the Offshore/Control Airspace Area, the crew received radar vectors from the center.