Definition
Aircraft are operating in opposite directions when they are flying on courses 180 degrees apart, or when their courses are within 45 degrees of being directly opposed, and their flight paths are projected to cross or pass close enough to each other that ATC must apply separation procedures.
Plain English
Two aircraft are heading toward each other, or nearly toward each other, on paths that will meet or come very close. Air traffic control treats them as opposite direction traffic so they can be safely separated.
Context Anchor
You may hear this term in ATC traffic calls, runway operations, route planning, or discussions about aircraft separation.
Why Pilots Care
Confirms the runway or approach path is clear before takeoff or landing, directly preventing head-on collisions.
Intuition Check
Do not assume opposite direction means only two aircraft flying directly at each other on the exact same line. In this FAA use, it can also include parallel opposite paths or crossing paths that meet at a wide opposing angle.
Example Sentence 1
Tower advised the Cessna of opposite direction aircraft on a five-mile final and asked if the pilot could accept a short delay for departure.
Example Sentence 2
Before taking the active runway at the non-towered airport, the pilot scanned for any opposite direction aircraft on short final.