OPPOSITE DIRECTION AIRCRAFT (P/CG) - Aircraft are operating in opposite directions when:
a.
They are following the same track in reciprocal directions; or

b.
Their tracks are parallel and the aircraft are flying in reciprocal directions; or

c. Their tracks intersect at an angle of more than 135°.
OPTION APPROACH - An approach requested and conducted by a pilot which will result in either a touch-and-go, missed approach, low approach, stop-and-go or full stop landing. (See Cleared for the option)
ORGANIZED TRACK SYSTEM - A moveable system of oceanic tracks that traverses the North Atlantic between Europe and North America the physical position of which is determined twice daily taking the best advantage of the winds aloft.
OUT - The conversation is ended and no response is expected.
OUTER AREA (associated with Class C airspace) (P/CG) - Nonregulatory airspace surrounding designated Class C airspace airports wherein ATC provides radar vectoring and sequencing on a full-time basis for all IFR and participating VFR aircraft. The service provided in the outer area is called Class C service which includes: IFR/IFR-standard IFR separation; IFR/VFR-traffic advisories and conflict resolution; and VFR/VFR-traffic advisories and, as appropriate, safety alerts. The normal radius will be 20 nautical miles with some variations based on site-specific requirements. The outer area extends outward from primary Class C airspace airport and extends from the lower limits of radar/radio coverage up to the ceiling of the approach control's delegated airspace excluding the Class C charted area and other airspace as appropriate.
OUTER COMPASS LOCATOR - (See Compass Locator)
OUTER FIX - A general term used within Air Traffic Control to describe fixes in the terminal area, other than the final approach fix. Aircraft are normally cleared to these fixes by an Air Route Traffic Control Center or an Approach Control Facility. Aircraft are normally cleared from these fixes to the final approach fix or final approach course.
OUTER MARKER/OM - A marker beacon at or near the glide slope intercept altitude of an Instrument Landing System approach. It is keyed to transmit two dashes per second on a 400 Hertz tone which is received aurally and visually by compatible airborne equipment. The Outer Marker is normally located four to seven miles from the runway threshold on the extended centerline of the runway. (See Marker Beacon, Instrument Landing System)
OVER - My transmission is ended; I expect a response.
OVERHEAD APPROACH/360 OVERHEAD - A series of predetermined maneuvers prescribed for Visual Flight Rules arrival of military aircraft (often in formation) for entry into the Visual Flight Rules traffic pattern and to proceed to a landing. The pattern usually specifies the following:
(1)
The radio contact required of the pilot.

(2)
The speed to be maintained.

(3)
An initial approach 3 to 5 miles in length.