Aeronautical Terms beginning with O
OAT
Outside Air Temperature
Objectivity
The singleness of scoring of a test; it does not reflect the biases of the person grading the test.
OBS
Omni-bearing Selector
Obscuration
Denotes sky hidden by surface-based. obscuring phenomena and vertical visibility restricted overhead.
Obscuring phenomena
Any hydrometeor or lithometeor other than clouds; may be surface based or aloft.
Obstacle
An existing object, object of natural growth, or terrain at a fixed geographical location or which may be expected at a fixed location within a prescribed area with reference to which vertical clearance is or must be provided during flight operation.
Obstacle Clearance Surface (OCS)
An inclined or level surface associated with a defined area for obstruction evaluation.
Obstacle departure procedures (ODP)
A preplanned instrument flight rule (IFR) departure procedure printed for pilot use in textual or graphic form to provide obstruction clearance via the least onerous route from the terminal area to the appropriate en route structure. ODPs are recommended for obstruction clearance and may be flown without ATC clearance unless an alternate departure procedure (SID or radar vector) has been specifically assigned by ATC.
Obstacle Free Zone
The OFZ is a three dimensional volume of airspace which protects for the transition of aircraft to and from the runway. The OFZ clearing standard precludes taxiing and parked airplanes and object penetrations, except for frangible NAVAID locations that are fixed by function. Additionally, vehicles, equipment, and personnel may be authorized by air traffic control to enter the area using the provisions of FAAO JO 7110.65, Para 3-1-5, VEHICLES/EQUIPMENT/PERSONNEL ON RUNWAYS. The runway OFZ and when applicable, the inner-approach OFZ, and the inner-transitional OFZ, comprise the OFZ.
Obstacle Identification Surface (OIS)
The design of a departure procedure is based on TERPS, a living document that is updated frequently. Departure design criteria assumes an initial climb of 200 feet per NM after crossing the departure end of the runway (DER) at a height of at least 35 feet above the ground. Assuming a 200 feet per NM climb, the departure is structured to provide at least 48 feet per NM of clearance above objects that do not penetrate the obstacle slope. The slope, known as the obstacle identification slope (OIS), is based on a 40 to 1 ratio, which is the equivalent of a 152-foot per NM slope.
Obstruction
Any object/obstacle exceeding the obstruction standards specified by 14 CFR Part 77, Subpart C.
Obstruction lights
Lights that can be found both on and off an airport to identify obstructions.
Occluded front
A frontal occlusion occurs when a fast-moving cold front catches up with a slow moving warm front. The difference in temperature within each frontal system is a major factor in determining whether a cold or warm front occlusion occurs.
Occluded Front
The front formed by a cold front overtaking a warm front and lifting the warm air above the Earth’s surface. An occlusion (or frontal occlusion) forms when an air mass is trapped between two colder air masses and is forced to higher and higher levels.
Occlusion
Same as occluded front—a composite of two fronts as a cold front overtakes a warm front or quasi-stationary front. (commonly called occlusion or frontal occlusion).
OCS
Obstacle Clearance Surface
Octane
The rating system of aviation gasoline with regard to its anti-detonating qualities.
ODALS
Omnidirectional Approach Lighting System Consists of seven omnidirectional flashing lights located in the approach area of a nonprecision runway. Five lights are located on the runway centerline extended with the first light located 300 feet from the threshold and extending at equal intervals up to 1,500 feet from the threshold. The other two lights are located, one on each side of the runway threshold, at a lateral distance of 40 feet from the runway edge, or 75 feet from the runway edge when installed on a runway equipped with a VASI.
ODP
Obstacle Departure Procedures.
OEI
One Engine Inoperative.
Off Course
A term used to describe a situation where an aircraft has reported a position fix or is observed on radar at a point not on the ATC-approved route of flight.
Off-Airway Routes
The FAA prescribes altitudes governing the operation of aircraft under IFR for off airway routes in a similar manner to those on federal airways, jet routes, area navigation low or high altitude routes, and other direct routes for which an MEA is designated.
Off-Route Obstruction Clearance Altitude (OROCA)
An off-route altitude that provides obstruction clearance with a 1,000 foot buffer in non-mountainous terrain areas and a 2,000 foot buffer in designated mountainous areas within the U.S. This altitude may not provide signal coverage from ground based navigational aids, air traffic control radar, or communications coverage.
Off-Route Vector
A vector by ATC which takes an aircraft off a previously assigned route. Altitudes assigned by ATC during such vectors provide required obstacle clearance.
Offset Parallel Runways
Staggered runways having centerlines which are parallel.
OM
Outer Marker.
Omission error
The failure to anticipate significant instrument indications following attitude changes; for example, concentrating on pitch control while forgetting about heading or roll information, resulting in erratic control of heading and bank.
Omission error
The failure to anticipate significant instrument indications following attitude changes; for example, concentrating on pitch control while forgetting about heading or roll information, resulting in erratic control of heading and bank.
On Course
A. Used to indicate that an aircraft is established on the route centerline.
B. Used by ATC to advise a pilot making a radar approach that his/her aircraft is lined up on the final approach course.
On-Course Indication
An indication on an instrument, which provides the pilot a visual means of determining that the aircraft is located on the centerline of a given navigational track, or an indication on a radar scope that an aircraft is on a given track.
One-Minute Weather
The most recent one minute updated weather broadcast received by a pilot from an uncontrolled airport ASOS/AWSS/AWOS.
One-Minute Weather
The most recent 1-minute update weather broadcast based on ASOS/AWOS measurements and available to a pilot from an uncontrolled airport ASOS/AWOS.
Operate
With respect to aircraft, use, cause to use or authorize to use aircraft, for the purpose (except as provided in §91.13 of this chapter) of air navigation including the piloting of aircraft, with or without the right of legal control (as owner, lessee, or otherwise).
Operational control
With respect to a flight, the exercise of authority over initiating, conducting or terminating a flight.
Operations Specifications (OpsSpecs)
A published document providing the conditions under which an air carrier and operator for compensation or hire must operate in order to retain approval from the FAA.
Opposite Direction Aircraft
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°.
OpsSpecs
Operations Specifications
Optical illusion
A misleading visual image. For the purpose of this handbook, the term refers to the brains misinterpretation of features on the ground associated with landing, which causes a pilot to misread the spatial relationships between the aircraft and the runway.
Optical illusion
A misleading visual image. For the purpose of this handbook, the term refers to the brain’s misinterpretation of features on the ground associated with landing, which causes a pilot to misread the spatial relationships between the aircraft and the runway.
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.
Orientation
Awareness of the position of the aircraft and of oneself in relation to a specific reference point.
Orientation
Awareness of the position of the aircraft and of oneself in relation to a specific reference point.
OROCA
An off-route altitude which provides obstruction clearance with a 1,000 foot buffer in nonmountainous terrain areas and a 2,000 foot buffer in designated mountainous areas within the United States. This altitude may not provide signal coverage from ground-based navigational aids, air traffic control radar, or communications coverage.
Orographic
Of, pertaining to, or caused by mountains as in orographic clouds, orographic lift, or orographic precipitation.
Orographic Cloud
A cloud that usually results from air flowing upslope from terrain and being cooled adiabatically.
Otolith organ
An inner ear organ that detects linear acceleration and gravity orientation.
Otolith organ
An inner ear organ that detects linear acceleration and gravity orientation.
OTS
Out of service
Out
The conversation is ended and no response is expected.
Outer Area (Associated With Class C Airspace)
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 the 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 (LOM)
A compass locator installed at the site of the outer marker of an instrument landing system.
Outer Fix
A general term used within ATC 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
A marker beacon at or near the glideslope intercept altitude of an ILS approach. It is keyed to transmit two dashes per second on a 400 Hz tone, which is received aurally and visually by compatible airborne equipment. The OM is normally located four to seven miles from the runway threshold on the extended centerline of the runway.
Outside air temperature (OAT)
The measured or indicated air temperature (IAT) corrected for compression and friction heating. Also referred to as true air temperature.
Outside Air Temperature (OAT)
The measured or indicated air temperature outside the aircraft that is uncorrected.
Over
My transmission is ended; I expect a response.
Over-the-top
Above the layer of clouds or other obscuring phenomena forming the ceiling.
Overboost
A condition in which a reciprocating engine has exceeded the maximum manifold pressure allowed by the manufacturer. Can cause damage to engine components.
Overcontrolling
Using more movement in the control column than is necessary to achieve the desired pitch-and bank condition.
Overcontrolling
Using more movement in the control column than is necessary to achieve the desired pitch-and-bank condition.
Overhead question
In the guided discussion method, a question directed to the entire group in order to stimulate thought and discussion from the entire group. An overhead question may be used by an instructor as the lead-off question.
Overpower
To use more power than required for the purpose of achieving a faster rate of airspeed change.
Overpower
To use more power than required for the purpose of achieving a faster rate of airspeed change.
Overseas air commerce
The carriage by aircraft of persons or property for compensation or hire, or the carriage of mail by aircraft, or the operation or navigation of aircraft in the conduct or furtherance of a business or vocation, in commerce between a place in any State of the United States, or the District of Columbia, and any place in a territory or possession of the United States; or between a place in a territory or possession of the United States, and a place in any other territory or possession of the United States.
Overseas air transportation
The carriage by aircraft of persons or property as a common carrier for compensation or hire, or the carriage of mail by aircraft, in commerce:
(1) Between a place in a State or the District of Columbia and a place in a possession of the United States; or
(2) Between a place in a possession of the United States and a place in another possession of the United States; whether that commerce moves wholly by aircraft or partly by aircraft and partly by other forms of transportation.
Overspeed
A condition in which an engine has produced more r.p.m. than the manufacturer recommends, or a condition in which the actual engine speed is higher than the desired engine speed as set on the propeller control.
Overtemp
A condition in which a device has reached a temperature above that approved by the manufacturer or any exhaust temperature that exceeds the maximum allowable for a given operating condition or time limit. Can cause internal damage to an engine.
Overtorque
A condition in which an engine has produced more torque (power) than the manufacturer recommends, or a condition in a turboprop or turboshaft engine where the engine power has exceeded the maximum allowable for a given operating condition or time limit. Can cause internal damage to an engine.
Ozone
An unstable form of oxygen; heaviest concentrations are in the stratosphere; corrosive to some metals; absorbs most ultraviolet solar radiation.
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