The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night. Visibility is reported as statute miles, hundreds of feet or meters. (Refer to 14 CFR Part 91.) (Refer to AIM.)

1. Flight Visibility- The average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night.
2. Ground Visibility- Prevailing horizontal visibility near the earth's surface as reported by the United States National Weather Service or an accredited observer.
3. Prevailing Visibility- The greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle which need not necessarily be continuous.
4. Runway Visibility Value (RVV)- The visibility determined for a particular runway by a transmissometer. A meter provides a continuous indication of the visibility (reported in miles or fractions of miles) for the runway. RVV is used in lieu of prevailing visibility in determining minimums for a particular runway.
5. Runway Visual Range (RVR)- An instrumentally derived value, based on standard calibrations, that represents the horizontal distance a pilot will see down the runway from the approach end. It is based on the sighting of either high intensity runway lights or on the visual contrast of other targets whichever yields the greater visual range. RVR, in contrast to prevailing or runway visibility, is based on what a pilot in a moving aircraft should see looking down the runway. RVR is horizontal visual range, not slant visual range. It is based on the measurement of a transmissometer made near the touchdown point of the instrument runway and is reported in hundreds of feet. RVR is used in lieu of RVV and/or prevailing visibility in determining minimums for a particular runway.
6. Touchdown RVR- The RVR visibility readout values obtained from RVR equipment serving the runway touchdown zone.
7. Mid-RVR- The RVR readout values obtained from RVR equipment located midfield of the runway.
8. Rollout RVR- The RVR readout values obtained from RVR equipment located nearest the rollout end of the runway. (See FLIGHT VISIBILITY.) (See GROUND VISIBILITY.) (See RUNWAY VISUAL RANGE.) (See VISIBILITY.)

The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night.

1. Flight Visibility-The visibility forward from the cockpit of an aircraft in flight.
2. Ground Visibility-The visibility at an aerodrome as reported by an accredited observer.
3. Runway Visual Range [RVR]-The range over which the pilot of an aircraft on the centerline of a runway can see the runway surface markings or the lights delineating the runway or identifying its centerline.

• ICAO: The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night.
  1. Flight Visibility - The visibility forward from the cockpit of an aircraft in flight.
  2. Ground Visibility - The visibility at an aerodrome as reported by an accredited observer.
  3. Runway Visual Range (RVR) - The range over which the pilot of an aircraft on the centerline of a runway can see the runway surface markings or the lights delineating the runway or identifying its centerline.
• USA: The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night. Visibility is reported as statute or nautical miles, hundreds of feet or meters.
  1. Flight Visibility - The average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night.
  2. Ground Visibility - Prevailing horizontal visibility near the earth’s surface as reported by the United States National Weather Service or an accredited observer.
  3. Prevailing Visibility - The greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle which need not necessarily be continuous.
  4. Runway Visibility Value (RVV) - The visibility determined for a particular runway by a transmissometer. A meter provides a continuous indication of the visibility (reported in miles or fractions of miles) for the runway. RVV is used in lieu of prevailing visibility in determining minimums for a particular runway.
  5. Runway Visual Range (RVR) - An instrumentally derived value, based on standard calibrations, that represents the horizontal distance a pilot will see down the runway from the approach end; it is based on the sighting of either high intensity runway lights or on the visual contrast of other targets whichever yields the greater visual range. RVR, in contrast to prevailing or runway visibility, is based on what a pilot in a moving aircraft should see looking down the runway. RVR is horizontal visual range, not slant visual range. It is based on the measurement of a transmissometer made near the touchdown point of the instrument runway and is reported in hundreds of feet. RVR is used in lieu of RVV and/or prevailing visibility in determining minimums for a particular runway.
     1. Touchdown RVR - The RVR visibility readout values obtained from RVR equipment serving the runway touchdown zone.
     2. Mid-RVR - The RVR readout values obtained from RVR equipment located midfield of the runway.
     3. Rollout RVR - The RVR readout values obtained from RVR equipment located nearest the rollout end of the runway.