visual approach slope indicator

A system of lights arranged to provide visual descent guidance information during the approach to a runway. These lights are visible from 3 to 5 miles during the day and up to 20 miles at night. The visual glide path of the VASI provides a safe obstruction clearance within +/-10° of the extended centerline and up to 4 NM from the runway. A VASI installation may consist of 2, 4, 6, 12, or 16 light units arranged in bars referred to as near, middle, and far bars. Most VASI installations consist of two bars—near and far—and may consist of 2, 4, or 12 light units. Some VASIs consist of three bars—near, middle, and far—which provide an additional visual glide path to accommodate high-cockpit aircraft. This installation may consist of either 6 or 16 light units. VASI installations consisting of 2, 4, or 6 light units are located on one side of the runway, usually the left. Where the installation consists of 12 or 16 light units, the units are located on both sides of the runway. Two-bar VASI installations provide one visual glide path that is normally set at 3°. Three-bar VASI installations provide two visual glide paths. The lower glide path is provided by the near and middle bars and is normally set at 3°, whereas the upper glide path, provided by the middle and far bars, is normally 1/4 degree higher. This higher glide path is intended for use only by high-cockpit aircraft to provide a sufficient threshold crossing height. Although normal glide-path angles are 3°, angles at some locations may be as high as 4.5° to give a proper obstacle clearance. In most cases, an indication of red-red means below the glide path, white-white means above the glide path, and red-white means on the glide path. The various versions of VASI are the two-bar VASI, three-bar VASI, PAPI (precision approach path indicator), T-VASI, and AT-VASI.
Three-bar VASI.
Helicopter approach path indicator (HAPI).

Aviation dictionary. 2014.

Look at other dictionaries:

  • Visual Approach Slope Indicator — The Visual Approach Slope Indicator (VASI) is a system of lights on the side of an airport runway that provides visual descent guidance information during the approach to a runway. These lights may be visible from up to eight kilometers (five… …   Wikipedia

  • Visual Approach Slope Indicator — Das VASI (Visual Approach Slope Indicator) ist ein optisches System, welches die Piloten bei der Einhaltung des Gleitpfades im Anflug auf eine Landebahn unterstützt. Ein VASI ist für Flughäfen nicht zwingend vorgeschrieben. Das System zeichnet… …   Deutsch Wikipedia

  • abbreviated visual approach slope indicator system — A night landing aid placed at the beginning of a flare path or runway. It displays different colored lights, depending on the angle from which it is viewed by a pilot approaching to land. When viewed from the correct angle of safe approach, it… …   Aviation dictionary

  • tricolor visual approach slope indicator — A system of lights to indicate the correct glide slope when making an approach to a runway. It consists of a single light unit projecting a three color visual approach path. The below–glide path indication is red, the above–glide path indication… …   Aviation dictionary

  • visual glide-path indicator — A system of visible lights arranged in a pattern at the landing end of the runway to provide glide slope guidance for aircraft making a visual approach. A typical system consists of downwind and upwind bars, consisting of 2, 3, 4, or 12 lights on …   Aviation dictionary

  • Precision Approach Path Indicator — Das VASI (Visual Approach Slope Indicator) ist ein optisches System, welches die Piloten bei der Einhaltung des Gleitpfades im Anflug auf eine Landebahn unterstützt. Ein VASI ist für Flughäfen nicht zwingend vorgeschrieben. Das System zeichnet… …   Deutsch Wikipedia

  • Precision Approach Path Indicator — The Precision Approach Path Indicator (PAPI) is a light system positioned beside the runway that consists of two, three, or four boxes of lights that provide a visual indication of an aircraft s (fixed wing or rotor wing) position on the… …   Wikipedia

  • helicopter approach path indicator — A device similar to a VASI (visual approach slope indicator) used for fixed wing aircraft. The helicopter gets a steady green indication when it is on the desired glide slope. The indication is flashing green when it is above the glide slope, and …   Aviation dictionary

  • precision approach path indicator — A system of lights arranged to provide visual descent guidance information during the approach to a runway. The system is similar to the VASI (visual approach slope indicator). However, the light units are installed in a single row of either two… …   Aviation dictionary

  • stabilized glide slope indicator — An electrohydraulic optical landing aid for use on air capable ships. With it, a pilot can visually establish and maintain the proper glide slope for a safe approach and landing. The visual acquisition range is approximately 3 miles at night… …   Military dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.