Visual Approach Slope Indicator

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 miles) during the day and up to 32 kilometers (20 miles) or more at night.

Types

tandard VASI

Basic visual approach slope indicators consist of two sets of lights. One set marks the start of the runway, while the other is set up some seven meters (twenty feet) along the runway. Each set of lights is designed so that the lights appear as either white or red, depending on the angle at which the lights are viewed. When the pilot is approaching the lights at the proper angle, meaning he is on the glide slope, the first set of lights appears white and the second set appears red. When both sets appear white, he is flying too high, and when both appear red he is flying too low. This is the most common type of visual approach slope indicator system.

PAPI "(Precision Approach Path Indicator)

Precision Approach Path Indicator consist of four sets of lights in a line perpendicular to the runway, usually mounted to the left side of the runway. These have a similar purpose to basic visual approach slope indicators, but the additional lights serve to show the pilot how far off the glide slope the aircraft is.
When the lights show White-White-Red-Red the aircraft is on the correct glide slope for landing, usually 3.0°. Three red lights (White-Red-Red-Red) indicate that the aircraft is slightly below glide slope (2.8°), while four red lights (Red-Red-Red-Red) indicate that the aircraft is significantly below glide slope (<2.5°).
Conversely, three white lights (White-White-White-Red) indicate that the aircraft is slightly above glide slope (3.2°), and four white lights (White-White-White-White) indicated that the aircraft is significantly above glideslope (>3.5°).
Most large airports utilize this system. Although most airports use a PAPI based on a 3.0° glide slope, some airports may use a glide slope as great as 4.5° in order to have proper obstruction clearance.

PVASI "(Pulsating Visual Approach Slope Indicator)"

PVASI is a single box found at non FAA Part 139 airports, heliports or airparks. The signal format is solid white when established on the proper descent profile, and solid red when below the proper descent profile. An active pulsing white light is seen when well above or pulsing red when well below. This allows the pilot to determine his position and rate of deviation or correction within the signal format and therefore determine the corrective action needed to return to the proper descent profile. Although PVASI is a single box system, its signal was evaluated by the U.S. Air Force and found to be much more accurate that VASI and equivalent to the four box PAPI.

Tri-colored VASI

This is a single light that appears amber above the glide slope, green on the glide slope and red below it. It is rarely used, partly because pilots who are unfamiliar with them have been known to misinterpret the lights, causing them to 'correct' in the wrong direction.

Mnemonics

Pilots often use mnemonics to help them remember basic information. In English, the following are common:
* Red over white, you're all right.
* White over white, you're out of sight.
** Alternative: White over white, you'll fly all night.
** Alternative: White over white, you're high as a kite.
** Alternative: White over white, you remain in flight.
* Red over red, you're dead.
** Alternative: Red over red, watch your head.
**Red over Red: hit the bed.Also
*Red red you're dead
*Red and white you're alright
*White and white you're as high as a kiteAlso
*Two whites, you're light; two reds, you're dead.

References

[http://www.faa.gov/airports_airtraffic/air_traffic/publications/atpubs/aim/Chap2/aim0201.html FAA Aeronautical Information Manual, Chapter 2 (Aeronautical Lighting and Other Airport Visual Aids), Section 1 (Airport Lighting Aids)] Alternative: White over White - too much height

ee also

* Pilot Controlled Lighting (PCL)
* Precision Approach Path Indicator (PAPI)
* Runway End Identification Lights (REIL)
* Runway Edge Lights (HIRL, MIRL, LIRL)
* Approach Lighting System (ALS)

External links

* [http://www.faa.gov/ATpubs/AIM/ FAA Aeronautical Information Manual]


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • 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

  • 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… …   Aviation dictionary

  • 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

  • Slope — (eng.: Steigung) steht für Course Rating und Slope, Golfbegriff Dual Slope Verfahren, Funktionsprinzip eines ADUs Visual Approach Slope Indicator (VASI) optisches System für Piloten Slippery Slope Argument, rhetorischer Begriff Clapeyron Slope,… …   Deutsch Wikipedia

Share the article and excerpts

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