Precision Approach Radar
Overview
 
Precision approach radar (PAR) is a type of radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 guidance system designed to provide lateral and vertical guidance to an aircraft pilot
Aviator
An aviator is a person who flies an aircraft. The first recorded use of the term was in 1887, as a variation of 'aviation', from the Latin avis , coined in 1863 by G. de la Landelle in Aviation Ou Navigation Aérienne...

 for landing, until the landing threshold is reached. After the aircraft reaches the decision height (DH) or decision altitude (DA), guidance is advisory only. Controllers monitoring the PAR displays observe each aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

's position and issue instructions to the pilot that keep the aircraft on course and glidepath during final approach
Final approach (aviation)
A final approach is the last leg in an aircraft's approach to landing. In aviation radio terminology, it is often shortened to "final".In a standard airport landing pattern, which is usually used under visual meteorological conditions , aircraft turn from base leg to final within one to two miles...

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Encyclopedia
Precision approach radar (PAR) is a type of radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 guidance system designed to provide lateral and vertical guidance to an aircraft pilot
Aviator
An aviator is a person who flies an aircraft. The first recorded use of the term was in 1887, as a variation of 'aviation', from the Latin avis , coined in 1863 by G. de la Landelle in Aviation Ou Navigation Aérienne...

 for landing, until the landing threshold is reached. After the aircraft reaches the decision height (DH) or decision altitude (DA), guidance is advisory only. Controllers monitoring the PAR displays observe each aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

's position and issue instructions to the pilot that keep the aircraft on course and glidepath during final approach
Final approach (aviation)
A final approach is the last leg in an aircraft's approach to landing. In aviation radio terminology, it is often shortened to "final".In a standard airport landing pattern, which is usually used under visual meteorological conditions , aircraft turn from base leg to final within one to two miles...

. It is similar to an instrument landing system
Instrument Landing System
An instrument landing system is a ground-based instrument approach system that provides precision guidance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument...

 (ILS) but requires control instructions. One type of instrument approach that can make use of PAR is the ground-controlled approach
Ground-controlled approach
In aviation a ground-controlled approach , is a type of service provided by air-traffic controllers whereby they guide aircraft to a safe landing in adverse weather conditions based on radar images...

 (GCA). Air traffic controllers must transmit a minimum of every 5 seconds to the pilot their relation to the azimuth portion and, once intercepting the glidepath, their elevation. The approach is terminated when the aircraft reaches the OCA/H (Obstacle Clearance Altitude/Height). Nevertheless, information is provided till threshold and aircraft may be monitored by controller till touchdown. Controller in charge of PAR should not be responsible for any duty other than the PAR approach concerned.

The upper portion of the display indicates elevation, the lower portion azimuth. Controllers must be able to interpret radar returns for the azimuth as a "top view" to inform them if the aircraft is left or right of course.

Precision approach radars are most frequently used at military air traffic control
Air traffic control
Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...

 facilities. Many of these facilities use the AN/FPN-63, AN/MPN
AN/MPN
The AN/MPN is a mobile Ground-controlled approach radar first used during World War II. "MPN" is Joint Electronics Type Designation System nomenclature for Ground mobile , Radar , Navigation aid .-Variations:...

, or AN/TPN-22. These radars can provide precision guidance to a distance of 10 to 20 miles. The OJ-333 Radar scope is the indicator which the air traffic controller
Air traffic controller
Air traffic controllers are the people who expedite and maintain a safe and orderly flow of air traffic in the global air traffic control system. The position of the air traffic controller is one that requires highly specialized skills...

 uses to provide instructions to the pilots.

In the United States PAR are used mostly by The Navy. This is because they present a more covert type of precision approach for use on Aircraft carriers. An ILS installed on a ship could provide guidance to enemy missiles but a PAR does not provide accurate guidance with out controller instruction.

See also

  • Acronyms and abbreviations in avionics
    Acronyms and abbreviations in avionics
    -A:*ACARS: Aircraft Communications Addressing and Reporting System.*ACAS: Airborne Collision Avoidance System.*ACP: Audio Control Panel.*ACS: Audio Control System.*ADAHRS: Air Data and Attitude Heading Reference System.*ADC: Air Data Computer....

  • Instrument approach
    Instrument approach
    For aircraft operating under instrument flight rules , an instrument approach or instrument approach procedure is a series of predetermined maneuvers for the orderly transfer of an aircraft under instrument flight conditions from the beginning of the initial approach to a landing, or to a point...

  • Ground-controlled approach
    Ground-controlled approach
    In aviation a ground-controlled approach , is a type of service provided by air-traffic controllers whereby they guide aircraft to a safe landing in adverse weather conditions based on radar images...

  • AN/MPN
    AN/MPN
    The AN/MPN is a mobile Ground-controlled approach radar first used during World War II. "MPN" is Joint Electronics Type Designation System nomenclature for Ground mobile , Radar , Navigation aid .-Variations:...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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