Precision Approach Aradar Approschy

INSTRUMENT NAVIGATION

PRECISION APPROACH RADAR_ APPROACH

Introduction - The precision approach radar (PAR) approach uses radar vice aircraft

equipment to maneuver the aircraft to a position for landing during conditions of low ceiling

and/or poor visibility. In the previous section, you were introduced to radar vectors to final

approach course. During this procedure, the approach controller used his radar capability to

direct your aircraft to a segment of a standard instrument approach procedure.

During a radar approach, the controller will direct your aircraft to a position from which you

can safely land. Radar approaches fall into two classes: (1) airport surveillance radar (ASR)

approaches which provide course and range information only and are thus non-precision

approaches (these use an MDA), (2) precision approach radar (PAR) approaches which provide

course, range and glideslope information and can thus be flown to lower minimums (using a

Decision Height) than ASR's.

The balance of this chapter will address PAR's only. The procedures for ASR's are similar.

Procedure

1. Preflight - Radar instrument approach minimums are published in tabular form in the

front of FLIP terminal instrument approach procedures (approach plates), providing information

regarding decision height, weather minimums, and glideslope angle. From glideslope angle and

ground speed the pilot can determine the rate of descent required to maintain glideslope on final

using the rate of descent table inside the backcover of the approach plates.

Familiarize yourself with this information as part of your preflight planning when a radar

approach (PAR or ASR) is available at your destination or alternate. Additional information

may be found in the ILS/RADAR section of the IFR Supplement entry.

Figure 21 is a sample of the section in the approach plates which contains information on radar

approaches. For the purposes of illustration we will consider the PAR approach to runway 22 at

MacDill AFB.

a. Under the heading of RADAR (1) is a list of frequencies on which your approach

may be conducted. The X's following the frequencies indicate that the radar site has the

capability to work on that frequency but does not monitor it continuously. The PAR approach to

runway 22 has a glideslope, GS(2), of 3.0 degrees. The threshold crossing height, TCH (3), is 52

feet. This means that if you are on gileslope, as you cross the runway threshold you will be 52

feet above the runway surface. If you remain on glideslope until touchdown you will land 1001'

down the runway point to interception, RPI (4).

b. The next column indicates that the published minimums for this approach apply to all

categories, CAT (5), of aircraft. Decision height, DH (6), is 114 feet in this case. Required

runway visual range, RVR (7), for the approach is 1600 Height above touchdown, HAT (8), is

100 feet. Ceiling and visibility, Ceil-Vis (9), for filing purposes and executing the approach is

100-1/4.

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INSTRUMENT DEPARTURES AND APPROACHES