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turn the compass rose to the azimuth of the second fix and plot a point (measuring from the top line
again) representing the range of the second fix. Repeat for the successive fixes (Figure 7.18). To solve
for the wind, rotate the compass rose so that the three plotted lines are parallel to the vertical grid lines
and read the track under the true index of the compass rose. Then, determine the GS by measuring the
distance between the first and last plotted points using the grid lines. Using track and TH, find the DA
and use the standard MB-4 wind solution.
EXAMPLE:
TH = 320o Fix 1 310o 40 NM
TAS = 400 knots Fix 2 308o 30 NM
Time = 3 + 30 min Fix 3 305o 20 NM
Solution:
TC = 316o
GS = 352 knots
Wind = 349o/53 knots
7.22. Airborne Radar Approach (ARA). The ARA is as a ground controlled approach in reverse. It is
an alternate procedure in marginal weather conditions, normally when no other approach is available.
However, navigators should practice often to prepare for the time when it is the only way of making a
safe landing. Even during normal approaches, the navigator should monitor aircraft position both for
practice and as a backup to the regular approach.
7.22.1. During the ARA the navigator uses the radar to direct the aircraft to a point on the final approach
where the pilot can complete the landing visually.
7.22.2. There are two main phases in the ARA, the letdown and the approach itself. The letdown is
normally accomplished from a nearby VOR or TACAN station according to published procedures. If
these are not available, the navigator must pick a point on the extension of the runway that will provide
adequate time for descent and early alignment of the aircraft with the runway.
7.22.3. During the approach, the procedures vary with the capabilities of the radar. The navigator
provides headings, altitude calls, and distance-to-the-runway information for the pilots while fine tuning
the radar to break out the runway environment, approach lights, and runway itself. Terminal approach
plates should be used to locate possible hazards. On radars equipped with computers, use the crosshairs
to monitor the distance and direction to the end of the runway; otherwise, use the fixed range markers.
When using movable etched cursors for runway alignment reference, the landing environment moves
along the cursor if you are on course and heading. If the field return drifts from the cursor, turn the
aircraft. Remember to monitor drift angle (DA) changes due to wind shifts during descent.
192 AFPAM11-216 1 MARCH 2001
Figure 7.18. Target Timing Wind Solution.
7.22.4. Use caution when flying an ARA without backup NAVAIDs for orientation and when using an
AZ STAB setting other than north orientation. Be familiar with runway location and direction relative to
surrounding returns. It is possible to fly an apparently good approach to the field only to find that the
aircraft is over the threshold but considerably off the runway heading. Again, a point on the runway
extension should he used for initial alignment with the runway to avoid this problem. Consult the
appropriate aircraft tech order for procedures for each type of radar.
AFPAM11-216 1 MARCH 2001 193
7.23. Station Keeping. Station keeping is a technique using radar to maintain a fixed position within a
formation. Formations may require separations of a mile or more. At these distances, radar is more
precise than the visual method for staying in position. In addition, it is superior to the visual method of
formation flying because it is an all-weather method.
7.23.1. Maintain formation position with fixed or variable range markers or with the crosshairs. With
radars having directional pencil-type beam, returns appear on any portion of the scope. On others,
aircraft in the formation may appear in the altitude hole. To use the basic radar set for station keeping,
consider altitude separation, angular offset, and airspeed adjustments. The relative importance of each of
these considerations depends on the type of formation being flown. Basic tuning for station keeping is
best achieved by placing the antenna in pencil beam, adjusting the tilt to level, and setting AZ STAB in
the relative position.
7.23.2. In trail formations, the most important aspect of formation position is airspeed. Navigators in
follower aircraft must monitor formation position and adjust airspeed to stay in position. During a radio
silent mission, follower navigators must think as lead to compute the proper airspeed. It's not sufficient
to match the lead aircraft's airspeed. Compensation must also be made for altitude differences. As a
general rule, 3 knots of IAS decrease for every 500 feet above lead's altitude will usually keep true
　
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