Instrument Flight
Flight Procedures
For radial intercepts from arcs less than approximately 10 DME , an adjustment must be applied to the
arc-to-radial formula to compensate for turns outbound (less than 90 degrees) and turns inbound (greater
than 90 degrees) according to the formula:
90 + LEAD (radials)
90
x (TURN RADIUS)
Approximate Lead in Radials for Arcing Around a NAVAID at 10 DME or Less:
ARC DME
90 DEGREE LEAD
INBOUND LEAD
OUTBOUND LEAD
(>90 DEGREE LEAD)
(<90 DEGREE LEAD)
20
7.5
N/A
N/A
15
10
N/A
N/A
a18 (7/6)
a13 (5/6)
10
15
~
~
a27 (6/5)
a16 (3/4)
7
21
~
~
a40 (4/3)
a20 (2/3)
5
30
~
~
NOTE: Correction factor in parenthesis is calculated from the formula:
[90 +/- LEAD (radials)]/90 X (TURN RADIUS)
Point-to-Point Navigation
As you approach a terminal area, the controller may clear you either to a holding fix or to the IAF. When
cleared direct to a fix, you will have to use radar vectors or point-to-point navigation. Point-to-point
navigation allows you to fly directly from any fix (radial and DME) to any other fix within reception range of
a given station (Figure 25).
The following steps are used to accomplish the point-to-point procedure: First, tune and identify the
appropriate TACAN or VOR/DME equipped station. The aircraft HSI will function as a plotting board.
Visualize the HSI compass card as a compass rose with the station at the center. Picture the fix with the
greater distance on its radial at the outside edge of the HSI compass card. Visualize the fix with the
lesser distance (determined by the previous step) is placed at a proportional distance from the center of
the HSI on its radial. The aircraft is placed on the tail side of the radial the aircraft is on. Where on the
radial is determined by which fix is greater. If the aircraft is further away from the station than the Pt-to-Pt
target fix then the aircraft fix will be located where the tail of the bearing pointer crosses the compass
card. If closer, then the aircraft is located at a proportional point along the tail of the bearing pointer.
Once the fixes are determined, connect them with an imaginary line or with the aid of a straight instrument
such as a pencil. Move the line to the center of the HSI, paralleling the original imaginary line, and read
the course to the target fix where the line intersects the outside edge of the compass card. Turn the
aircraft to the new course and apply a WCH if known. Repeat the point-to-point procedure periodically en
route and make corrections to the target fix as needed.
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