Radial Inter Ception From an ARC

CHAPTER FOUR

T-6A INSTRUMENT NAVIGATION

Example: If you are inbound to the station at 150 KIAS and are instructed to arc at 10 DME,

you would begin the turn onto the arc at 10.8 DME. If you are outbound from the station and

desire to arc at 10 DME, your lead point would be 9.2 DME.

Turn. When the lead point is reached, turn in the proper direction to intercept the arc.

5. Monitor. Monitor the bearing pointer and range indicator during the turn and roll out with

the bearing pointer on or near the 90 index (wing-tip position).

6. Reference 90 index. Prior to the final roll out heading, evaluate your DME. If the aircraft

is positioned outside the arc, roll out with the bearing pointer above the 90 index; if inside the

arc, roll out with the bearing pointer below the 90 index.

RADIAL INTERCEPTION FROM AN ARC

Set. Set the desired course in the CDI.

2. Lead Point. Determine the lead point required in degrees. By using the 60:1 rule, we know

the following:

Distance From the Station

Radials/Miles

Radial Width (NM)

1.3

.75

.25

.17

6.7

.15

Example: If you are arcing to the east on the 12 DME arc at 120 KIAS (0.6 NM lead point) and

wish to intercept the 360 radial inbound, you would need a three radial lead point (Turn Radius

X Radials/Mile)(Figure 4-6).

3. Turn. When the lead point is reached, turn to intercept the selected course. Monitor the

CDI or bearing pointer during the turn and roll out on course or with a suitable correction to

course.

4-20 INSTRUMENT NAVIGATION