Path Planning; Path Planning Considerations - Telephonics RDR-1600 Pilot's Manual

Weather Operations (Cont.)

6.6 PATH PLANNING

Remember to plan a deviation path early. Simply skirting the red portion of
a cell is not enough. Plan an avoidance path for all weather echoes which
appear beyond 100 miles since this indicates they are quite intense.
The most intense echoes are severe thunderstorms. Remember that hail
may fall several miles from the cloud, and hazardous turbulence may
extend as much as 20 miles from the storm. Avoid the most intense echoes
by at least 20 miles, that is, echoes should be separated by at least 40
miles before you fly between them. As echoes diminish in intensity, you can
reduce the distance by which you avoid them.

6.6.1 Path Planning Considerations

• Avoid cells containing red areas by at least 20 miles.
• Do not deviate downwind unless absolutely necessary. Your chances of
encountering severe turbulence and damaging hail are greatly reduced
by selecting the upwind side of the storm.
• If looking for a corridor, remember corridors between two cells containing
red areas should be at least 40 miles wide from the outer fringes of the
radar echo.
+
Do not approach a storm cell containing red any closer than 20 nm.
Echoes should be separated by at least 40 nm before attempting
to fly between them.
Figure 6.6.1-1. Penetration of Weather
When a complete detour is impractical, penetration of weather patterns may
be required. Avoid adjacent cells by at least 20 miles.
28 RDR-1600 Pilot's Guide
Note
TM106101(8/01)
Figure 6.6.1-2. Minimizing Doglegging
Cells beyond 75 miles are areas of substantial rainfall; do not wait for
red to appear. Plan and execute evasive action quickly to minimize
"doglegging."
Figure 6.6.1-3. "Blind Alley" or "Box Canyon" Situations
A "Blind Alley" or "Box Canyon" situation can be very dangerous when view-
ing the short ranges. Periodically switch to longer range displays to
observe distant conditions. As shown above, the short-range returns show
an obvious corridor between two areas of heavy rainfall, but the long-range
setting shows a larger area of heavy rainfall.
RDR-1600 Pilot's Guide
TM106101(8/01)
Weather Operations (Cont.)
29