severe in top 2/3 of the cell (Figure 4-13). However, with the strong updrafts and downdrafts,
adequate terrain clearance should also be considered in the selection of a penetration level.
When crossing a line of thunderstorms (a squall line for example), attempt to determine the
orientation of the line and penetrate the line at right angles (Figure 4-14). During the penetration
of a thunderstorm, do not attempt to turn back once you are inside the storm. Remember, single-
cell thunderstorms are only about one to five miles in diameter, and turning around will only
increase your time in the storm. Turning around can also result in a pilot becoming disoriented
and flying in the storm for a considerably longer period of time than continuing directly through
the storm in the first place. With no other information to make a decision, a penetration altitude
between 4000 and 6000 feet AGL should be adequate.
Figure 4-13 Through the Thunderstorm
Figure 4-14 Thunderstorm Penetration