How many miles should an area indicating a steep rainfall gradient be avoided at all altitudes?

The recommendation to avoid an area indicating a steep rainfall gradient by 20 miles is based on safety considerations associated with rapidly changing weather conditions that can accompany such gradients. These areas are often associated with turbulence, heavy precipitation, and the potential for severe weather phenomena, such as thunderstorms or microbursts, which can pose significant risks to flight operations.

Maintaining a distance of 20 miles from these regions allows pilots to enhance safety by reducing exposure to adverse weather effects, which can include unpredictable wind changes, reduced visibility, and other hazardous conditions. This buffer also provides pilots with a more manageable situation to detect and respond to any changes in weather, thereby allowing for better decision-making and increased situational awareness during flight operations.

In contrast, the other distances suggested in the options do not provide the same level of safety margin when it comes to avoiding the potentially dangerous effects of steep rainfall gradients. Therefore, adhering to the 20-mile avoidance recommendation helps ensure safer flight operations in varying weather conditions.