Flight Techniques in the Vicinity of Thunderstorms

CHAPTER FOUR

AVIATION WEATHER

A pilot with airborne weather radar should remember that radar does not eliminate the hazards of

the thunderstorm. It merely helps to locate the most severe conditions. Since the radarscope

indicates only precipitation areas within thunderstorms, hazards can be encountered even in soft

spots. Thunderstorms having frequent, vivid lightning discharges are especially dangerous.

Airborne weather radar should be used as an avoidance rather than penetration tool. The pilot

should take time to properly evaluate scope indications and watch for trends in order to avoid the

most intense echo patterns. The pilot without airborne weather radar should make no attempt to

find soft spots on the basis of radar information not current up-to-the-minute.

408.

FLIGHT TECHNIQUES IN THE VICINITY OF THUNDERSTORMS

Since thunderstorms have so many potential hazards, it is appropriate to list some recommended

practices for pilots who must cope with these "uninvited guests." As far as flying is concerned,

there is no such thing as a small thunderstorm, so some common sense recommendations are

provided below:

If at all possible, avoid thunderstorms.

Do not venture closer than 20 miles to any storm cloud with overhanging anvils because of

the possibility of encountering hail.

Do not attempt to fly under thunderstorms in mountainous regions even if the area on the

other side of the mountains can be seen. Strong enough winds providing the lifting action to

produce the thunderstorms can also create extreme turbulence between mountain peaks.

If at all possible, avoid flying under thunderstorms because updrafts and downdrafts can

exceed the performance of the aircraft.

Do not take off or land if a thunderstorm is approaching. Sudden wind shifts or

microbursts can cause control problems.

Do not fly into a cloud mass containing scattered embedded thunderstorm without airborne

radar. Radar is necessary to "see" storms in the cloud mass. Scattered thunderstorms can be

circumnavigated visually unless they are embedded.

To avoid lightning do not penetrate a thunderstorm or fly through the cirrus anvil of a well-

developed or dissipated thunderstorm. Aircraft should also avoid clouds downwind of

thunderstorms.

The brighter and more frequent the lightning, the more severe the thunderstorm.

Regard any thunderstorm with tops 35,000 feet or higher as severe.

Avoid thunderstorms if at all possible using the following recommendations, listed in order of

priority:

Fly around (circumnavigate) the storm.

Fly over the top of the storm.

4-12 Thunderstorms