JPATS Weather - NETC

JPATS AVIATION WEATHER BOOKLET
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:
1. If at all possible, avoid thunderstorms.
2. Do not venture closer than 20 miles to any storm cloud with overhanging anvils because of
the possibility of encountering hail.
3. Do not attempt to fly under thunderstorms in mountainous regions even if the area on the
other side of the mountains can be seen. Winds that are strong enough to provide the lifting
action to produce the thunderstorms can also create extreme turbulence between mountain peaks.
4. If at all possible, avoid flying under thunderstorms because updrafts and downdrafts can
exceed the performance of the aircraft.
5. Do not take off or land if a thunderstorm is approaching. Sudden wind shifts or microbursts
can cause control problems.
6. 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.
7. To avoid lightning do not penetrate a thunderstorm or fly through the cirrus anvil of a welldeveloped
or dissipated thunderstorm. Aircraft should also avoid clouds downwind of
thunderstorms.
8. The brighter and more frequent the lightning, the more severe the thunderstorm.
9. Regard any thunderstorm with tops 35,000 feet or higher as severe.
Thunderstorms should be avoided if at all possible using the following recommendations, listed
in order of priority of choice:
1. Fly around (circumnavigate) the storm.
2. Fly over the top of the storm.
3. Fly under the storm.
If it is not possible to avoid the storm(s) then,
4. Fly through the lower ⅓ of the storm.
When thunderstorms are isolated, they are easily circumnavigated provided the surrounding area
is clear of masking clouds. If lines of thunderstorms are present or if masking clouds obscure the
area around the storm, other techniques must be employed.
Version 3.2/Dec 08 5-9