Reference: AIR 2.7
Quick Thunderstorm Facts
-Severe turbulence may extend up to 20 NM from severe thunderstorms
-If there is an area of strong or very strong radar echoes separated by 40 N or less, and you choose a flight path through it, you will encounter severe turbulence
-Never underestimate the turbulence beneath a thunderstorm, especially when relative humidity is low (strong out-flow winds)
-Lightning strikes –> most likely operating at altitudes where temperatures are between -5 and +5.
-Radar shows echoes of light
-The best policy is avoiding thunderstorms
-Vivid/frequent lightning indicates severe activity in the TS
-Any TS with tops => 35000′ is severe
Flight Precautions: Avoiding a TS
-Don’t land/take-off when a TS is approaching
-Don’t fly under a thunderstorm (even if you can see through to the other side)
-If a TS is covering 5/8 or more of an area, avoid the area
-If a cloud mass contains embedded thunderstorms, don’t fly into the cloud mass (unless you have airborne radar)
-If there is a severe thunderstorm, a thunderstorm giving intense radar returns, or the anvil of a large cumulonimbus…..avoid by at least 20 NM
-Clear the top of a known/suspected severe thunderstorm by at least 1000′ altitude for each 10kt of wind speed at the cloud top.
Flight Precautions: If you cannot avoid an area of TS
Flight Precautions: If you enter a TS
-Concentrate on instruments
-Don’t change power setting
-Don’t attempt to keep a constant rigid altitude
-Don’t turn back
Quizzes
Flight in a thunderstorm
Flight near areas of thunderstorms
Questions:
1. We all know thunderstorms are bad…but why? Why are thunderstorms so bad to fly near/into?
2. Is there any correlation between the external visual appearance of a thunderstorm and the severity/amount of hail/turbulence associated with it?
3. There is severe thunderstorm on your route of flight. You are just within 20NM away. Might you experience severe turbulence?
4. Your boss wants to know if there are any thunderstorms along your route of flight planned for later. What weather products can you use to find areas of precipitation?
5. What would you be looking for exactly?
6. You’re trying to select an altitude at which you will most likely avoid lightning strikes. What temperatures will you want to avoid?
7. Can lightning strike aircraft flying in clear air in the vicinity of a thunderstorm?
8. What may happen to your aircraft if you are struck by lightning?
9. You accidentally enter a thunderstorm. Why is it best to concentrate on your instruments?
Answers:
1. They contain nearly all weather hazards known to aviation i.e. tornados, turbulence, icing, lightning, etc
2. No! The visible thunderstorm cloud is only a portion of the system. You could look at a thunderstorm and think “that doesn’t look too bad…” but be so fatally wrong.
3. Yes
4. Airborne or ground based weather radar reflect areas of precipitation
5. the frequency and severity of turbulence associated with areas of high water content increases the radar return.
6. Anything between -5 and +5.
7. Yes
8. Puncture the skin; damage electronic equipment; cause engine failure; induce permanent error in magnetic compass; engine water ingestion (for a turbine engine)
9. Looking outside increases the danger of temporary blindness from lightning
IFR Rating 