III.F. Aviation Weather Hazards Flashcards
(13 cards)
What are the three stages of thunderstorm development?
Cumulus - Rising air
Mature - Strengthening up and down drafts. Precipitation begins.
Dissipating - Downdrafts dominate, rains itself out.
What are the three principal types of thunderstorms?
Single Cell
Multicell
Supercell
When flying around convective weather, what are some methods to avoid thunderstorms or the turbulence associated with thunderstorms?
a. NEXRAD for route selection strategy (just remember image may be 15 to 20 minutes old)
b. Listen to chatter on the ATC frequency for PIREPs or deviation requests.
c. Notice buildups out your window. Avoid by at least 20 miles any thunderstorm giving an intense radar echo. This is especially true under the anvil of a large cumulonimbus.
i. Remember that vivid and frequent lightning indicates the probability of a severe thunderstorm.
Give some examples of charts and reports useful in determining the potential for and location of thunderstorms along your route.
a. Convective Outlook (AC)— areas of slight, moderate, or high risk of severe thunderstorms for a 24-hour period.
b. Significant Weather Chart (SIGWX)
c. Weather radar
d. Convective SIGMETs (WST)
e. Pilot reports (PIREPs)
What are microbursts?
Intense downdrafts which, on reaching the surface, spread outward in all directions from the downdraft center.
Where are microbursts most likely to occur? And what is a clue of its existence?
a. Anywhere there is convective activity. They may be embedded in heavy rain or in light rain or virga.
b. A ring of blowing dust may be the only visual clue of its existence.
Where is wind shear likely to occur?
It may occur at any level in the atmosphere but three areas are of special concern:
a. Wind shear with a low-level temperature inversion;
b. Wind shear in a frontal zone or thunderstorm; and
c. Clear air turbulence (CAT) at high levels associated with a jet stream or strong circulation.
While on a cross-country flight, you notice a lens-shaped cloud over a mountainous area along your route of flight. What does the presence of this type of cloud indicate?
Mountain Wave turbulence
What is clear air turbulence (CAT)?
Clear air turbulence is defined as “sudden severe turbulence occurring in cloudless regions that causes violent buffeting of aircraft.”
Often associated with upper level wind shear from the jet stream, or mountain wave.
What is the most dangerous type of icing?
Clear ice, also known as rain ice. It usually happens when you’re flying through freezing rain, where raindrops spread out and freeze upon hitting the cold surface of your airplane.
The appearance of ice pellets is a sign that freezing rain might be present at higher altitudes. These are formed when rain falls from warmer air and freezes as it passes through colder air on the way down.
What are the three types of icing?
Clear (0C to -10C)
Rime (-10C to -20C)
Mixed (Combination of both)
What is the difference between “known” and “forecast” icing conditions?
“Known” icing conditions refer to situations where ice formation is actually detected or observed by a pilot (PIREP)…
While “forecast” icing conditions refer to situations where a pilot reasonably expects icing to form based on weather forecasts and other available information.
You picked up some ice on your windshield and wings during descent to landing. Your aircraft is not equipped for flight into known icing. What are some considerations on your final approach?
- Be prepared for significantly higher power requirements, higher approach and stall speeds, and a longer landing roll.
- Leave wing flaps RETRACTED. With a severe ice build-up on the horizontal tail, the change in airflow caused by wing flap extension could result in a loss of elevator effectiveness.
- Use defrost. Also open left window and, try to scrape ice from the windshield for visibility.
- Might need to forward slip for improved visibility.
- FILE A NASA ASRS REPORT ON THE GROUND
