Minimums
IFR takeoff Mins
part 91 - non
part 121,125,127,135 - 1-2 engines = 1sm vis
2+ engines = 1/2 sm vis
3 ingredients of a thunderstorm
- unstable air
- lifting action
- water vapor present in the air
AIRMET
- non convective significant weather valid for all craft but especially small craft
- valid 6 hours
- 3 types
S - IFR conditions, mountain obstructions
T - moderate turbulence
Z - moderate icing
what is required for ice to form
visible moisture and an aircrafts temp of below freezing
life cycle of a thunderstorms
cumulus
mature
dissipating
Alternate Mins
non precision - 800/2
precision - 600/2
no IAP then the forecasted conditions at the time arrival must allow for descent from the MEA, approach, and landing under VFR
Radiation fog
fog that forms on a calm, clear night when the ground cools rapidly
SIGMET
- non convective hazardous weather to all craft
- dust storms, volcanic ash, severe icing, severe turbulence,
- valid 4 hours
Structural icing
icing on structure of plane
3 types - rime, clear, mixed
how does frost affect the aircraft
the roughness of its surface spoils the smooth flow of air thus causing a slow- ing of the airflow
Approach category speeds and circling mins
B 90 to 120 1.5
C 121 to 140 1.7
D 141 to 165 2.3
E +165 4.3
Advection fog
warm air moves over a colder surface
Convective SIGMET
- convective weather valid for all craft
- thunderstorms, tornadoes, hail greater than 3/4 in
- valid 4 hours
Ice fog
when temps are below freezing causing water vapor to turn to ice
How does a H pressure system move and what weather is associated with it
- down, out, clockwise
- Stratiform clouds
- Fog
- Smooth air
- Bad visibility
When must we file an alternate
1-2-3 rule
when weather 1 hour before to 1 hour after is less than 2000 ceilings or 3sm vis
Steam fog
cold air moves over warm water
Surface analysis chart
Current weather
- shows high and low pressure systems
- shows warm and cold fronts
- Orange dashed lines are troughs or elongated area of low pressure
- valid 6 hours
Induction icing and instrument icing
induction is icing on aircrafts air ports or carburetor
instrument icing is icing on the pitot tubes or static ports
How does a L pressure system move and what weather is associated with it
- up, in, counter clockwise
- bad weather because of lifting action
- Cumuliform clouds
-Showery precip
-Rough air
-Good visibility
Visual approach and contact approach weather minimums
- visual = 3 sm vis and 1000 ft ceilings
- contact = 1 sm clear of clouds
moist air pushed up a mountain slope that cools rapidly
Low level significant weather chart
- forecasted weather
- significant weather conditions sfc to 24,000 ft
- red = IFR
- blue = MVFR
- orange = moderate turbulence (one triangle) severe turbulence (2 triangles)
- teal dashed = freezing levels above sea level
- teal wavy = freezing levels at the surface
how does icing affect the airplane
ice can modify the airflow around the aircrafts surfaces leading to a loss of lift, increase of drag and a shift in the airfoil center of pressure
- lines of equal pressure
- they show the pressure gradient and can show trends or how the pressure is moving
- close together means its windy, typically associated with L pressure