Aircraft Icing & Turbulence + PIREP Flashcards
What are the reporting categories for aircraft icing?
AIM 7-1-19
- Trace
- Light
- Moderate
- Severe
What effect does aircraft icing have on performance? ( 5 things, get them all right)
AIM 7-1-19
- Thrust is reduced
- Drag Increases
- Lift decreases
- Weight increases
- Result: Stall speed increases
*these effects are cumulative
Where can icing be expected?
AIM 7-1-19
Anywhere visible moisture or precipitation is present and the OTA is +2c to -10c
but can occur at +5c to -20c
What should you do if you encounter aircraft icing?
AIM 7-1-19
- Leave the area of visible moisture by turning around
- Leave the area of near freezing temps by descending OR climbing (temp inversion)
What should you do after you have successfully left an area where icing conditions have been encountered? (2 things)
AIM 7-1-19
- Let ATC know the type and severity of icing encountered
- Obtain an amended clearance with a new route away from the icing, or DIVERT if needed.
What is Trace icing, what is its rate of accumulation, and what action should be taken?
AIM 7-1-19
- Trace icing is when icing first becomes noticeable
- 1/4 inch per hour on outer wing
- Consider exiting icing conditions before they worsen
What is Light icing, at what rate does it accumulate, and what action should be taken?
AIM 7-1-19
- Light icing requires the occasional cycling of deicing systems
- 1/4 to 1 inch accumulation per hour
- Exit icing conditions
What is Moderate icing, at what rate does it accumulate, and what action should be taken?
- Moderate icing requires the FREQUENT cycling of deicing systems
- 1-3 inches per hour
- Exit icing conditions ASAP
What is Severe Icing, at what rate does it accumulate, and what action should be taken?
AIM 7-1-19
- Severe icing is occurring when ice protection systems fail to remove the ice and ice accumulates in areas normally not prone to icing
- More than 3 inches per hour
- Exit IMMEDIATELY, by regulation
What is Clear Ice?
1 . Glossy, translucent ice formed by the relatively slow freezing of large droplets.
- Clear ice forms as the droplets slowly freeze as they roll backwards on the surface of the aircraft
- Can forms horns that disrupt airflow
** MOST DANGEROUS **
*Usually form in warmer temps than Rime ice
What is Rime Ice?
Rough, milky, ice formed by the rapid freezing of supercooled droplets upon impact.
**Most common type.
**Rime ice gets its milky appearance from air bubbles trapped in-between the ice as it rapidly freezes
When are you most likely to encounter Rime Ice?
- Usually forms in colder temps
- In stable conditions like Stratus clouds
What is Mixed Icing?
- A mix of Clear and Rime ice that forms when flying through varying conditions of cold, and moisture.
- Can form horns
What is the most dangerous type of icing to encounter and why?
Clear Ice
- Heavy, adds weight
- Ice can accumulate behind where the de-icing equipment is installed
- Hard to see
- Forms horns that further disrupt the airflow
What are Super Cooled Water Droplets?
- Pure water that does not freeze until -20c, due to surface tension
- They will freeze instantly if sufficiently disturbed (like by an aircraft flying into them)
What are the two main categories of Aircraft Icing?
- Induction icing (engine)
- Airframe icing
At what temperatures will it be too cold for icing to occur and why?
- Usually less than -20c
- Because most water content is already frozen as ice crystals
At what temperatures are you mostly likely to encounter Rime, Clear, and Mixed icing respectively?
Rime = Temps less than -15c
Clear = 0c to -10c
Mixed = -10c to -15c
In Stratiform type clouds, what type of icing can you expect, and at what intensity, and what can be said about the thickness of the icing layer?
- Rime and Mixed
- Trace and light
- Generally, the icing layer in a Stratiform cloud is about 3,000-4,000ft thick, so climbing above it is an option.
In Cumuliform type clouds, what type of icing can you expect, and at what intensity, and where will the worst icing be?
- All types of icing
- All intensities
- Worst icing will occur near the top of the Cumuliform formation
What is the worst weather phenomenon to encounter in regards to aircraft icing?
Freezing rain
