Met: Hazards to flight Flashcards
List the four hazards to flight
- Volcanic activity
- Sand/Dust storms
- Blizzard
- Whiteout
What is the main cause for concern for volcanoes during flight?
Volcanic ash can be seen in satellite images, however NOT on the aircraft radar (due to it being dry)
What are the 12 hazards of volcanoes?
- Jet engine flameout (Due tiny glass particles in the air)
- Fan blade erosion and build up of ash in engine
- Blockage of pitot tubes
- Poor or nil radio reception
- Vis through windshield can be reduced to nothing (due pitting by glass particle)
- Contamination of engine oil
- Loss of cabin pressure
- St Elmos fire (blue electrical tendrils - occur in Cb also)
- Light dust can enter the cabin, looks like smoke, as well as an acrid smell which smells like electrical smoke
- Wet volcanic ash can make the RWY slippery
- paint can be stripped from a/c
- Dry ash on ground can also be sucked into engines.
What are the 5 types of volcanic alert system in NZ
- Volcanic alert system (run by GNS).
- The ICAO aviation colour code system
- Volcanic ash advisory message
- SIGMETs
- NOTAMs
Which two volcanoes are the only active ones in NZ?
- Ruapehu (1 on scale)
2. White island (1 on scale)
Avoidance and alleviation from volcanic activity
- Avoid in planning stage
- If ash is encountered in flight:
- Engines to idle if possible
- Exit cloud immediately
Define Blowing snow/blizzard
Consists of snow particles that are raised from the snow covered SFC via wind.
What is the threshold windspeed for blizzard to occur?
What does it depend on?
- Depends on temperatures/stability of atmosphere and size/shape of snow particles (therefore, the age and how dry the snow cover is)
- New snow: 10kts
- Old snow: up to 40kts required
What are the hazards of blizzards?
- Significant vis reductions to almost zero (only occur up to 100ft however due to stable layer)
- High winds
What conditions are associated with dust/sand storms?
Hot, dry environments, therefore unstable conditions are preferred for dust storms to occur.
Requirements for the development of dust storms? (4)
- Extended dry period
- Unstable atmosphere (which lifts dust to increased heights)
- strong SFC winds
- First two are enhanced by dry and cold fronts, which are both unstable with high winds, once their precip is dumped they are perfect initiators of dust storms.
Define Whiteout
An optical phenomenon that occurs due to diffuse illumination in uniformly overcast conditions over snow covered SFCs.
Define diffuse illumination
Light that comes from all directions and scatters with equal intensity as opposed to direct light.
Describe how whiteout occurs
- In absence of direct light, there are no shadows and contrast b/t objects is reduced.
- Our ability to ‘see’ relies on this and therefore our perception in 3D is what is limited.
What are the effects of whiteout on the observer (6)
- Lack of shadows/contrast/distance perception = Loss of perspective
- Reduced horizon definition/false horizons
- Loss of sense of direction
- Vertigo
- Spatial disorientation (trust your instruments!)
- Eye strain
