Hazardous Flashcards
Describe the formation of airframe icing
Glaze - formed by liquid water droplets that are large, numerous, and relatively warm. Upon contact with the aircraft skin, a portion of the liquid freezes, while the release of latent heat during the freezing process slows subsequent freezing. Resulting in a clear, smooth layer of ice. The surface may eventually develop ridges and horns on the LE of the wing.
Rime - formed by much colder liquid water droplets which are smaller and less numerous. Upon contact with the aircraft skin they freeze almost instantaneously, trapping pockets of air within the ice giving it a white appearance and making it brittle. Because the droplets are small, little latent heat is released during the freezing process and it is not slowed.
Mixed - occurs in mid temp ranges, in clouds with a variety of sized SCWD such as CU and ST type cloud formed together (embd). This is most dangerous as it appears as though there is just rime ice formed on the LE but the flow back will have formed a sheet of clear ice above and below.
Hoar frost - when moist air comes into contact with a surface at temperatures below 0 degrees. Water vapour deposits into ice onto the airframe.
Describe the atmospheric & meteorological conditions associated with (a)
clear ice (b) rime ice (c) mixed ice and (d) hoar frost
clear ice
- Cb, TCu, Ns, Lenticular
- -5 to -8 degrees
- 2500-4500ft abv FZL
- moist air, forced lifting
mixed ice
- As, Ac, Ns, Cb
- -10 to -30 degrees
- 5000-7500 abv FZL
- cold fronts, moist/cold air
rime ice
- As, Ac, Sc, St
- -15 to-30 degrees
- 7500-15000ft abc FZL
- warm fronts
Define the factors that increase the rate of ice accretion on aircraft in
flight
- larger droplets, more ice
- more droplet, more ice
- faster speed, more ice (to the point that frictional heating prevents ice formation)
- aircraft design, areas which act to trap SCWD, more ice
Describe airframe icings impact on aircraft operations
decreased thrust
decreased lift
increased weight
increased drag
Describe the impact of volcanic ash on aircraft operations
Describe (a) dust storms (b) blizzards (c) white – visual illusion type (d)
sector white out
Blizzards - snow being lifted from the surface and reducing low level vision significantly
White out - visual illusion where overcast conditions form or move over a snow covered surface. The result is all parts of the sky and ground being illuminated to the same extent and subsequently a lack of contrast between he surface and sky even in perfect visibility.
Can either be visual illusion type which is the whole sky, or sector white out which is where only a section of the sky has cloud cover and therefore only that direction produces the illusion.
Define (a) Corpuscular radiation (b) solar wind (c) heliosphere
corpuscular radiation - minute particle radiation emitted by the sun, consists of charged atoms and sub-atomic particles (primarily protons and electrons) which form magnetised plasma (gas) that travels away from the sun
solar wind - created by emission of corpuscular radiation by the sun. Temperature difference between the suns upper atmosphere and interplanetary space drives the solar wind outward from the sun in anti-clockwise in a pattern called an archimedes spiral
heliosphere - region of space where the solar wind expands out from the sun into the solar system carrying the suns magnetic field with it
Describe (a) coronal holes (b) coronal mass ejections (c) solar flares
coronal hole - large dark area on the surface of the sun representing lower coronal density, they are areas of unipolar magnetic fields that extend far out into the solar system allowing a continuous flow of high speed solar wind in the years following a solar maximum
CME - hot coronal material ejected from the sun during periods of reconfiguration of the magnetic field, reaching speeds of 1000-5000km/sec they produce large shockwaves ahead of them which can cause disruption to the earth magnetic field and to satellites
solar flares - occur during times of instability within the suns magnetic field, close to or at the solar max, where lines of magnetic field become detached from the surface. The lines move and interfere with each other and eventually cannot reconnect with the surface so the plasma energy within the lines get shot out to space in the form of a solar flare.
Effects of space weather
Degrade HF comms
Damage satellites
Interfere with GPS and satellite comms
Disrupt ground based electrical systems
Degrade anti corrosion protection on pipelines
Radiation damage for astronauts/airline crew/pax
Define the World Area forecast system
forecasting and reporting of upper atmospheric conditions and significant weather hazards
CAT
turbulence resulting from horizontal or vertical wind shear in a short distance and in the absence of visual clues, often associated with jets streams
Turbulence vs up/down draughts
turbulence typically causes abrupt movement in the aircraft resulting in involuntary roll/pitch/yaw
up/down draughts usually are associated with wave motions and while they can be strong enough to push aircraft up or down at an uncontrollable rate they are typically smooth
Hazards of visual illusion whiteout/sector whiteout
Loss of perspective
Reduced horizon definition
False horizons
Lack of shadows/contrast
Loss of depth perception
Loss of sense of direction
Vertigo
Spatial disorientation
Factors affecting wavelength
Wind speed and stability
Wavelength will increase with increased wind speed and decreased stability
Factors affecting amplitude
Wind speed and topography of updrafting slope
Can also be influenced by stability, a stable layer near ridge height reducing amplitude
