Met Flashcards
effects of icing
aerodynamic weight flying controls vision vibration blocked instruments undercarriage engine ice
For ALM main consideration is struts and general risks associated with ice
what are the six types of icing
clear (slow forming, forging horns on leading edges and is very adhesive)
Rime (brittle so breaks off so no real problem)
packed snow
rain ice
hoar frost
engine ice (+5 danger zone, air pressure drops to around 0 degrees)
effects of icing on an aircraft
aerodynamics increased weight control surfaces stick or jammed pitot tubes blocked undercarriage extension retraction problems engine intakes blocked communication is affected vision reduced possible vibrations due to uneven loading
Delays departures due to time it takes to de-ice.
On A400M it’s difficult to clear from tailplane due to its height.
How does temperature affect Aircraft Operations?
# Engine performance (including WAT limits). # Icing
how does wind direction affect Aircraft Operations
deciding factor for which runway to use (aircraft take off and land into wind)
cross wind limitations
limitations operating aircraft ramp, door and stabilisers struts
factors affecting severity of ice
droplet size
aircraft speed
aerofoil shape
temperature just Below Zero
how is fog / mist created
as air cools below saturation point it creates mist and can be dispersed by heat or wind
(radiation or advection)
What are the 2 most common types of fog in the U.K.?
Radiation fog
Advection fog
what is radiation fog
very common type of fog, it is most prevalent during the autumn and winter
Forms overnight as the air near the ground cools and reaches saturation point
This type of fog requires clear skies and high humidity, with little or no wind.
Can be dispersed by the sun, wind or dry air
what is advection fog
Forms when warm and moist air is blown across a cooler surface (land or water)
dispersed only when dry air replaces the humid air.
Examples of advection fog include San Francisco
What is a METAR?
An hourly or half hourly observed weather conditions report and can include a trend
what is a TAF
is a forecast valid for 9 hours updated every 3 hours
in weather collection what is a SPECM and SPECB
SPECM Manky
SPECB Better
what is a warm front
usually between 300-600 miles wide
slow moving and rises above cold front causing cloud development (due to frontal lifting)
What are the trigger actions for clouds?
convection
orographic uplift
mass ascent / descent
mechanical turbulence -
what is dew point
the temperature at which air would become saturated
what is buy ballots law
if the wind is in your back then low pressure is on your left
ice general information
ice needs a nucleus for water molecules to form
range for icing is + 52 - 20 degrees centigrade
freezing rain falls as water but as it hits an air frame forms ice
what is an occluded front
cold front advancing through warm front until it reaches the next cold front
this forces the warm front to rise, this causes a triple point and is associated with heavy rain
as the warm front is lifted the occluded front slowly loses its energy and peters out
what is a cold front
usually between 50-100 miles wide
fast moving and advances underneath the warmer front
this causes warm air to rise and thus cloud development
what is a temperature inversion
a layer of warm air trapped between cooler layers
trapped pollutants can cause haze
flying above can give problems with horizontal visibility
flying below can cause ducting which causes trapping of radar waves and increasing their range
How can you get a negative dew point?
Anegative dew pointsimply means the air is dry enough that it would havetobe cooledtothat very low temperature, in ordertocause moisturetobegintocondense out as ice crystals or supercooled water droplets.
