ATPL Meteorology - Class 9: Icing.
Summary
TLDRIn this meteorology class, Grant discusses aircraft icing, a significant hazard affecting flight dynamics. Icing occurs when aircraft encounter liquid water below freezing temperatures, leading to various ice types like hoarfrost, rime, and clear ice, each with distinct formation processes. These ice formations increase aircraft weight, alter aerodynamics, and can cause engine issues, impacting lift and power. The video outlines the conditions for icing, its effects on aircraft performance, and the importance of anti-icing measures.
Takeaways
- ✈️ Icing significantly impacts aircraft performance by adding weight and disrupting airflow over aerodynamic surfaces.
- ❄️ There are three main types of airframe icing: hoarfrost, rime ice, and clear ice, each formed under slightly different conditions.
- 🌀 Hoarfrost forms when water vapor sublimates directly to ice on the cold aircraft surface, similar to frost on a car window.
- ❄️ Rime ice occurs when small supercooled water droplets rapidly freeze on the aircraft's leading edges, creating a brittle structure.
- 🌟 Clear ice forms from larger supercooled water droplets that slowly freeze and spread, leading to a heavier and more uniform ice structure.
- 📈 Icing can cause an aircraft to become imbalanced due to the added weight, potentially leading to a loss of lift if the aircraft is near its maximum load.
- 🔧 Engine icing, including carburetor and intake icing, can restrict airflow and lead to a rich fuel mixture, reducing engine power output.
- 🌡️ Icing conditions typically occur below 10 degrees Celsius with visible moisture, and the type of icing can vary with temperature ranges.
- ☁️ In temperatures between 0 and -20 degrees Celsius, both large and small supercooled water droplets can cause a mix of rime and clear ice.
- ❄️ Below -40 degrees Celsius, supercooled water droplets are less likely to cause icing as they tend to freeze into solid particles that don't adhere well to the aircraft.
- 🛠️ Pilots should activate anti-icing systems when entering clouds at temperatures below 10 degrees Celsius and may turn them off below -40 degrees Celsius when icing conditions are less likely.
Q & A
What are the main challenges aircraft face due to icing?
-Aircraft face challenges due to added weight from ice and changes in the shape of aerodynamic surfaces, leading to disruption in airflow and potentially a loss of lift.
What is the difference between rime ice and clear ice?
-Rime ice forms from small supercooled water droplets and is brittle with many air bubbles, while clear ice forms from larger supercooled water droplets, is more uniform, and is heavier and harder to remove.
How does carburetor icing occur in piston engines?
-Carburetor icing occurs when fuel vaporization in the carburetor causes a temperature drop, leading to ice formation on the venturi tube walls, which restricts airflow and affects the fuel-to-air mixture.
What is the role of temperature in the formation of different types of ice on an aircraft?
-Temperature plays a critical role in determining the type of ice formed; rime ice is more common in warmer sub-zero temperatures, while clear ice is more likely in colder conditions.
How does the presence of ice affect an aircraft's lift and weight balance?
-Ice adds weight to the aircraft, requiring more lift to maintain balance. If the aircraft is near its maximum load, it might not be able to produce enough lift to counteract the added weight from ice.
What is the significance of the temperature range between -20 and -40 degrees Celsius for icing conditions?
-In this temperature range, there is a higher likelihood of encountering rime ice due to the predominance of small supercooled water droplets, which are more likely to freeze and form rime ice.
Why is it important for pilots to be aware of icing conditions when flying through clouds?
-Pilots need to be aware of icing conditions to manage the aircraft's anti-icing systems effectively, as clouds can contain supercooled water droplets that can lead to ice formation on the aircraft.
What is the impact of engine intake icing on jet engines?
-Engine intake icing can restrict the airflow into the engine, leading to an imbalance in the fuel-to-air mixture and a reduction in engine power output.
How does the sublimation of water vapor contribute to icing on an aircraft?
-Sublimation of water vapor directly to ice on the aircraft's surface can lead to hoarfrost, which is a type of icing that forms when the aircraft transitions from cold air to warmer, humid air.
What are the typical conditions for the formation of hoarfrost on an aircraft?
-Hoarfrost forms when an aircraft flies from a cold air mass into an area of warmer, higher humidity air, causing water vapor to sublimate directly onto the cold airframe.
How do the principles of flight relate to the problems caused by icing on an aircraft?
-The principles of flight, particularly the generation of lift and the balance of forces on an aircraft, are disrupted by icing, which alters the shape of the wings and other surfaces, leading to a loss of lift and an increase in drag.
Outlines
🛩 Introduction to Aircraft Icing
Grant introduces the ninth class in the meteorology series, focusing on the hazards of aircraft icing. Icing poses a significant threat to aviation as it adds substantial weight to the aircraft and alters the aerodynamic surfaces, disrupting airflow. The video builds upon the principles of contamination from the principles of flight series. Icing occurs when an aircraft encounters liquid water below freezing temperatures or when precipitation contacts a cold airframe. There are several types of icing, including hoarfrost, rime ice, and clear ice, each formed under slightly different conditions. Hoarfrost forms when water vapor sublimates directly onto the cold surface of the aircraft, similar to frost on a car. Rime ice forms when small supercooled water droplets rapidly freeze upon contact with the airframe, while clear ice forms from larger droplets that freeze more slowly, creating a denser and heavier structure. These ice types are more common in specific cloud types and temperature ranges.
🌡️ Types and Effects of Icing
This section delves into the various types of icing and their specific conditions. Hoarfrost forms when an aircraft transitions from cold air to warmer, more humid air, causing water vapor to sublimate onto the airframe. Rime ice is common in clouds with small supercooled water droplets, while clear ice is more prevalent in clouds with larger droplets, such as cumulonimbus clouds. The presence of ice on an aircraft leads to increased weight and altered aerodynamics, which can be critical if the aircraft is near its maximum load capacity. Engine icing is also discussed, with two main forms: carburetor icing and intake icing. Carburetor icing occurs when fuel vaporization in the carburetor causes a temperature drop, leading to ice formation that restricts airflow and affects the fuel-to-air mixture, reducing engine power. Intake icing affects both piston and jet engines, where ice restricts air intake and leads to an imbalance in the combustion process, also decreasing power output. The video explains the conditions under which these icing scenarios are likely to occur, such as temperatures and the presence of moisture in the air.
❄️ Icing Conditions and Anti-Icing Measures
The final paragraph discusses the operational considerations for pilots when encountering icing conditions. Icing is a concern below 10 degrees Celsius with visible moisture, as the aircraft's surfaces can cool significantly in flight, leading to ice formation. Between 0 and -20 degrees Celsius, both large and small supercooled water droplets can cause rime and clear ice, respectively. Below -20 degrees Celsius, the likelihood of rime ice increases as larger droplets have already frozen. At temperatures below -40 degrees Celsius, icing conditions are considered unlikely due to the formation of solid ice particles that are less likely to adhere to the aircraft. The video concludes with advice on when to activate anti-icing systems, suggesting that they should be turned on when entering clouds at temperatures of 10 degrees Celsius or lower and can be turned off once the temperature drops below -40 degrees Celsius. The summary underscores the importance of understanding and managing the risks associated with aircraft icing.
Mindmap
Keywords
💡Icing
💡Aerodynamic surfaces
💡Horfrost
💡Rime ice
💡Clear ice
💡Lift
💡Engine icing
💡Carburetor icing
💡Temperature bands
💡Anti-icing systems
Highlights
Icing adds significant weight to aircraft, disrupting balance and airflow.
Airframe icing occurs below zero degrees Celsius with liquid water or precipitation.
Horfrost forms when water vapor sublimates on cold airframes, similar to car frost.
Rime ice forms from small supercooled water droplets, creating brittle and easily removable ice.
Clear ice forms from larger supercooled droplets, leading to a heavier and harder ice to remove.
Icing can cause weight imbalance, necessitating more lift to maintain flight.
Engine icing occurs in carburetors and intakes, reducing engine power due to restricted airflow.
Carburetor icing happens when fuel vaporization drops temperature, potentially freezing the venturi tube.
Intake icing in jet engines restricts air intake, affecting combustion and power.
Icing conditions are prevalent below 10 degrees Celsius with visible moisture.
Between 0 and -20 degrees Celsius, aircraft may encounter both rime and clear ice.
Below -20 degrees Celsius, rime ice is more likely due to a higher proportion of small supercooled droplets.
Anti-icing systems should be activated at temperatures of 10 degrees Celsius or lower in clouds.
Anti-icing can be deactivated below -40 degrees Celsius as ice adhesion becomes unlikely.
Three main types of icing are identified: frost, rime ice, and clear ice, each with distinct formation processes.
The transcript provides a comprehensive guide to understanding and managing aircraft icing.
Transcripts
ice ice baby
stop collaborate and listen
maybe that's an intro
yeah
[Music]
hi i'm grant and welcome to the ninth
class in the meteorology series all
about icing
ice adds a lot of weight to the aircraft
that we then have to lift through the
air with us it also changes the shape of
aerodynamic surfaces leading to
disruption in the airflow
previously i've done a class called
contamination in the principles of
flight series which can add a bit more
information to this video should you
need it to help build a nice picture of
why icing is such a big problem for
aircraft airframe icing can occur
whenever an aircraft flies through
liquid water at temperatures below zero
degrees celsius
or if it flies through precipitation
that falls onto a cold below zero
degrees celsius airframe and it forms
ice on contact
there are few types of airframe icing
caused by slightly different conditions
the first one is horfrost
this happens when water vapor in the air
sublimates
directly to ice on the surface of the
aircraft
this is the kind of frost you would get
on your car overnight and you have to
defrost your car in the morning
it can occur in flight when flying from
an area of cold air
which has cooled the airframe
into an area of warmer
higher humidity air
and that means that the saturation water
vapor pressure reduces near the cold
airframe
and the water vapor sublimates directly
out onto
the airframe in the form of hor frost
second type of icing is known as rhyme
ice it is formed when small
supercooled water droplets come into
contact with the airframe
the impurity of the
aircraft and the airframe
gives something for the ice crystals to
form around this ice forms almost
instantaneously on the leading edges of
the airframe and the rapid freezing
process
leads to air bubbles being trapped
within the ice structure itself and this
means that right mice is quite brittle
and easy to get rid of using
de-icing systems
this type of icing is typical within
clouds themselves
as the suspended water droplets are
still small
as they have not yet grown large enough
to fall as precipitation
also it will be common in more
stratiform clouds
because the lower levels of rising air
means that the water droplets are
smaller
clear ice is rhyme ice's older brother
it is formed when large supercooled
water droplets come into contact with
the airframe rather than small
supercooled water droplets
because the droplets are larger they
take a bit longer to freeze so when the
aircraft gives something for the ice
crust to form around
they begin to freeze but keep flowing
backwards over the length of the wing
due to the airflow
and they slowly freeze as they go
this slow freezing process means that
there are a lot fewer air pockets i mean
that clear ice is
has a much more uniform structure
and it covers a large area as it's
slowly freezing and it's working its way
back
this means that it's heavier and harder
to get rid of
and as this type of ice is formed by
large super cooled water droplets in
it's more common in clouds with higher
levels of rising air and therefore
bigger droplets such as cumuloform
clouds or cumulonimbus clouds for
example you could also encounter a
mixture of both small
and large supercooled water droplets
and when you're in one cloud and then
you would have a mixture of rhyme ice
and clear ice
so why is icing even an issue then
firstly the ice that forms on the
airframe will add weight to the aircraft
so normally an aircraft is in perfect
balance if it's flying straight and
level the weight and the left are equal
to each other
and therefore if we add a bit more
weight in the form of ice
we then don't have enough lift to
balance out
this
added weight
so we're therefore going to have to
produce more lift in order to counteract
this increase in weight
if the aircraft is already carrying up
to close of its maximum load
then it might not be able to maintain
flight
if the ice build up gets too
extreme so it just simply can't produce
the correct amount of lift for this
added weight
the second problem with icing kind of
adds to this problem
so the ice on the aerodynamic surfaces
mainly the wing
will change the shape of them it'll make
them more rough at the surface what this
means in practice is you get a reduction
in lift an increase in weight which is
not a very good combo because you want
to be increasing your lift because
you've got more weight
in terms of
engine icing there's two main forms you
get carburetor and intake icing
so in a piston engine a device called a
carburetor sucks in air to the engine
using a venturi tube
and inside the venturi fuel is added in
vapor form and this fuel vaporization
causes a drop in temperature
this sudden drop in temperature can
cause ice to form and freeze to the
walls of the venturi tube as long as the
amount of water in the air
is high enough as long as there's enough
water vapor in the air
the temperature doesn't necessarily have
to be low for this to happen as the fuel
vaporization
can cause a temperature drop of around
20 degrees so if you're at 15 degrees
celsius you drop by 20 you're obviously
below freezing at that point but it's
going to be
more
obvious and more of a problem when the
temperature is already cold
so this ice that forms in the inside of
the venturi tube restricts the amount of
air that is able to flow through it and
it will lead to an incorrect ratio of
fuel to air going to the engine normally
what happens is the mixture sent to the
engine will be too rich in fuel and the
ignition of the fuel will be worse
because it's not got enough oxygen to
burn
this will lead to less power output from
the engine
and a similar thing can happen if we go
upstream of the carburetor if you think
about the vents that are actually
allowing the air in
if they become restricted with ice
less air can flow in
and leads to problems downstream with
the mixture
and a reduction in power as well so
that's a form of intake icing and you
also get intake icing on jet engines so
jet engines have large intakes where the
airframe icing occurs
and it restricts
the hole
that the air can get
to the engine basically
and it's the same sort of thing that's
happening
on the intakes of the piston engine
you're just not allowing a big enough
space for the air to flow in and it
means that downstream in the combustion
chamber
and you've got too much fuel not enough
oxygen
unless
good burn
a less good explosion in the engine
basically and a reduction in power
because of that
so icing conditions occur
whenever we are below 10 degrees celsius
and there's visible moisture in the air
10 degrees celsius is obviously not
below freezing point but when we are
moving through the air the wind on the
aircraft can basically cool it down
significantly
and if it reaches below freezing
then air moisture can freeze onto the
surface of the aircraft or the engine
intakes
when we are below zero degrees celsius
until about minus 20 degrees celsius
then we are in the band to basically
experience
large and small super cooled water
droplets in clouds
and therefore we're going to encounter
both rhyme and clay writing
when we go slightly colder and we look
between -20 and
40
there is more chance for there to be
smaller supercooled water droplets
this is because large water droplets
whilst freezing slower and more
gradually tend to form ice at a warmer
temperature than the small water
droplets
so as it gets colder there's a larger
proportion of small supercooled water
droplets than there is large super cold
water droplets
which means we're more likely to
experience rhyme ice
when we're at temperatures below 40
degrees celsius
most of these super cold water droplets
will have frozen into solid ice
and we would consider it very unlikely
for the ice particles to stick to the
aircraft and we'd say that we are no
longer within icing conditions below 40
degrees celsius
so when we're flying around we would
switch on the anti-icing whenever we
enter cloud and the temperature is 10
degrees
or lower
up until we reach about -40 and then we
can switch the anti-icing back off
to summarize then you've got three main
types of icing you've got frost
you've got rhyme ice and you've got
clear ice
core frost is when the
water vapor in the air sublimates
directly on into ice
and on the surface of the aircraft it's
very thin very easy to get rid of it's
the kind of ice you get on your
windscreen of your car
after a cold night
rime ice is formed when small super
cooled water droplets freeze
instantaneously on the leading edges of
the airframe and because this freezing
process takes place so quickly it leads
to a lot of impurities in the ice a lot
of air bubbles air pockets and therefore
rhyme ice is quite brittle and easy to
get rid of
clear ice is formed when larger super
cooled water droplets freeze on the
surface
and the leading edges of the aircraft
and because they're larger they freeze a
bit slower and they have time to
spread out over the length of the
airframe
and it's a lot more pure in its form a
lot fewer air bubbles and therefore it's
heavier and harder to get rid of
the issues with icing mainly come from
adding weight
which then needs to be balanced out by
more lift and if you're close to your
maximum amount of
uh your maximum load if you're close to
your maximum takeoff weight or landing
weight for instance
then
you might not have enough
aerodynamic lift to counteract this
added weight
and that problem is
enhanced by the fact that the ice
forming on the wings and any aerodynamic
surfaces such as the tail or the fin
will change the shape of the surface
and that means that the air flow doesn't
flow in its predicted pattern and it
disrupts the formation of these forces
and leads to in practice a loss of lift
which you add to your increase in weight
so you're getting even smaller amount of
lift and a larger amount of weight
um which adds to the problem in terms of
enginizing you get carburetor writing or
engine intake icing
carburetor icing is formed by the fuel
injection
into the carburetor
causing a reduction in temperature it
doesn't necessarily have to be below
zero degrees for this to happen but when
it's below zero degrees is easier for
this to happen
and what happens is
the venturi tube that is being used to
suck engine suck air into the engine
becomes restricted and it means that
there's less air flowing and
with a larger proportion being fuel
that means there's less oxygen to help
with the burn and the explosion in the
pistons
so
you get less power output and the same
sort of thing is happening with engine
intake icing
so normally you've got a big disk of air
coming in when you've got icing you're
restricting
the amount of air that can flow in and
it means that there's less oxygen in the
fuel to air mixture
to burn to explode in the engine and to
create that power
so you get a reduction in power if
you've got either carburetor rising or
engine intake icing
icing conditions we would consider
anything below 10 degrees celsius with
moisture in the air
with visible moisture in the air so
basically clouds or precipitation
and when you're between 0 and -20 you're
likely to get both large and small super
cooled water droplets so you're getting
both
uh clear ice and rye mice large and
small super cooled droplets
when you're between minus 20 and minus
40 you're far more likely to get rye
mice because the clear
um
the large super cooled water droplets
have already frozen into solid particles
by the time we get to these temperatures
and you're more likely to get the small
ones and therefore more likely to get
right mice
and then when we're temperatures below
minus 40
and even the rye mice will have frozen
into solid particles
and it's very unlikely for these solid
ice particles to stick to the aircraft
and therefore you would be considered as
no longer being in icing conditions so
you'd switch your anti-icing on at 10
degrees and you could switch it back off
again if you get
colder than minus 40.
Voir Plus de Vidéos Connexes
Truckee TBM 960 Crash in Icing Conditions 30 March 2024
Making YOU the Scientist: Freezing Point Depression and Phase Changes
Icing may have contributed to airplane crash in Brazil, analysts say
Cruzamento de dados mostra que avião passou por manutenção após 'dano estrutural' | FANTÁSTICO
ATPL Meteorology - Class 4: Density.
Brazil plane crash | Former NTSB investigator weighs in on possible cause of accident
5.0 / 5 (0 votes)