lecture 7-flight environments
TRANSCRIPT
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AVIATION HISTORY
Lecture 7: FlightEnvironments
By: Zuliana Ismail,2010
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Earth's atmosphere
The Earth's atmosphere is a thin layer of gases thatsurrounds the Earth.
What are the Importance of Atmosphere??
Source of oxygen and carbon dioxide.Maintains the temperature and climate that sustain life on
earth.
Protection for the human on the Earth from the harmful cosmic
ray, solar radiation and ultraviolet (UV) ray.
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IONOSPHERE
Atmosphere LayersThe Earths atmosphere is divided into 5 layers-troposphere is
where all weather changes take place, the stratosphere iswhere aircraft fly and has ozone layer, then the mesosphere,
ionosphere and finally the thermosphere, which is the topmost
layer
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Troposphere
The troposphere is the lowest layer of Earth's
atmosphere.
The troposphere starts at Earth's surface andgoes up to a height of 11 km above sea level.
Between 0-36000 feet.
Almost all weather occurs within this layer
(below 15000 feet).
Air pressure and the density of the air are
also less at high altitudes.
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Stratosphere
The stratosphere is the second layer of
Earth's atmosphere.
The stratosphere occurring between about 11
km to 50km or (36000 feet-160000 feet) Ozone is primarily found in this layer (Ozone
layer). It is important to protect living earth
from the harmful effects of the sun's
ultraviolet (UV) radiation. Without the ozone layer life could not exist on
the Earth's surface.
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Mesosphere
The mesosphere is the third layer of Earth'satmosphere.
It starts about 50 km above the ground and
goes all the way up to 80 km high.
Ionosphere
Ionosphere is the layer of ionized gasses. It
can be a conductor. Ionosphere layer can act as reflector of radio
waves.
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Thermosphere
The last atmospheric layer has an altitude
greater than 80 kilometers and is called the
thermosphere.
The space shuttle orbits in the thermosphere of
the Earth.
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Weather & Aviation
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Weather & Aviation
Weather has large influences over our
lives and we have absolutely no control
over. Most of the weather that occurs on our
planet happens below 15,000 feet.
Weather is the utmost consideration of all
pilots when planning a flight.
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Aviation is Weather Sensitive
Thunderstorms
Turbulence
Aircraft Icing
Wind Shear
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Thunderstorms
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Thunderstorms
Thunderstorms is a violent storm of
thunderand lightning.
Thunderstorms are usually accompanied byhailstone , strong winds, and heavy rain.
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Hazards Of Flying In Thunderstorms
1. Lightning
Lightning is the natural high-voltage electrical
discharge between a cloud and the ground. Lightning affect the aircraft by build up the
static electricity in the airframe.
Thus, could lead to the loss of radio
communications , damage the aircraftsstructure, making instrument readingimpossible and affect the crew's vision
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Hazards Of Flying In
Thunderstorms2. Hailstone
Hailstone is a small pellet of ice which falls from
clouds.
Can cause serious damage to an airplane.
3. Strong wind
Can cause the aircraft crash during take-off or
landing.4. Heavy Rain
Can reduce the visibility, produce the visualillusion, affect the braking action needed for
landing.
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Turbulence
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Turbulence
Turbulence is caused by rapid, irregular
motion of the air.
In severe turbulence, shortly throw anairplane out of control and can cause
structural damage.
Also known as air pocket Air pocket: a small area where the air is less
dense or where there is a downward air current,
and which makes an aircraft lose height suddenly.
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How to avoid thunderstorm and
turbulence? Get weather reports before and during
flights
Weather radar displays will show areas ofturbulence to note or to avoid.
Don't fly under a thunderstorm even if you
can see through to the other side.
Avoid by at least 20 miles anythunderstorm identified as dangerous
Don't land or take offin the face of an
approaching thunderstorm.
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Aircraft Icing
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Aircraft Icing
Icing is the accumulation of ice on theexposed surfaces of aircraft.
Icing occur above the freezing level where
the water droplets are super cooled. Pilots and controllers need to be aware of
the icing process.
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Effect of the icing
1. Can reduce the aircraft efficiency.
Aircrafts efficiency reduce because lift
decrease, thrust decrease while weight and
drag increases.
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Effect of the icing
2. Can make aircraft loss of control Ice forming on the rudder, elevator aileron, brakes &
landing gear could make aircraft loss of control
3. Can affect the aircraft engine performance.
Ice forming on the engines inlet prevents the airintake & could affect the aircraft engine performance.
4. Cause an aircraft loss of radio communications.
Ice forming on the radio antenna will cause an
aircraft loss of radio communications.5. Can lead to false indications giving by flight
instruments. (Ice forming on Pitot-Static System)
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How to avoid icing
Contact the weather office to obtain a
forecast about expected icing.
Avoid flight into an area where icingconditions are known to exist. (Example:
wet snow when the temperature is near
0C).
Change altitude to get out of the icing as
rapidly as possible.
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Protection from Icing
De-icing: To remove ice after it has formed
Anti-icing: To prevent ice from forming.
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De-icing
De-icing is the process of removing snow
& ice from an aircraft surface.
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Anti-icing
Electrical systems for keeping criticalareas free of ice.
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Anti-icing
The process of spraying a glycol solution
on the parts of an aircraft to prevent the
formation of ice during inclement weatherconditions
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Wind Shear
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Wind shear
Wind shear is a quick change in the wind
speed & direction that can cause aircraft
lose in control. If an aircraft experiences a sudden
decrease in wind speed, it can reduce the
lift on its wings to dangerously low values.
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How to avoid wind shear
Aircraft must be equipped with radar/
sensors that can alert pilots to wind-shear
hazards. Many airports now have wind shear
detection equipment near the ends of
runways to warn aircraft if it is too
dangerous to land.
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VIDEO = "Cruel Skies"
This special video looked at the role of
bad weather in disasters, and toured the
US Aviation Weather Centre in KansasCity, Missouri to see how information on
weather is transmitted to pilots in the sky.
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Why do Airplanes Fly at High Altitudes?
Depending upon the length of the flight andthe type of aircraft, cruising altitudes typicallyvary between approximately 25,000 feet and
40,000 feet (FL 250-400). This altitude allows the aircraft To:
Avoid bad weather
Increase engine efficiency and save fuel
Avoid obstacles/mountains
Have clear Visibility
Avoid collision with another aircraft
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Flying High
1. To avoid bad weather
Most of the weather that occurs on our planet
happens below 15,000 feet.
There are generally fewer clouds and lessturbulence at high altitudes.
Beside that, the air is thinner at high altitude. So,
there is also less ice accumulation at high
altitudes. Thus, flying high is safer region from bad weather.
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Flying High
2. To increase engine efficiency and save fuel
The higher the aircraft altitude the thinner the
air.
As the air becomes thinner, it creates lessresistance to objects flying through it.
Therefore, less thrust is needed to move the
aircraft forward at a given speed.
As a result, airplanes can fly more efficiently at
higher altitudes with less fuel.
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Flying High
3. To avoid obstacles/mountains
Himalayan mountain includes over 100
mountains exceeding 7,200 m (23,622 ft). Aircraft flying high in order to avoid the
collision with the high mountain.
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FlyingHigh
4. To have clear Visibility
The higher the altitude the smoother the air, thus
the visibility is always better. Flying low makes aircraft too close to the clouds.
This may make it hard for the pilot to see.
Flying low means more bug and insects on the
wind shield which again can make it hard for thepilot to see in front and reduce visibility.
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Flying High
4. To avoid collisions with another aircraft
The high altitudes are also great for
separation of flights to avoid collisions. At high altitudes (above 29,000 feet) planes
are required to have at least 2000 ft of
vertical separation (it is usually 1000 ft when
below 29,000 ft).