lecture 7-flight environments

8/7/2019 Lecture 7-Flight Environments

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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).

lecture 7-flight environments

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