The Effects of Weather
on Aircraft
Part 2 of 2
Video
Delta Flight 191
Aug 2, 1985
Causes and Effects
https://www.youtube.com/watch?v=BWtlCirzRjs
Microburst
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Is a violent downdraft
Takes place in space of less than one mile horizontally
and within 1,000 feet vertically
Lasts about 15 minutes, and can create wind speeds
greater than 115 mph
Effects of a Microburst
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Plane experiences a quick series of events
 Increased
headwinds => increased relative wind, more lift
 Downdrafts => Sudden loss of altitude
 Wind rapidly shears to tailwind => decreased relative wind,
loss of lift
 Impact with ground or aircraft pushed dangerously close to the
ground
Detecting Microbursts
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Difficult because they crop up in relatively small areas
Often associated with convective precipitation in
cumulonimbus formations
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Weather resulting from vertical exchange of heat and moisture
Airports have installed low-level wind shear alert system
NASA, FAA and others
developed sensor that reads
speed and direction of
invisible particles of water
vapor and dust in the wind
Most airliners today equipped
with these systems
Activity 2: Effects
of a Microburst
 Examine
 Answer
the illustration
the questions and explain what is
occurring with the aircraft and the
weather
Activity 3
Video
Delta Flight 191
Aug 2, 1985
Causes and Effects
https://www.youtube.com/watch?v=BWtlCirzRjs
Sandstorms
https://www.youtube.com/watch?v=ersxqFwDkWA
Sandstorms
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Strong, dry winds generally take place over arid—hot
and dry—lands
Reduce visibility, clog aircraft engines and instruments,
and make it difficult to breathe
Can damage aircraft and other machinery
Operation Eagle Claw
Runs Into Sandstorms
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November 4, 1979 – Iran Hostage Crisis
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52 American diplomats and citizens held captive 444 days
April 24, 1980, President Carter approves 2-day
rescue mission dubbed Operation Eagle Claw
 Eight RH-53D helicopters took off from USS Nimitz
and USS Coral Sea
 Helicopters would meet up with several C-130
refueling planes at area designated “Desert One”
 The aircraft ran into two major sandstorms
Operation Eagle Claw (cont)
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Prior to the sandstorms, one helicopter aborted due to
damaged rotor blade (RH-53D left in the desert)
The remaining helicopters had to spread out to avoid running
into one another during the sandstorms
A second RH-53D aborted in the second sandstorm and
returned home
A third RH-53D had hydraulic problems but made it to the
refueling location
Col Beckwith recommended aborting the mission since they
were essentially down to 5 operational helicopters
As the helicopters repositioned themselves to refuel, one ran
into a C-130 and crashed, killing 8 U.S. servicemen
How Wake Turbulence
Affects Air Flight
Aircraft generate wake turbulence while in flight
 Disturbance caused by a pair of vortices trailing
from an aircraft’s wingtips
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Dangerous to other aircraft that get too close
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Can damage aircraft parts and equipment
Intensity
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Depends on weight, speed, and wing shape of
vortex-producing aircraft
Greatest when generating aircraft is heavy, slow, and
clean
Strong vortices
created during
takeoff, climb, and
landing when angle
of attack is highest
Vortices typically last
about 3 minutes
Vortex Behavior
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Trailing vortices behave in predictable ways
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Helps pilots avoid wake turbulence
Vortices move outward, upward, and around the wingtips
Vortices generally maintain a distance of a little less than a
wingspan apart
Avoiding Wake Turbulence
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Avoid flying through another aircraft’s flight path
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The pilot should climb above the other aircraft’s climb path
until clear of its wake => rotate before previous aircraft
When landing behind a departing aircraft, land before the
departing aircraft’s rotating point
Wake Turbulence Rules
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General Rules:
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Avoid flying through another aircraft’s flight path
Avoid flying below or behind another aircraft
Maintain at least 1,000 feet of difference in altitude between
aircraft on similar flight paths
During Takeoff:
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Pilot should rotate aircraft (lift nose wheel off the runway)
before reaching point on runway at which plane ahead rotated
Wake Turbulence Rules
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During Landing:
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Approach runway above the previous aircraft’s path when
landing behind it
Touch down after the point at which other aircraft did
When landing behind departing aircraft, land before the
departing aircraft’s rotating point
Next….
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Done – the effects of weather on
aircraft
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Next – Chapter 2 Test
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Last - Human Flight Physiology