The crash of Delta Flight 191 highlighted the dangers posed by microbursts and helped advance understanding and detection of these localized downdrafts. The NTSB investigation found the primary cause was pilot error in deciding to land in a thunderstorm that produced the fatal microburst. This tragic event spurred further research into microbursts and development of warning systems to help pilots avoid these hazardous wind shears.

1. Welcome
Kevin McNulty, Aerospace Education Officer
• Introduction
• Module presentation approach
• Program ideas
• Feedback needed
• Cadet experience and interests
• Raise hands for unfamiliar terms

2. Welcome
Kevin McNulty, Aerospace Education Officer
• Email: kevmcnulty@gmail.com
• Home phone: 941-729-8928
• Cell phone: 941-737-8575
• Send me email if you would like a copy of this
PowerPoint!

3. Welcome
Module 3:
The Air Environment
Everyone always talks about the weather,
but no one ever does anything about it.

4. Overview
Module Learning Objectives
Chapter 1 - Air Circulation
• Describe how the Sun heats the Earth
• Describe the Earth’s rotation and revolution and
its effect on the seasons
• Explain the various theories of circulation
• Describe Coriolis Force
• Define the jet stream
(give three examples…just kidding)

5. Overview
Module Learning Objectives
Chapter 2 - Weather Elements
• Define wind
• Describe the Beaufort Scale
• Define heat
• Explain what temperature is and how it can be
expressed
• Describe what wind chill is and what it does
• Describe how a microburst can affect a plane

6. Overview
Module Learning Objectives
Chapter 3 - Moisture and Clouds
• Describe the condensation process
• Describe how saturation occurs
• Define dew point
• Define what precipitation is and give some
examples (not kidding this time)
• Define fog
• Define turbulence

7. Overview
Module Learning Objectives
Chapter 4 - Weather Systems and Changes
• Define an air mass and their characteristics
• Define a front and describe types of fronts
• Describe hurricanes, thunderstorms, and
tornadoes
• Identify the stages of a thunderstorm
• Outline safety precautions for thunderstorms and
tornadoes

8. Basics
Air, and why you need it

9. Basics
The Atmosphere

10. Chapter one
Air Circulation
Causes of Air Circulation
• Sun heats Earth via radiation and that heat is
absorbed unevenly
• Earth rotates on its axis and revolves around the
sun.
• Uneven heating plus the Earth’s movement is the
cause of air movement and thus weather

11. Chapter one
Air Circulation
Radiation
• 51% of
sun’s
radiation
absorbed
by Earth
• Absorbed
unevenly by
land/water

12. Chapter one
Air Circulation
Convection
• Warm air
has lower
pressure,
weighs
less, rises
• Key cause
of weather

13. Chapter one
Air Circulation
Revolution
• Steep angle
sun heats
surface more
than shallow
angle
• Summer in one
hemisphere,
winter in the
other

14. Chapter one
Air Circulation
Rotation
• Earth spins
as air
moves,
deflecting
longitudinal
movement:
The
Coriolis
Effect

15. Chapter one
Air Circulation
Jet Stream
• Large temperature
differences in the
upper troposphere
cause large
pressure differences
• Result is strong
(120-150 mph) high
wind known as the
jet stream.

16. Chapter two
Weather Elements
Wind
• A body of air in motion having a direction (use
“from” direction) and speed
• Measured in knots, mph, or on Beaufort Scale
(see book)
• Wind critically affects flight
• Headwind increases lift
• Tailwind increases speed
• Differential winds cause turbulence
• Wind shear causes erratic course changes

17. Focus on
Microbursts
A microburst is a
type of windshear
which is…
… a very localized
column of sinking air
… typically
associated with
thunderstorms

18. Microburst
Source

19. Microburst
Effect on Flight
A microburst can critically affect takeoff or landing

20. Microburst
Delta Flight 191, August 2, 1985
Sequence of Events Leading up to Crash
• As L-1011 approached DFW for landing, an isolated
thunderstorm developed near the end of the runway.
• Crew noticed storm cell ahead, but decided to proceed
through it anyway, against company wx avoidance
rules; they could not know the cell was spawning a
microburst in their path.
• At about 1500 feet AGL, First Officer Price reported
seeing lightning in one of the clouds ahead.

21. Microburst
Delta Flight 191, August 2, 1985
Sequence of Events Leading up to Crash
• Unaware of microburst, DL191 entered leading edge of
vortex ring headwinds.
• At 800ft AGL, headwinds cause uncommanded pitch
and acceleration from 149kt IAS to 173kt IAS.
• Price was flying and tried to stabilize the aircraft's
speed, but CPT Conners had recognized the speed
increase as a sign of wind shear, warning Price to
watch speed and telling him to “push up” (the throttles).

22. Microburst
Delta Flight 191, August 2, 1985
Sequence of Events Leading up to Crash
• As aircraft flew through headwinds to center of vortex
ring, airspeed suddenly dropped from 173kt to 133kt,
and Price pushed the throttles forward.
• Hitting downdraft, airspeed suddenly dropped to 119kt
and sink rate increased. On the CVR Conners can be
heard saying "Hang on to the son of a bitch!” and
instructing Price to push the throttles “way up!”

23. Microburst
Delta Flight 191, August 2, 1985
Sequence of Events Leading up to Crash
• Price tried to avoid a stall by pushing the nose down.
• Nose-down attitude plus downdraft increased sink rate
to 1,700 ft/min before impact.
• The L-1011 first impacted the ground on a field about
6,300ft north of 17L and bounced back into the air.
• While crossing Hwy 114 it came down again on top of a
vehicle, killing its occupant.
• Aircraft skidded onto the airfield, collided with two 4 mil
gal water tanks at a speed of 220kt, and exploded.

24. First Impact: Microburst
Delta
6300’ North Flight 191, August 2, 1985
Second Impact:
H 114
wy
Final Impact:
W T
ater anks
17L

25. Microburst
Delta Flight 191, August 2, 1985
Compurer re-creation of microburst based on
recorded NWS radar information

26. Microburst
Delta Flight 191, August 2, 1985
Computer simulation based on flight recorder data
Computer re-creation of crash

27. Microburst
Delta Flight 191, August 2, 1985
Aftermath
• Primary cause found to be pilot error for violating
company wx avoidance rules and deciding to land
in adverse conditions
• Prior to crash, microbursts poorly understood
• Because of crash, microbursts extensively studied
and warning systems developed including ground
and aircraft radar systems