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Weather 1 - Focus on Microbursts
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Weather 1 - Focus on Microbursts

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Weather 1 - Focus on Microbursts Weather 1 - Focus on Microbursts Presentation Transcript

  • Welcome Kevin McNulty, Aerospace Education Officer • Introduction • Module presentation approach • Program ideas • Feedback needed • Cadet experience and interests • Raise hands for unfamiliar terms
  • 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!
  • Welcome Module 3: The Air Environment Everyone always talks about the weather, but no one ever does anything about it.
  • 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)
  • 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
  • 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
  • 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
  • Basics Air, and why you need it
  • Basics The Atmosphere
  • 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
  • Chapter one Air Circulation Radiation • 51% of sun’s radiation absorbed by Earth • Absorbed unevenly by land/water
  • Chapter one Air Circulation Convection • Warm air has lower pressure, weighs less, rises • Key cause of weather
  • Chapter one Air Circulation Revolution • Steep angle sun heats surface more than shallow angle • Summer in one hemisphere, winter in the other
  • Chapter one Air Circulation Rotation • Earth spins as air moves, deflecting longitudinal movement: The Coriolis Effect
  • 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.
  • 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
  • Focus on Microbursts A microburst is a type of windshear which is… … a very localized column of sinking air … typically associated with thunderstorms
  • Microburst Source
  • Microburst Effect on Flight A microburst can critically affect takeoff or landing
  • 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.
  • 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).
  • 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!”
  • 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.
  • First Impact: Microburst Delta 6300’ North Flight 191, August 2, 1985 Second Impact: H 114 wy Final Impact: W T ater anks 17L
  • Microburst Delta Flight 191, August 2, 1985 Compurer re-creation of microburst based on recorded NWS radar information
  • Microburst Delta Flight 191, August 2, 1985 Computer simulation based on flight recorder data Computer re-creation of crash
  • 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