initial new hire part i – basic indoctrination section 2- airman specific d. meteorology star...
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Initial New HirePart I – Basic Indoctrination
Section 2- Airman SpecificD. Meteorology
Star Marianas Air, Inc.
Complete Class Roster Cell Phones OFF 10 Minutes Break every hour 1 Hour Class
Before We Start
Meteorology and Hazardous Weather
BASIC WEATHER DEFINITIONS TEMPERATURE, PRESSURE, WINDS ATMOSPHERIC MOISTURE AND CLOUDS THUNDERSTORMS ICING WINDSHEAR
METEOROLOGYOVERVIEW
BASIC WEATHER DEFINITIONS
Surface Visibility Prevailing Visibility Tower Visibility RVR AWOS ASOS Inversion
SIGMET AIRMET CWA Weather Watch Weather Warning Sig Low Lvl Prog Sig Hi Lvl Prog
Surface Visibility: horizontal distance at which a predetermined object can be seen and recognized in ambient light (determined at usual point of observation)
Tower Visibility: surface visibility observed from tower Prevailing Visibility: surface visibility equaled or exceeded in
half or more of the horizon circle (not necessarily continuous)
DEFINITIONS
RVR (Runway Visual Range): distance at which a high intensity runway light can be seen
SFC VIS vs TWR VIS: when surface vis at usual obs point or tower is less than 4 miles, the lower of the two is used as prevailing and is reported in the visibility section of observation (higher of the two is included in “Remarks” section of observation)
DEFINITIONS
AWOS = Automated Weather Observing System Designed to transmit local weather observation directly to pilot
(computer generated) Available by voice only via radio or telephone
not available from any other source AWOS access published in Airport/Facility Directory and in
appropriate Instrument Approach Procedures See AIM for format, etc.
DEFINITIONS
ASOS = Automated Surface Observation System Primary surface weather observation system in the US.
1700 systems programmed for the US. Used for METAR and SPECI reports
Available on all weather data systems and ATIS See AIM for format and use
DEFINITIONS
Inversion = Characterized by an increase of temperature with height rather than a decrease
AWW = Severe Weather Forecast Alert a preliminary message issued to alert users that a Severe
Weather Bulletin is being issued Convective SIGMET = Issued only for thunderstorms and
related phenomena
DEFINITIONS
Convective SIGMETs issued for: Tornadoes Lines of thunderstorms Embedded thunderstorms Areas of thunderstorms of level 4 intensity or higher and
coverage is 40 percent or more of the area Wind gusts of 50kts or more and/or hail equal to or greater
than 3/4 inch
DEFINITIONS
SIGMET = Issued for the following hazardous weather Severe or extreme turbulence not associated with
thunderstorms Mountain wave or CAT
Severe icing not associated with thunderstorms Widespread duststorms, sandstorms or volcanic ash lowering
inflight visibility's to less than 3 miles Volcanic eruptions
DEFINITIONS
AIRMET = Issued for the following potentially hazardous weather Moderate Icing Moderate Turbulence Sustained surface winds of 30 knots or more Widespread ceilings and/or visibilities less than 1000/3 Extensive mountain obscurement
DEFINITIONS
CWA = Center Weather Advisory issued for the following weather conditions Supplements an existing SIGMET, Convective SIGMET, AIRMET
or FA (area forecast) When the above have not been issued but reported conditions
(PIREPS, etc.) meet SIGMET or AIRMET criteria When actual or forecast conditions do not meet SIGMET or
AIRMET criteria, but reports indicate weather will adversely affect flight ops
DEFINITIONS
WEATHER WATCH = Issued when the potential for severe weather exists
WEATHER WARNING = Issued when actual severe weather is occurring
Severe Weather Criteria Thunderstorms: Surface wind equal to or greater than 50kts
and/or 3/4 inch or larger hail Tornadoes
DEFINITIONS
SIG HIGH LEVEL PROG CHART = Prognostic (forecast) chart that covers altitude range from FL240 (400mb) to FL630 (70mb) and contains the following: Location, height and speed of jet streams (polar and subtropical) Height of tropopause Areas of
CB (thunderstorm) tops moderate or greater turbulence
Position of fronts at the surface Tropical cyclones, widespread dust/sand storms, severe squall lines
DEFINITIONS
SIG HI LVL PROG
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SIG LOW LVL PROG CHART Prognostic (forecast) chart that covers altitude range from
Sfc to FL240 (400mb) and contains the following Height of freezing level In flight icing Turbulence Low IFR (less than 500/1) IFR (500/1 to 1000/3)
DEFINITIONS
SIG LOW LVL PROG
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SUMMARY--DEFINITIONS Surface Visibility Prevailing Visibility Tower Visibility RVR AWOS ASOS Inversion
SIGMET AIRMET CWA Weather Watch Weather Warning Sig Low Lvl Prog Sig Hi Lvl Prog
TemperaturePressure
Winds
Free Air Temperature: Actual air temperature also known as: ambient air temp, environmental air temp, real
air temp Cold vs Warm Air: Relative. No set value that makes air cold
or warm Air is cold in an area if surrounding temperatures are warmer Air is warm in an area if surrounding temperatures are colder
TEMPERATURE
Temperature decreases with height through the Troposphere Varies in depth with time, latitude, season
Temperature remains constant through the Tropopause Varies in thickness with time, latitude, season
Temperature increases with height through the Stratosphere
TEMPERATURE
PRESSURE = mass of air in a column of air with its base at a given altitude and the top extending to the top of the atmosphere Pressure is always a maximum at the earth’s surface Pressure always decreases with height Pressure at any altitude is the mass of air in the column
above that altitude
PRESSURE
Station Pressure: actual atmospheric pressure observed at field elevation
Sea Level Pressure: station pressure corrected to sea level using average temperature for last 12 hours
Altimeter Setting: station pressure corrected to sea level using standard temperature lapse rate
PRESSURE
PRESSURE (MB) HEIGHT (FT MSL)
1000 400
850 5000
700 10000
500 18000
400 24000
300 30000
250 34000
200 39000
100 53000
70 63000
PRESSURE AND ALTITUDE
High vs Low Pressure: relative. No set value above or below which makes an area of pressure a high or a low An area of pressure is a low if the surrounding pressure values are higher
also referred to as a “trough” or “trof” An area of pressure is a high if the surrounding pressure values are lower
also referred to as a “ridge” Meteorological terms for low and high are “cyclone” and “anticyclone”
respectively
PRESSURE
Pressure is a function of temperature a change in temperature produces a change in pressure
Cold air moving into a low pressure at a given altitude will lower or decrease the pressure at that altitude
Warm air moving into a high pressure at a given altitude will raise the pressure at that altitude
PRESSURE
Wind is a function of pressure Orientation of pressure pattern determines direction
Counter clockwise around a low or trof in Northern Hemisphere Clockwise around a high or ridge in Northern Hemisphere
Horizontal pressure difference (gradient) determines speed greater the difference the stronger the speed
WIND
Jet: a wind speed of 50 knots or stronger at any altitude Jet Core: the area that contains the maximum wind speed at
any altitude Polar Jet: the northernmost band of maximum wind at the
tropopause Subtropical Jet: the southernmost band of maximum wind at
the tropopause
WINDWIND
Definitions, Concepts and Relationships of Temperature Pressure Wind
Knowledge of meaning and relationships is essential
SUMMARY--TEMPERATURE, PRESSURE, AND WINDS
Atmospheric Moisture and
Clouds
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Three Types of Atmospheric Moisture Solid Liquid
Ordinary Supercooled
Gas (Vapor)
ATMOSPHERIC MOISTURE
Solid Ice Crystals, Snow, Ice Pellets, Hail
Liquid Ordinary
Rain, Drizzle, Fog Super Cooled (Liquid but Temperature below freezing)
Freezing Rain, Freezing Drizzle, Ice Fog Gas (Vapor)
Relative Humidity
ATMOSPHERIC MOISTURE
Supercooled Water: in the liquid state but its actual temperature is below freezing Occurs as result of rapid temperature drop, usually the result of
pressure expansion Freezes instantly upon contact with any object or surface whose
actual temperature is at or below freezing is the source of freezing precipitation as well as aircraft icing
ATMOSPHERIC MOISTURE
Gaseous Water (Vapor) Relative Humidity (RH) one method of indicating amount of water
vapor Defined as actual amount of water vapor in the air divided by the
amount of water vapor the air can hold at a given temperature RH is a function of temperature RH changes with temperature change RH changes with water vapor change
Moist air is less dense (lighter) than dry air
ATMOSPHERIC MOISTURE
Two temperatures associated with water vapor Dew Point: the temperature to which air must be lowered
for condensation (gas to liquid) to occur Wet Bulb: the temperature to which air can be lowered by
evaporating (liquid to gas) water into the air Both used as indicators of water vapor in the air
ATMOSPHERIC MOISTURE
5 Deg C or less difference between air temp and dew point Relative humidity is high At surface: fog dew or frost may form
Risk increases as difference decreases Upper air: condensation may occur (liquid water appearing),
frost (ice) may occur Dew point can be used as estimate of early morning low
temperature
SIGNIFICANCE OF DEW POINT TEMPERATURE
Indicates what air temperature will become if evaporation is taking place If wet bulb is below freezing, ice can form even if air
temperature is above freezing Can play a significant role in aircraft ground icing Dew point temperature can be used as an approximation
of wet bulb
SIGNIFICANCE OF WET BULB TEMPERATURE
Two basic types of clouds Stratiform: smooth bases and tops, comes as a layer or
multiple layers Cumuliform: tall, billowy, not layered
Can become imbedded in stratiform clouds
CLOUDS
Form in stable air Vertical motion is relatively small in magnitude and limited in
vertical extent Size of cloud droplets are relatively small
Contain both ordinary and super-cooled water drops as well as ice crystals
Produce non-showery precipitation Drizzle, Freezing Drizzle Rain, Freezing Rain Snow, Snow Grains, Sleet, Ice Pellets
STRATIFORM CLOUDS
Form in unstable air Vertical motion can be quite strong and extensive in height Size of cloud drops can range from small to extremely large
Contain both ordinary and supercooled water as well as ice crystals and hail
Produce showery precipitation with or without lightning and thunder
Precipitation includes Rain, Snow, Hail
CUMULIFORM CLOUDS
Types of Atmospheric Moisture Dew Point and Wet Bulb Temperatures Stratiform and Cumuliform clouds
SUMMARY--ATMOSPHERIC MOISTURE AND CLOUDS
Thunderstormsand
Avoidance
Basic Types Severe Classification Characteristics of Each Type Avoidance Criteria
THUNDERSTORMSAND AVOIDANCE
TWO BASIC TYPES AIRMASS SQUALL LINE (NON-AIRMASS)
ALL THUNDERSTORMS IMPLY HAIL, SEVERE TO EXTREME TURBULENCE, SEVERE TO
EXTREME CLEAR OR MIXED ICE
THUNDERSTORMS
ANY THUNDERSTORM (AIR MASS OR SQUALL LINE) IS SEVERE IF FORECAST OR ACTUAL SURFACE WIND EQUALS OR EXCEEDS 50
KNOTS FORECAST OR ACTUAL HAIL AT SURFACE EQUALS OR EXCEEDS
3/4 INCH FORECAST OR ACTUAL TORNADO
ABOVE CONDITIONS ARE “AND/OR”
SEVERE THUNDERSTORMS
TRIGGERED BY SURFACE HEATING OR OROGRAPHIC (TERRAIN) LIFTING
USUALLY EXIST AS SINGLE CELL, SOMETIMES AS A LOOSE CLUSTER USUALLY NOT SEVERE AT SURFACE CAN PRESENT SIGNIFICANT HAZARD TO ALL AIRCRAFT IN FLIGHT
AIR MASS THUNDERSTORMS
TRIGGERED BY FRONTS OR TROUGHS (TROFS) CELLS FORM IN LINES ORIENTED PARALLEL TO FRONT OR TROUGH
LINE MOVES IN SAME DIRECTION AS FRONT OR TROUGH CELLS MOVE WITH 500MB (18000FT) WIND AT HALF THE SPEED
TOPS OF CELLS OFTEN EXTEND INTO STRATOSPHERE (OVERSHOOTING)
SQUALL LINE THUNDERSTORMS
LINES AVERAGE 150NM LONG BY 25 TO 50 NM WIDE CELLS ARE FREQUENTLY SEVERE CELLS OFTEN PRODUCE TORNADOS ALWAYS PRODUCE SIGNIFICANT INFLIGHT HAZARDS MUST ABSOLUTELY BE AVOIDED
SQUALL LINE THUNDERSTORMS
SEVERE TO EXTREME TURBULENCE IN CELLS AS WELL AS AROUND OUTSIDE
ANY THUNDERSTORM ACTS AS OBSTRUCTION TO WIND AT ANY ALTITUDE PRODUCES TURBULENCE IN AIR AROUND OUTSIDE OF STORM EXTENT OF TURBULENCE IS A FUNCTION OF WIND SPEED
THUNDERSTORM AVOIDANCE CRITERIA
WINDSPEEDS OF 50KTS OR MORE 20 TO 25 NM FROM EDGE OF CLOUD
WINDSPEEDS OF 30 TO 50 KTS 15 TO 20 NM FROM EDGE OF CLOUD
WINDSPEEDS 30 KTS OR LESS 10 TO 15 NM FROM EDGE OF CLOUD
ABOVE HOLD AT ALL ALTITUDES NEVER FLY UNDER AN “ANVIL”
THUNDERSTORM AVOIDANCE CRITERIA
OVER THE TOPS - MAINTAIN 5000FT OF CLEARANCE FOR ANY WIND SPEED UP TO 50
KTS ADD 1000FT FOR EACH 10 KTS ABOVE 50KTS
60KTS = 6000FT, 70KTS = 7000FT, ETC
THUNDERSTORM AVOIDANCE CRITERIA
Thunderstorms Types Characteristics Avoidance Criteria
SUMMARY--THUNDERSTORMS AND AVOIDANCE
Aircraft Inflight Icing
TWO CONDITIONS VISIBLE MOISTURE (SUPERCOOLED WATER)
ICE CRYSTALS WILL NOT PRODUCE ICING FREE AIR (ACTUAL) TEMPERATURE RANGE BETWEEN 0 AND
MINUS 40 DEGREES C USE “SAT” IF AVAILABLE OTHERWISE, CORRECT INDICATED TO FREE AIR
TEMPERATURE AIR TEMPERATURE OUTSIDE AIRCRAFT PRODUCES ICE
INFLIGHT ICING
HAZARDS CHANGES SHAPE OF AIRFOIL SMALL AMOUNT OF ICE CAN PRODUCE SIGNIFICANT HAZARD
TYPES OF AIRCRAFT ICE RIME CLEAR MIXED
INFLIGHT ICING
RIME ICE OPAQUE OR MILKY IN APPEARANCE ROUGH IN TEXTURE FORMED BY SMALL SUPERCOOLED WATER DROPS FOUND IN STRATIFORM CLOUDS PRIMARILY FORMS ON LEADING EDGES USUALLY LIGHT TO MODERATE IN ACCUMULATION
INFLIGHT ICING
CLEAR ICE CLEAR IN APPEARANCE TAKES SHAPE OF OBJECT/SURFACE FORMING ON FORMED BY LARGE SUPERCOOLED WATER DROPS FOUND IN CUMULIFORM CLOUDS
BASES OF PRECIPITATING STRATIFORM CLOUDS RAIN OR DRIZZLE UNDERNEATH STRATIFORM CLOUDS
(FREEZING RAIN OR FREEZING DRIZZLE)
INFLIGHT ICING
CLEAR ICE FORMS ON ALL SURFACES INCLUDING LEADING EDGES MODERATE OR GREATER IN INTENSITY
FREQUENTLY SEVERE TO EXTREME CLEAR ICE CAN ACCUMULATE RAPIDLY AND IS A MAJOR HAZARD
TO FLIGHT
INFLIGHT ICING
MIXED ICE COMBINATION OF RIME AND CLEAR OCCURING
SIMULTANEOUSLY CLEAR AND OPAQUE IN APPEARANCE ROUGH IN TEXTURE FOUND IN CUMULIFORM IMBEDED IN STRATIFORM CLOUDS
LOWER PORTION OF PRECIPITATING STRATIFORM CLOUDS
INFLIGHT ICING
MIXED ICE MODERATE OR GREATER IN ACCUMULATION
FREQUENTLY SEVERE TO EXTREME MIXED ICE CAN RAPIDLY ACCUMULATE AND IS A MAJOR FLIGHT
HAZARD
INFLIGHT ICING
ICING FORECAST PRODUCTS AREA FORECASTS (FAs) SIGMETs AIRMETs ICING FORECAST CHART (MAP) SIG LOW LEVEL PROG CHART (MAP)
INFLIGHT ICING
CONDITIONS FOR FORMATION TYPES OF INFLIGHT ICING ICING FORECAST PRODUCTS
SUMMARY--INFLIGHT ICING
Ground Icing
HAZARDS FORMATION RECOGNITION CHARACTERISTICS OF DEICING AND ANTI ICING FLUIDS HOLDOVER CHARTS AND TIMES COMMUNICATIONS PRE DEPARTURE ICING CHECK
GROUND ICING
CHANGES SHAPE OF AIRFOIL CAN SERIOUSLY DEGRADE TAKEOFF PERFORMANCE CAN SIGNIFICANTLY CHANGE STALL SPEED
AFFECTS CONTROLABILITY CHANGES CRITICAL/EFFECTIVE AOA OF MAIN WING AND
HORIZONTAL STABILIZER
GROUND ICING HAZARDS
SMALL AMOUNT OF FROZEN OR PARTLY FROZEN MATERIAL IS SIGNIFICANT HAZARD
CAN FORM IN SITUATION THAT DOES NOT OBVIOUSLY APPEAR FAVORABLE FOR FORMATION OF ICE
GROUND ICING HAZARDS
FACTORS Melting/Refreezing Precipitation Wind speed Air temperature Wet bulb temperature Dew point temperature Evaporative cooling Expansion cooling
FORMATION OF GROUND ICE
EVAPORATIVE COOLING Cooling of air and exposed surfaces to wet bulb temperature
through evaporation Aided by wind speed of 10kts or more Ice, Slush can form if wet bulb temperature is below freezing
Use dew point temperature as approximate wet bulb CREATES VERY DANGEROUS SITUATION IF AIR TEMP ABOVE
FREEZING
FORMATION OF GROUND ICE
EXPANSION COOLING Cooling of air as result of rapid pressure drop (expansion) Rapid pressure drop (expansion) occurs over top of airfoils
SLUSH OR SOFT ICE CAN FREEZE ON AIRFOIL DURING TAKEOFF
FORMATION OF GROUND ICE
CONCLUSION GROUND ICE CAN FORM WHEN AIR TEMPERATURE IS BELOW
FREEZING EVAPORATIVE COOLING CAN FORM GROUND ICE ON AIRCRAFT
WHEN AIR TEMPERATURE IS ABOVE FREEZING USE DEW POINT TEMPERATURE AS INDICATOR OF ICING
POTENTIAL
FORMATION OF GROUND ICE
CHARACTERISITCS OF DEICING - ANTI ICING FLUIDS
GROUND ICING
GLYCOL BASED Ethlyne Diethlyne Propelyne
LOWER THE FREEZING POINT OF WATER SOLUABLE IN WATER
Lower the freezing point of water Dilution by water raises freezing point of solution
DEICING - ANTI ICING FLUIDS
SAME FLUID CAN BE USED FOR BOTH: Deicing (removal of ice, frost, slush) Anti Icing (prevent formation of ice, frost, slush)
FLUIDS CAN BE: Heated
Prefered for Deicing Not Heated
Prefered for Anti Icing
DEICING - ANTI ICING FLUIDS
FLUID VISCOSITY IS SIGNIFICANT TO BEHAVIOR OF FLUID VISCOSITY IS:
Relative Thickness or Thiness of fluid HIGH VISCOSITY FLUID
Thick Holds its own shape Examples: honey, syrup, heavy oil
DEICING - ANTI ICING FLUIDS
LOW VISCOSITY FLUID Thin Will not hold its own shape Example: water, etc
VISCOSITY DETERMINES BEHAVIOR AND EFFECTIVENESS OF ANTI ICING FLUID
DEICING - ANTI ICING FLUIDS
LOW VISCOSITY (THIN) FLUID WILL Shear Off (Blow Off) as soon as any shearing force (moving
air) occurs Wind, Jet Exhaust, Taxiing, Take Off
Known as Newtonian fluid Will not be contaminant Provide a short protection time against formation of ice
DEICING - ANTI ICING FLUIDS
HIGH VISCOSITY (THICK) FLUID WILL Shear off (Blow Off) only when specific shearing force (moving
air) occurs Known as a Non -Newtonian fluid
Means the moving air must reach a certain speed before it will move fluid
Required speed is determined by actual viscosity of fluid Can be a “contaminant” Provide a longer protection time against formation of ice
DEICING - ANTI ICING FLUIDS
TWO TYPES OF ANTI ICING FLUID AVAILABLE TYPE I
Low Viscosity Thin
TYPE II High Viscosity Thick
TYPE OF FLUID DETERMINES HOLDOVER TIME
DEICING - ANTI ICING FLUIDS
HOLDOVER TIMES & CHARTSHOLDOVER TIMES & CHARTS
GROUND ICING
HOLDOVER TIME Period of time that Anti Icing fluid will be effective Determined by
Type of Fluid Fluid and Water Mix Precipitation Type and Intensity Air Temperature
BEGINS AT START OF SPRAY
HOLDOVER TIME & CHARTS
DANGEROUS SCENARIO IF: Precipitation occurring (any type) Wind speed is 10 knots or more Air temperature above freezing Dew point below Freezing
USE DEW POINT FOR TEMPERATURE VALUE ON HOLDOVER CHART Will account for evaporative cooling
HOLDOVER TIME
COMMUNICATIONS
GROUND ICING
NEED TO KNOW: Weather conditions
type & intensity of precipitation wind air temperature dew point temperature
Type of Deicing - Anti icing fluid fluid concentration
Time fluid spraying began
COMMUNICATIONS
REQUIRED TO ACCOMPLISH PRE TAKEOFF CONTAMINATION CHECK WITHIN 5 MINUTES OF DEPARTURE MAY BE DONE FROM INSIDE OR OUTSIDE AIRCRAFT
FOR PREVIOUS DANGEROUS SCENARIO RECOMMEND CHECK BE DONE OUTSIDE PHYSICALLY TOUCH SURFACES TO DETERMINE IF ICE HAS
FORMED
FINAL STEP
Factors involved Fluids and Characteristics Holdover Charts and Times Communications Requirements Pre Takeoff Contamination Check
GROUND ICING--SUMMARY
Low Level Windshear
What It Is How It Affects an Aircraft Examples Weather Conditions to Watch For Rules of Thumb
LOW LEVEL WINDSHEAR
Low Level first 2000 feet above the ground
High Level more than 2000 feet above the ground
Why the distinction force of friction
Friction affects wind in bottom 2000 feet does not affect it above 2000 feet
WHAT IS LOW LEVEL?(Meteorologically Speaking)
“Low Level Windshear” Windshear from the sfc to 2000 feet agl
“High Level Windshear” Turbulence
LOW LEVEL vs HIGH LEVEL
WINDSHEAR IS TURBULENCE NO MATTER WHERE IT OCCURS
A rapid change in the speed and or direction of the wind in a small distance either in the horizontal or vertical or both
Definition of Windshear
A rapid change in the speed and or direction of the wind in a small distance either in the horizontal or vertical or both
Definition of Windshear
HORIZONTAL Wind flow parallel to ground at any altitude and any geographic
location Simply wind direction and speed on takeoff, climb, , enroute
descent, landing
WIND COMPONENTS
VERTICAL Wind perpendicular to the ground Upward and downward motion Occurs at same points as horizontal
WIND COMPONENTS
HORIZONTAL Only one significant 80 to 85% of time Vertical too small to affect aircraft (100 fpm is lowest
value) Specific weather events that produce only horizontal
shear
HORIZONTAL/VERTICAL
VERTICAL Strong as 13,000fpm or more Average is 2500 - 3000fpm 100 to 500fpm to cause problem Specific wx events that produce only vertical shear
HORIZONTAL/VERTICAL
When Significant Vertical Motion Present, Significant Horizontal Is Also Present
TWO FOR THE PRICE OF ONE
HORIZONTAL Only One Significant 80 to 85% of Time
VERTICAL Significant Only 15 to 20% of Time Produces Significant Horizontal
COMBINED Both Horizontal and Vertical
SUMMARY-- WIND COMPONENT
A rapid change in the speed and or direction of the wind in a small distance either in the horizontal or vertical or both
DEFINITION OF WINDSHEAR
RAPID CHANGE - 15 to 120 seconds SMALL DISTANCE - hundred feet to 5nm TIME RANGE 15 TO 120 SECONDS
Means wind can change direction or speed INSTANTANEOUSLY over a time period of 15 to 120 seconds
HUNDRED FEET TO 5NM Means wind can change direction or speed INSTANTANEOUSLY at
any point or points a hundred feet apart over distance of 5nm
RAPID CHANGE/SMALL DISTANCE
WINDSHEAR AFFECTS AN AIRCRAFT’S LIFT BECAUSE THE WIND CHANGES THE LIFT FASTER THAN THE AIRCRAFT’S MASS CAN BE ACCELERATED OR DECELERATED TO COMPENSATE FOR THE CHANGE
EFFECTS ON AIRCRAFT
INSTANTANEOUS CHANGES IN WIND SPEED OR DIRECTION PRODUCE INSTANTANEOUS CHANGES IN AIRSPEED AND LIFT
REACTION TO CHANGE TAKES 12 TO 15 SECONDS AND INCLUDES: PILOT’S REACTION ( 2.5 TO 3.8 SECONDS) AIRCRAFTS RESPONSE TIME TO COMMANDS
--VARIES CONSIDERABLY BY TYPE
HOW IT DOES IT!
PRIMARY CULPRIT HORIZONTAL WIND COMPONENT
ASSISTANT OR CONFUSER VERTICAL WIND COMPONENT CAN DO IT BY ITSELF!!
MOST DANGEROUS CASE SIMULTANEOUS HORIZONTAL & VERTICAL
LOW LEVEL WINDSHEAR
FROM ONE POINT TO ANOTHER AT A CONSTANT ALTITUDE
ON A DESCENT OR CLIMB
CHANGE IN HORIZONTAL COMPONENT
COMBINED WIND CONVECTIVE WX
SHOWERS RAIN, SNOW, VIRGA
THUNDERSHOWERS RAIN, SNOW, VIRGA
MOUNTAIN WAVE ROTORS
LOW LEVEL WINDSHEAR WEATHER EVENTS
HORIZONTAL WIND FRONTS
WARM COLD
SEA BREEZES VALLEY WINDS TEMP INVERSIONS
LOW LEVEL WINDSHEAR WEATHER EVENTS
CONVECTIVE WEATHER PRESENCE OF CB’s OR TCU’s VIRGA PRECIPITATION SHAFT BLOWING DUST BENDING TREES GUSTY SURFACE WINDS
THINGS TO WATCH FOR!
MOUNTAIN WAVE COPIOUS HIGH ALTITUDE TURBULENCE ON LEE SIDE ROTOR CLOUD REMARKS IN METAR STANDING LENTICULAR CLOUD REMARKS IN METAR
BLOWING DUST ERRATIC GUSTY SURFACE WINDS (no apparent cause) LARGE TEMP - DEW POINT DIFFERENCE
THINGS TO WATCH FOR!
FRONTS WARM FRONT
AIRPORT WITHIN 125NM ON COOL SIDE OF BOUNDARY COLD FRONT
AIRPORT WITH 15NM ON COOL SIDE OF BOUNDARY
THINGS TO WATCH FOR!
TEMPERATURE INVERSION CALM SURFACE WIND COOL, EARLY MORNING TEMPERATURES CLEAR SKIES (OVERNIGHT OR EARLY MORNING)
SEA BREEZE CU ALONG COAST INDICATIONS OF ONSHORE FLOW
VALLEY WINDS GUSTY SURFACE WINDS BLOWING DUST
THINGS TO WATCH FOR!
THE AIRCRAFT IN FRONT OF YOU THAT RESPONDS WHEN ASKED, “HOW WAS THE RIDE UNDER THAT BLACK CLOUD?”
WATCH OUT FOR!
IT DOSEN’T LOOK THAT BAD! OH WELL, THAT’S ROUTINE WX FOR THIS PLACE! IT’S A TYPICAL COLORADO WINDY DAY! DOSEN’T SEEM TO BE BOTHERING ANYONE ELSE! THERE ARE ALWAYS SHOWERS AROUND THIS PLACE!
FAMOUS LAST WORDS
CONVECTIVE WEATHER DOUBLE THE GUST SPEED ADD THE FULL PREVAILING TO THE FULL GUST
EXAMPLE: 15G25 = 40 TO 50 KNOT LOSS MULTIPLY THE FULL GUST SPEED BY 100 AND LABEL IT “FPM”
EXAMPLE: 25 X 100 = 2500 FEET PER MINUTE DOWNDRAFT
YES! ROUTINE SHOWERS ARE KILLERS!!!
RULES OF THUMB
NON CONVECTIVE WEATHER DIFFERENCE BETWEEN NAV EQUIPMENT WIND AT 1000 FEET
AND SFC WIND DIRECTION AND SPEED WILL OCCUR WITHIN 50 TO 100 FEET ABOVE HEIGHT OF
AVERAGE OBSTRUCTION AROUND AIRPORT WILL OCCUR AT BASE OF REPORTED CEILING IN FRONTAL CASES WILL OCCUR BY 200 TO 300 FT AGL IN OTHERS
RULES OF THUMB
GUSTY SURFACE WINDS (NON CONVECTIVE) DETERMINE THE DIFFERENCE BETWEEN PREVAILING SPEED
AND THE “FULL” GUST EXAMPLE: 13G30 = 17KT POTENTIAL LOSS
RULES OF THUMB
AVOID IT!!
CONVECTIVE WX STAY OUT OF PRECIPITATION SHAFT STAY OUT OF VERTICAL SPACE FROM THE CLOUD BASE TO THE GROUND STAY 5 NM FROM EDGE OF CLOUD
HOW TO HANDLE LOW LEVEL WINDSHEAR
IN GENERAL AIRSPEED FLUCTUATION OF 5 TO 10 KNOTS
GET READY AIRSPEED FLUCTUATION OF 10 TO 15 KNOTS
GET SET AIRSPEED FLUCTUATION 15 KNOTS OR MORE
LETS GO AROUND AND EVALUATE THE SITUATION!
HOW TO HANDLE LOW LEVEL WINDSHEAR
PAY ATTENTION TO THE WEATHER! DON’T GET CAUGHT! KEEP IT SAFE!
REMEMBER: YOU MAY BE ABLE TO HANDLE IT, BUT THE AIRCRAFT YOU ARE FIRMLY ATTACHED TO MAY NOT BE ABLE TO HANDLE IT!
SUMMMARY--WINDSHEAR
Oral, written examination not required
Examination
Student Fill-out Student Feedback Form Sign Training Record (if applicable)
Instructor Sign Class Roster Fill-out Instructor Feedback Form Sign Training Record (if applicable)
Completion of Paperwork