Observer Scanner Training Understanding Weather Section 10 by 1st Lt. Alan Fenter.

Observer Scanner Training

Understanding WeatherSection 10

by 1st Lt. Alan Fenter

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Section 1: Reduced Visibility

Objective:Discuss acceptable flight visibility, fog, and search area hazards.

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Flight Visibility

Category Ceiling Visibility

IFR Below 1000 Feet

And /or Less than 3 miles

MVFR 1000 to 3000 Feet

And /or 3-5 miles

VFR* Greater than 3000 Feet

And Greater than 5 miles

*By definition, VFR is greater or equal to 1,000 Ft. Ceilings & greater or equal to 3 miles visibility. MVFR is a sub category of VFR

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Check for Understanding

What does the FAA consider acceptable visibility for Safe flight?

3 miles lateral visibility with 6/10 of cloud cover with a base at least

1000 feet above the surface.

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Check for Understanding

What is the biggest problem caused by fog?Difficult of impossible to see runways

or landing areas

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What type of man-made object becomes a much greater hazard to search aircraft when visibility is poor?

Very tall towers

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Section 2: Haze and Smoke

Objective:Complete statements concerning haze and smoke as flight hazards.

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Check for Understanding

A fine dust causing a lack of transparency in the air is called ________.

haze

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Check for Understanding

A condition in which cooler air is overlain by warmer air is called ____________________.

Temperature Inversion

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Check for Understanding

A stable atmosphere means the air does not mix through transfer of ________.heat

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Check for Understanding

The transfer of heat is called ____________.

Convection

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Check for Understanding

Calm winds that do not move haze and smoke out of areas cause poor ________.visibility

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Check for Understanding

In the summer smoke and haze may extend upward over _______ feet during the heat of the day.

10,000

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Check for Understanding

In smoke and haze the greatest surprise to small aircraft pilots is the ______________.

Thunderstorm

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Section 3: Blowing Dust, Snow, & Sand

Objective:Discuss the conditions and dangers involved with dust, sand, snow, and whiteout.

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Blowing Dust or Sand

Wind can spread dust over hundreds of miles and upward to 15,000 feet.One choice…Turn and LAND!

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Section 4: Turbulence

Objective:Select true statements from false ones concerning wake turbulence, its dangers, and proper procedures to deal with it.

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Four Categories of Turbulence:

Light - unsecured objects are displace slightly Moderate - unsecured objects are dislodge Severe - unsecured objects are tossed about Extreme - aircraft practically impossible to control

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Turbulence types:

Low-Level Turbulence LLT Turbulence Near Thunderstorms TNT Clear Air Turbulence CAT Mountain Wave Turbulence MWT

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Low-Level Turbulence (LLT)

Turbulence below 15,000 feet Due to surface heating or friction, within a few thousand feet of the ground LLT includes Mechanical Turbulence Convective Turbulence Frontal Turbulence and Wake

Turbulence

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Mechanical Turbulence

Obstructions such as a line of trees, buildings and hills Strong winds flowing perpendicular to mountain ridges - greatest on leeward side During gusty wind conditions, approach and land using power-on

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Convective Turbulence

Cause by thermals produced by daytime heating of the air in contact with the hot ground. Bubbles of air (thermals) rise causing low level turbulenceIf the air is moist, cumulus clouds may be seen Convective turbulence can be from light to severe turbulence

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Frontal Turbulence

Just ahead of a fast moving cold front Updrafts can reach up to 1000 feet per minute

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CAT - Clear Air Turbulence:Turbulence in clear air- no visual warnings It is usually encountered above 15,000 feet

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CAT - Clear Air Turbulence:Often develops near the jet stream (narrow band of very fast winds near the tropopause When a pilot enters an area where significant CAT has been reported, an appropriate action when the first ripple is encountered is to adjust airspeed to that recommended for rough air A curving jet stream (associated with a deep trough) produces greater turbulence than a straight jet stream

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Mountain Wave turbulence:

When wind is 40 Kts. or more across mountain tops One of the most dangerous features of mountain wave is the turbulent area in and below rotor clouds

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Wake Turbulence

A wing generating lift spills the higher pressure air (from under the wing) at the wing tip causing wingtip vortices The greatest vortex strength occurs behind heavy, clean, and slow aircraft. (After takeoff: high angle of attack and maximum gross weight) When taking off behind a large aircraft on the same runway, takeoff at a point before the takeoff point of the departing aircraft

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Wake Turbulence

When landing behind a large aircraft on the same runway, stay at or above the other aircraft's final approach flight path and land beyond that airplane's touchdown pointThe wind condition that prolongs the hazards of wake turbulence on a landing runway for the longest period of time is a light quartering tail wind

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Causes of turbulence include encountering air too close to:

Thunderstorms and cumulus cloudsAtmospheric waves produced by mountainsAir flowing around hilly terrainAtmospheric cold and warm frontsTropical storms or hurricanesEdges of jet streams

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Section 5: Icing

Objective:Discuss the effects and dangers of icing, particularly glaze and frost on an aircraft.

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Kinds of Ice

Rime IceClear or Glaze IceMixed IceFrost

10.8% of all weather

accidents result from

icing

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Close-up of leading edge ice formation

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In-flight wing leading edge ice formation

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Section 6: Severe Weather

Objective:Complete statements concerning weather threats to aircraft, particularly thunderstorms, their development, and effects.

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Cumulus Stage

Updrafts form from heating and can reach speeds of several thousand FPM.Altitudes can exceed 40,000 Feet

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Mature Stage

Marked by the beginning of rain on the ground.This cloud has become a cumulonimbus cloud because it has an updraft, a downdraft, and rain.

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Dissipating Stage

After about 30 minutes, the thunderstorm begins to dissipate. This occurs when the downdrafts in the cloud begins to dominate over the updraft.Longest stage of a Thunderstorm.