CHAPTER 12 CHAPTER 12 COMMON IFR PRODUCERSCOMMON IFR PRODUCERS

St. Elmo’s FireSt. Elmo’s Fire

AOPA VFR into IMCAOPA VFR into IMC

http://flash.aopa.org/asf/acs_vfrimc/

Scud runningScud running

http://www.youtube.com/watch?v=0gWEi_TNKoI

IFR PROCEDURESIFR PROCEDURES

Low ceilings and non-instrument rated pilots don’t mix.

Attempting to fly visually under low cloud decks can be tricky.

Entering clouds or losing the horizon can cause your senses to deceive even the most experience instrument pilot; causing you to lose your sense of direction and lose control

IFR PROCEDURESIFR PROCEDURES

Usually it takes a good scare to really appreciate the illusions of IFR flight before you change your thinking on IFR weather.

Calgary-Regina-Grand Forks Trip Continued VFR into adverse weather is the

cause of about 25% of all fatal general aviation accidents.

VFR/MVFR/IFRVFR/MVFR/IFR What is VFR weather? Weather better than 1000 ft Ceiling;

Visibility better than 3 S.M. What is MVFR? From 1000 ft. - 3000 ft ceiling;

Visibility 3-5 S.M. What is IFR 1000 ft ceiling or below, vis 3 S.M. or

below

CEILINGCEILING Ceiling = the maximum height

from which a pilot can maintain VFR in reference to the ground

Ceiling = as the lowest broken (5/8-7/8) or overcast layer (8/8) aloft or vertical visibility (VV) into a surface-based obstruction.

IFR PRODUCERSIFR PRODUCERS Fog, low clouds, haze, smoke,

blowing obstructions to vision, and precipitation.

Fog and low stratus restrict navigation by visual reference more often than all other weather parameters.

FOGFOG Temp/Dew Point Temp spread is 2ºC (4 ºF) and

narrowing condensation/ fog/low clouds should be expected. Your book says (5 ºF)

Water vapor must condense for fog to form. If there are no condensation nuclei present then even with 100% relative humidity, fog will not form.

Salt, dust combustion by products, smoke are all classified as condensation nuclei

FOGFOG Fog is a surface based cloud composed of

either water droplets or ice crystals. With the right conditions fog can form very

quickly (few minutes) VFR-IFR. http://www.youtube.com/watch?v=6EqQ9V1e5x

Q

Be very cautious flying when the temp/ D.P.T. spread is close and getting closer.

FOG FORMATIONFOG FORMATION

Fog or a cloud may form by: #1. cooling air to its dew point, #2. by adding moisture to the air or

condensation nuclei.

FOGFOG Radiation Fog = Fog that forms on a clear

calm night or day break when the surface of the earth is cooled by radiation until the temperature of the air near the the surface is below its initial dew point temp. Restricted to land because water surfaces cool little from nighttime radiation. Usually burns off rapidly after sunrise.

wind of 5 kts or less mix the air and deepen the fog

FOGFOG Radiation Fog =most conducive to

form on warm, moist air over low, flatland areas on clear, calm nights

ADVECTION FOGADVECTION FOG Moist air moves over colder ground or

water common along the coastal areas deepens with winds up to 15 kts

depends on the wind to exist More than 15 kts tends to lift it into

low stratus Moves in rapidly with the wind day or

night and more persistent

FOGFOG

Advection Fog = forms when moist air moves over colder ground or water. Common along coastal areas. At sea it is called sea fog.

UPSLOPE FOGUPSLOPE FOG Moist stable air cooled

adiabatically as it moves up sloping terrain

depends on wind to exist very dense and can exist at high

altitudes along the upsloping terrain

PRECIPITATION INDUCED PRECIPITATION INDUCED FOGFOG

Warm rain or drizzle falling through cool air evaporation from the precip saturates the

cool air and “poof” fog associated with warm fronts mostly may also form along cold fronts and

stationary fronts little or no wind

FRONTAL INDUCED FOGFRONTAL INDUCED FOG

Usually a result of saturation due to evaporation or precipitation

Either adding the moisture or cooling the air to saturation

ICE FOGICE FOG occurs when temp is below freezing

and the vapor sublimates directly into ice crystals

conditions are similar for formation of radiation fog

-25º F or colder so usually found in arctic region or colder winter spots

STEAM FOGSTEAM FOG Air is blown from a cold

surface over warmer water Low stratus clouds hard to predict bases scud running not advisable

FOGFOG

Fog on a METAR is used to indicate visibility of less than 5/8 of a SM

FOGFOG

HAZE AND SMOKEHAZE AND SMOKE Haze - salt or dry particles not

classified as dust or something else occurs in stable air Smoke forest fires, industrial areas Both can be bad under a temp

inversion Can cause visual illusions

HAZE AND SMOKEHAZE AND SMOKE Usually only a few thousand feet thick,

but sometimes may extend as high as 15,000 feet.

Usually have well defined tops with visibility above great.

Downward visibility from a haze layer is usually very poor, especially at a slant. Worse if faced into the sun

HAZE AND SMOKEHAZE AND SMOKE Smoke concentrations form primarily

in industrial areas when air is stable. It is most prevalent at night or early morning under a temperature inversion but can persist throughout the day.

Clears a lot slower than fog Must be dispersed by air movement.

HAZE AND SMOKEHAZE AND SMOKE Needs to be blown away or Convection which allows mixing and

spreading out of the smoke or haze to a higher altitude.

BLOWING PHENOMENABLOWING PHENOMENA

Dust, sand Precip- drizzle, rain , snow White out conditions Very common to have 0, 0

weather

BLOWING PHENOMENABLOWING PHENOMENA Can blow particles as high as

15,000 feet. Visibility is restricted at the

surface and aloft. Once dust becomes airborne

may take several hours for visibilities to improve

BLOWING PHENOMENABLOWING PHENOMENA

PRECIPITATIONPRECIPITATION

Drizzle and snow restrict visibility to a greater degree than rain.

Drizzle falls in stable air and is usually associated with fog (poor vis)

Heavy snow and rain associated with a severe thunderstorm can result in 0 vis.

With heavy rain visibilities seldom below a mile and usually for a short period of time.

PRECIPITATIONPRECIPITATION

Freezing precipitation - freezing to the windshield lowers visibility to a few inches.

OBSCURATIONOBSCURATION

surface based phenomena classified in 10ths VV ceiling may be noted but once

below it horizontal vis may be severely restricted

OBSCURATIONOBSCURATION An obscured ceiling differs from a

cloud ceiling. With a cloud ceiling you normally can see the ground and runway onced you descend below the cloud base. With an obscured ceiling, it restricts visibility between your altitude and the ground

OBSCURATIONOBSCURATION

VISIBILITYVISIBILITY

Ground level, air-to-ground and air-to-air visibilities are all important when flying.

Ground Level - done by weather observer uses a prominent object viewed against the horizon for estimating daytime visibility.

VISIBILITYVISIBILITY

Prevailing Visibility - is provided for aviation by the weather service. It is the maximum visibility common to sectors comprising one half or more of the horizon circle as viewed from the observing site at eye level. It is provided in statute miles.

RVR RUNWAY VISUAL RANGERVR RUNWAY VISUAL RANGE For landing and take-off under

instrument flight conditions, the prevailing visibility is not of as much importance as the visibility within the runway environment itself.

Requirements is that of the runway lights rather than ground feature.

Measured by an instrument called a transmissometer

RVR RUNWAY VISUAL RANGERVR RUNWAY VISUAL RANGE RVR is measured in feet in North

America. Values are measured by

transmissometer mounted on 14 foot towers along the runway 250 feet apart typically.

1,600=1/4 2,400=1/2 3,200= 5/8 5,000=1mile

RVR RUNWAY VISUAL RANGERVR RUNWAY VISUAL RANGE Air to ground visibility - prevailing and

rvr are horizontal visibilities near the surface.

Air to ground is forward visibility, typically lower then the above two

SVR slant visual range - slant visual distance used for the choice to continue to land or not.

ILLUSIONS IN FLIGHTILLUSIONS IN FLIGHT AIM 8-1-5 The leans - An abrupt correction of a banked

attitude, which has been entered too slowly to stimulate the motion sensing system in the inner ear, can create the illusion of banking in the opposite direction. The disoriented pilot will roll the aircraft back into its original dangerous attitude, or if level flight is maintained, will feel compelled to lean in the perceived vertical plane until this illusion subsides

ILLUSIONS IN FLIGHTILLUSIONS IN FLIGHT AIM 8-1-5 Coriolis illusion - An abrupt head movement in

a prolonged constant-rate turn that has ceased stimulating the motion sensing system can create the illusion of rotation or movement in an entirely different axis. The disoriented pilot will maneuver the aircraft into a dangerous attitude in an attempt to stop rotation. This most overwhelming of all illusions may be prevented by not making sudden, extreme head movements (especially while turning)

ILLUSIONS IN FLIGHTILLUSIONS IN FLIGHT False Horizon - Sloping cloud formations,

an obscured horizon, a dark scene spread with ground lights and stars, and certain geometric patterns of ground light can create illusions of not being aligned correctly with the actual horizon. The disoriented pilot will place the aircraft in a dangerous attitude

ILLUSIONS IN FLIGHTILLUSIONS IN FLIGHT Graveyard spin - A proper recover from a spin

that has ceased stimulating the motion sensing system can create the illusion of spinning in the opposite direction. The disoriented pilot will return the aircraft to the original spin.

Graveyard spiral - Constant rate turn descending can cease to stimulate your senses, so that you believe your wings are level. Pulling back on the controls tightens the spiral even more

ILLUSIONS IN FLIGHTILLUSIONS IN FLIGHT Atmospheric illusions - Rain on the

windscreen can create the illusion of greater height, and atmospheric haze the illusion of being at a greater distance fro mthe runway. The pilot who does not recognize these illusions will fly a lower approach. Penetration of fog can create the illusion of pitching up. The pilot who does not recognize this illusion will steepen the approach, often quite abruptly.

ILLUSIONS IN FLIGHTILLUSIONS IN FLIGHT

TRUST YOUR INSTRUMENT READ 8-1-5 IN YOU AIM IF

YOU GET A CHANCE

IFR IFR

If you can go IFR, get a clearance before you lose your horizon or enter clouds.

If VFR make a 180. Any pilot knows how to make a 180; a good pilot knows when!!!!!

Don’t get “get to your destination itis” Wait until the weather is good for VFR

QUESTIONSQUESTIONS

Where can you encounter wind shear?

Any altitude, can be both in the horizontal and vertical direction.

QUESTIONSQUESTIONS

When is it more likely to have radiation fog form?

Over land clear calm nights

QUESTIONSQUESTIONS

When is it more likely to have advection fog form?

Along coastal areas

QUESTIONSQUESTIONS

When is it more likely to have steam fog form?

Over a water surface

QUESTIONSQUESTIONS

What types of fog depend on wind in order to exist?

Advection fog and upslope fog

QUESTIONSQUESTIONS

In industrial areas low clouds and fog are common why?

Increase in cloud condensation nuclei.

FMH-1 CHAPTER 12FMH-1 CHAPTER 12

METAR KMWH 092052Z 22003KT 10SM SCT009 02/M02 A2981 RMK AO2 SLP105 6//// T00171022 55000 PNO $

6=3 and 6 hour precip amount ////=indeterminable amount of precip If 2.17 inches of precip occurred would be

coded 60217

METAR KMWH 092052Z 22003KT 10SM SCT009 02/M02 A2981 RMK AO2 SLP105 6//// T00171022 55000 PNO $

5=3 hour pressure tendency Next digit need to reference table 5 on the table =

atmospheric pressure now lower than 3 hours ago decreasing then increasing

000 = amount of pressure change in tens of hectopascals

52032 = steady increase of 3.2 hectopascals in the past three hours

METAR KMWH 092052Z 22003KT 10SM SCT009 02/M02 A2981 RMK AO2 SLP105 6//// T00171022 55000 PNO $

PNO = when automatic stations are equipped with a tipping bucket rain gauge and that sensor is not operating PNO shall be coded

$ = maintenance is needed on the system