ATSC Flying Module L/O Notes PDF

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Summary

Learning Outcome 1A- Cloud Identification● Convective and Cumuliform Clouds ○ Looks like stacks of cotton balls, associated with updrafts ○ How do they form? ■ When warm, humid air rises through cooler surrounding air in atmosphere ■ Behind​ cold fronts​ (warm air mass is forced upwards by collision...

Description

Learning Outcome 1A- Cloud Identification ●

Convective and Cumuliform Clouds ○ Looks like stacks of cotton balls, associated with updrafts ○ How do they form? ■ When warm, humid air rises through cooler surrounding air in atmosphere ■ Behind cold fronts (warm air mass is forced upwards by collision with cold-air mass) ■ On mostly clear days where sun warms ground more than overlying air ■ Over urban and industrial centers that are warmer than the surrounding rural areas ■ When cold air blows over a warmer ocean or lake, or over warmer land ■ The buoyancy (tendency of objects to sink or rise due to density differences with their surroundings) associated with warm air drives strong updrafts ● More buoyancy created as water vapor in air condnses to become cloud droplets, because condensation releases latent heat (energy required during a phase change- in this case, condensation) ○ Convective clouds often have relatively flat bases that are somewhat near to the ground (~1km above ground, varies significantly from cloud to cloud) ○ Vertical depth of clouds vary significantly; comes in 4 sizes ■ Small: Cumulus Humilis (Cu hum, “fair weather cumulus”)

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Medium: Cumulus Mediocris (Cu med)

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Large: Cumulus Congestus (Cu cong, “towering cumulus (TCu)”)

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Extra Large: Cumulonimbus (Cb, thunderstorms) 

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For all size cumulus clouds, there is updraft that starts near ground level and extends up into cloud all the way to cloud time Between updrafts are weaker downdrafts of clear air Airplane and helicopters flying at constant altitude below cloud base would feel bumpy ride as they fly through up and down drafts Cat’s Paws- At earth’s surface, downdrafts of air hitting ground cause wind gusts that sailors can see as rougher, darker-looking patches of wate. Hazards ○ Deeper cumuliform clouds have stronger updrafts ■ Thunderstorms and congestus have such violent updrafts, can be hazard ○ Strong updrafts cause pilot to lose control of aircraft, over-stress aircraft ○ Medium and smaller cumulus can be flown under and through, but will be bumpy ride (need shoulder harness, barf bags, fastened seat belt) Layer Clouds or Stratiform Clouds (St) ○ look like sheets or blankets that can extend hundreds of kms horizontally (100-1000km), only 100m to 6km thick in vertical ○ Associated with layers in atmosphere with different relative temperatures ○ When horizontal wind moves warmer air towards cold wedge, warm air slides up along top surface of cold air, because warm air is more buoyant (lighter) than cold air, typical behaviour of warm fronts ■ As warm air rises, gradually cools to point where water vapor condenses and make clouds

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3 categories, classified by altitude ■ High: Cirrus (ci), cirrostratus (Cs) and cirrocumulus (Cc)

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Middle: Altostratus (As) and altocumulus (Ac)

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Low: Stratus (St) and nimbostratus (Ns)

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Nimbostratus clouds are precipitating (snow, mist, drizzle, light rain) while stratus is not Nimbostratus clouds often have diffused, washed out cloud bases, stratus clouds have well defined cloud bases

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As warm front approaches you, normally see high clouds first, see them about half a day before warm front arrives Next comes mid-level clouds Finally, Low clouds along with drizzle or light rain/snow Hazards ○ Stratiform clouds not usually turbulent, flying through is often smooth ○ Inside any cloud, pilots need to be flying on instruments because they can’t see ground or landmarks ○ If stratiform clouds are cold enough (temp just below freezing), ice can form on leading edges of aircraft due to quick freezing of supercooled (below freezing) liquid water drops ○ Soarplane pilots don’t like these clouds because they shade the ground and prevent thermal updrafts from forming

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Learning Outcome 1B- Special Clouds Clouds in unstable air aloft ● Castellanus ○ Looks like small castle turrets

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■ Sometimes form out of top layer of cloud Clue that atmosphere is becoming unstable, thunderstorms possibly later in day Bumpty if you are flying in that cloud layer, but smooth air above and below it Sometimes, thin layer of cold air will form above a thin layer of warm air ■ As warm air rises and cold air sinks, mini convective clouds form in rising air if water vapour is present Small diameter clouds, compared to altitude above gground Convective circulations of these clouds don’t touch ground, and are contained within warm-cold air sandwich layer Can form as ■ High-altitude clouds (cirrus castellanus or cirrocumulus castellanus), ■ Mid-altitude clouds (altocumulus castellanus)

■ Low-altitude clouds stratocumulus castellanus) ○ For pilots ■ Avoid flying in layer of castellanus clouds, as it would be turbulent ■ If in layer, climbing or descending small distance will get you out of layer ■ This cloud is of little use to sailplane pilots, sustained updrafts aren’t found in clear air below these clouds Billow (K-H Wave) Clouds

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Indicate wind shear (change of wind speed or direction) and clear air turbulence (CAT) ((moderate to strong bumps) at aircraft altitudes ■ Wind shear causes waves to form in layer or air where cooler air underlies warmer air ● These waves are called Kelvin-Helmholtz (KH) waves, don’t need mountains to form ○ Have short wavelengths and are relatively thin ○ Occur often, but rarely visible, when rising cool air is relatively humid ○ Parallel bands of clouds form in crest of each wave, look like billows of an accordion ○ Waves often break, causing cloud layer to be turbulent ■ While waves break, “Cat’s eye” swirls form ● Pilots avoid flying at this altitude, due to turbulence by wind shear Smoother air often above and below layer of billow clouds Because waves happen in large horizontal regions, often see billow clouds as high cloud layer (cirrocumulus undulatus) or as mid-cloud layer (altocumulus undulatus)

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Clouds associated with strong winds across mountains ○ Lenticular (mountain-wave) clouds■ Indicate vertical wind oscillations and possible mountain-wave turbulence. Sailplanes like the updraft portion of the waves, because they can "surf" the wave and fly very long horizontal distances ■ Commercial aircraft hate the waves because they often mean a very bumpy ride at all altitudes for the whole time while flying over the mountains. ■ Form in crests of mountain waves is air is humid ■ If winds hit mountains, air is forced to rise over mountain ■ On downwind side, air returns back down to starting altitude ● Due to inertia, overshoots further down, then overshoots up again ○ Air carried downwind while it is oscillating, so it traces path of wave ■ Air cools to point where clouds form ■ When air descends back down, air warms and cloud evaporates

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Clouds remain stationary relative to mountain while wind blows through the cloud (standing lenticular clouds) ● Can fly through sideways For the first wave, over mountain, lenticular cloud is called cap cloud, because it is like a hat or cap over mountain Pilots flying experience updrafts and then downdrafts, takes more to maintain constant flight altitude ● Waves can cause severe mountain wave turbulence from earth’s surface all the way to stratosphere

Rotor clouds ■ turbulent, ragged-looking clouds that form at low altitude under the crests of mountain waves. ■ rotate about a horizontal axis parallel to the mountain range. ■ Indicate severe or extreme turbulence at low altitudes due to mountain waves ■ The rotors can break off aircraft wings and cause pilots to lose control of their aircraft during take-off and landing ■ Can also affect sailors if the rotors occur over water (lakes or coastal regions) downwind of mountains. ■ If the air is relatively dry, then neither lenticular clouds nor rotor clouds will form, even though dangerous mountain waves and rotors can still be present. ● if there are strong winds blowing across the mountains, then there can be dangerous mountain waves and rotors even if you cannot see any rotor or lenticular clouds.

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Banner Clouds ■ Form on downwind side of mountain peak ■ Indicate strong turbulence touching the downwind side of a tall, isolated mountain peak.

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Clouds formed by extra heat, updrafts, turbulence ○ Pyrocumulus (cumulus flammagenius) ■ Form over forest fires and volcanoes ■ Indicate a forest fire so strong that the heat and moisture released can make a thunderstorm in the smoke.

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Pileus ■ Form over fast-growing cumulus clouds. Interesting to watch, but they are harmless, and don't affect flying, sailing or snow sports.

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fractus/scud ■ Form in turbulent humid air near the ground. ■ These scud clouds indicate high humidity (such as due to drizzle falling from higher clouds) and strong winds at low altitude. ■ Can form in 2 ways

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When warm rain falls from slightly higher clouds through cooler cloud-free air below ○ Some water evaporates from raindrops as they fall, but cases too much humidity in colder air, forcing some water vapor to re-condense back into tiny cod droplets, making the cloud ○ If cloud touches the ground, it would be called precipitation fog If air near the ground is fairly humid but somewhat cool (so that it does not want to rise as thermals), the humid air could still be forced upward if the air is windy and turbulent. ○ Turbulence creates random gusts that include some updraft gusts that lift the humid air up to its lifting condensation level ■ the height at which lifted air parcels become

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saturated, and hence where clouds will form. Since the turbulence is lifting air with varying temperature and humidity, the resulting fractus cloud has a varying or irregular cloud base (not a flat cloud base such as for cumulus clouds).

Clouds formed by humans ○ Fumulus (cumulus homogenitus) ■ Water-droplet clouds over cooling towers, harmless

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Contrails (cirrus homogenitus) ■ Aircraft condensation trail ● Water vapor is one of the combustion products when jet fuel is burned in jet engines. When this hot water vapor (invisible) mixes with somewhat humid but non-cloudy air in the atmosphere (also invisible), the resulting mixture is a water-droplet cloud ■ Indicate turbulent wing-tip vortices behind aircraft ● Strong wake turbulence caused by aircraft in front of you that made the clouds ● Heavier, slower aircraft make more intense wake turbulence ■ Small aircraft can be flipped upside down if they accidentally fly into a wing-tip vortex. ■ Military pilots hate contrails, because they reveal the aircraft to the enemy.

Learning Outcome 1C- Cloud Coverage ● ●

The fraction of the sky (celestial dome) covered by cloud is called sky cover, cloud cover, or cloud amount. It is measured in eights (oktas) the altitude of cloud base for the lowest cloud with coverage ≥ 5 oktas (i.e. lowest broken or overcast clods) is considered the ceiling

Learning Outcome 1D- Cloud Ceiling ●

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Ceiling ○ height above ground level of lowest cloud base that is below 20,000ft (6000m) that is covering MORE than half the sky (5/ 8 or greater; broken or overcast) ○ Ceilings are reported as a height (ex. Ceiling is 500ft above ground level) Vertical visibility- poor visibilities at ground level that a ground-based weather observer can’t see whether there are clouds are not

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Ceilings are measured with: ■ Traditional ceilometers — Use a searchlight (ceiling projector) at an angle relative to vertical to shine on the cloud base. Change the angle until the illuminated spot on the cloud is directly above a detector that is a known distance from the spotlight. Then use trigonometry to calculate cloud-base height. ■ Laser ceilometers — Send up a burst of light, and measure how long it takes the light from cloud base to reflect back. ■ Ceiling balloons — Watch a red helium-filled latex balloon as it rises, record the balloon flight time until it disappears into the cloud, and then calculate the ceiling altitude based on typical rise rates of those balloons. ■ Pilot reports — Ascending planes after take-off or descending planes approaching to land can report their altitude when they passed through cloud base. ■ Weather-observer estimates — These are the worst estimates, because it is difficult to judge distance by eye, UNLESS the estimates are from tall towers or mountain tops that stick up into the clouds. CAVOK = Ceiling and Visibility are OK (i.e. good for VFR flight)

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Rain ○

From variety of microscopic solid substances in atmosphere Dust storm- particles in soii lifted by turbulent winds heavy snow has visibility less than 0.4 km (0.25 miles) moderate snow has visibility in the range 0.4 to 0.8 km (0.25 - 0.5 miles). A blizzard is when there is blowing snow in the air with reduced visibility (less than or equal to 0.25 miles in USA, or 1 km in Canada) AND fast wind speeds (greater than or equal to 35 miles/hour in USA, or 40 km/hour in Canada). In extreme conditions, visibility can be so poor that pilots and observers report a "white out", where you cannot discriminate between the ground and sky because everything is white and visibility is low. Normally patchy, pilots can often fly around heavy rain regions

Learning Outcome 2A- Pressure and Density Standard atmosphere- average variation of air pressure (P), temperature (T), and density (p) with altitude ●

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Pressure ○ Measured with barometer ○ Indicates amount of force that air is pushing against each square meter of an object ○ Greater pressure implies greater force Density ○ Amount of mass of air in each cubic meter of volume

Learning Goal 2b- Altitude and Pilot Physiology ● ● ●

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Physiology- how your body, and body parts work About 4km (13,000ft) altitude above sea level, air is so thin humans start to become goofy/hypoxic (suffering from insufficient supply of oxygen) Symptoms ○ Between 12,000 and 15,000 feet: ■ Impared/reduced: judgement, memory, alertness, coordination, and ability to make calculations. ■ Headache, drowsiness, dizziness, euporia (happy, carefree), or belligerence (want to start a fight) ○ Above 15,000 ■ Periphery vision fails (becomes grayed out), leaving you with tunnel vision. ■ Your lips and fingernails become blue (called cyanosis) ■ Eventually unconsciousness and then death. Flights above 13,000ft ○ Wear oxygen mask to breathe Flights above 40,000ft ○ Use mask with pressurized supply of oxygen Flight above 62,000ft ○ Bodily fluids begin to boil ○ Altitude called armstrong altitude or armstrong limit ○ Wear a pressure suit/space suit to prevent you from boiling over

Learning Outcome 2C- Air Density and Density Altitude ● When the air is thinner (less dense), then aircraft have reduced ability to take-off and to climb (gain altitude). In general, thinner air is found at higher altitudes, so we anticipate that aircraft climb-performance would be reduced at high altitudes.

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performance similar to what the aircraft would normally find at higher altitudes. Namely, hot low-altitude air can seem like a higher altitude for aircraft flying through it. This "seems like" altitude is called the "density altitude". If the air is hot enough, the air might be so thin that aircraft cannot take off. Or even if you can take off, you might not be able to climb to a high enough altitude to get over tree-tops or mountain ridgetops. Density ○ Air density is the mass (kg) of air molecules within a volume ○ Density = mass/volume Airplanes need a certain air density in order to fly ○ Lower air density means fewer air molecules that the aircraft encounters ■ At lower density there is less air flowing over the wings, so the wings get less lift. There are fewer oxygen molecules getting into the engine to burn with the fuel, so the engine makes less power ○ As a result, decreasing air density will decrease the climb-performance of the aircraft. Namely, if the density is lower, then the aircraft will need a longer runway to take-off, and once it takes-off, it will climb (gain altitude) more slowly ○ For any given actual temperature and pressure altitude (the altitude estimated from atmospheric pressure alone), if these weather conditions are non-standard, then the aircraft behaves as if it were flying at a different altitude in a standard atmosphere. This altitude that the aircraft "feels" is called the density altitude. Summary ○ Lower pressure, higher altitude, and warmer temperatures cause a higher "density altitude". ■ Higher density altitudes indicate poorer aircraft performance. ● Poorer performance means you need longer runway to take off, your aircraft will climb more slowly, you can carry less weight such as fuel or payload, you cannot climb to as high an altitude (called the service ceiling), and you need a longer runway to land. ● If density altitude is too high, then you might not be able to take off safely

Learning Outcome 2D- Crosswinds vs. Headwinds ● ● ●

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Winds are RELATIVE to the direction you are facing relative to ground track or course Wind directly in your face that slows you down is called a headwind ○ Good during takeoff and landing, use shorter runway Wind from directly behind you is called tailwind ○ Tailwinds are often good, can go faster ○ For aircraft on airport runway, tailwinds are bad because aircraft needs more runway to take off and to land Wind from the side is called crosswind ○ Easy to compensate for by “Crabbing” (slightly flying sideways relative to track) ○ During take off and landings, crosswinds are difficult

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first plot a point on the graph corresponding to the actual (total) wind speed and direction RELATIVE TO THE DIRECTION YOU ARE FACING ○ use that point to read off the corresponding crosswind and headwind components. ■ HINT: You should conceptually rotate this whole chart until its vertical axis (the one labeled "headwind") is aligned in the direction that the aircraft is pointing. pilots try to land and take off on a runway that has a number closest to the wind direction number (rounded to nearest 10 degrees) because that gives the best headwind

Learning Outcome 2E- Wind Shear ●

Wind shear ○ Change of wind speed and/or wind direction with altitude ○ Almost always present near ground and is stronger when near-surface wind speeds are faster ○ Caused by weather systems ■ Synoptic Scale Wind Shear ● Low pressure centers, fronts, and strong surface winds ● Convective shear by thunderstorm outbursts ○ Caused wind flowing across mountains ■ Mountain-wave shear downwind of mountains ■ Channeling of winds through valleys and mountain passes (gap winds) ■ Mountain downslope, windstorms, chinooks, boras ○ Caused by turbulence behind obstacles, other large aircraft and helicopters ○ Caused by sea breeze during day near coast lines, land breeze at night, anabatic winds (warm air moving up along mountain slopes that are warmed by the sun during daytime), katabatic winds (cold air draining down mountain slopes into valleys at nighttime as the mountain slopes cool).

Learning Outcome 2F- Updrafts for Soaring ●

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Soaring ○ gliders/sailplanes need to be towed by another aircraft to good starting altitude ○ Once airborne, need atmospheric updrafts to stay aloft When wind moves air of correct static stability over mountain range, the air t...