Lesson 24 - Hazardous Weather
What are the three types of structural icings?
- Rime - Clear (or glaze) - Mixed
What are the three distinct stages a thunderstorm cell undergoes?
- Towering cumulus stage (updraft speeds > 3,000 ft/ min) - Mature stage (precipitation downdraft) - Dissipating stage (tapers off and ends)
What phenomena are included with adverse wind?
- crosswinds - gusts - tailwind - variable wind - sudden wind shift
What temperature is it too cold for icing?
-40 degrees Celsius
Low-level wind shear is a change in wind speed of ______ knots or more within ______ feet AGL.
10; 2,000
Which effect occurs to airplanes on departure during a high density altitude condition?
A longer takeoff roll is required
_______ are issued for widespread mountain obscuration.
AIRMETs
_______ is responsible for most weather-related accidents.
Adverse wind
What is referred to a "whiteout", reaches a height of 6 feet or more above the ground, and may reduce horizontal visibility to less than 7 SM?
Blowing Snow
______ is the lowest layer aloft reported as broken or overcast.
Ceiling
What is the turbulence phenomenon occurring at high altitudes (20,000 to 50,000), in cloud-free regions, associated with wind shear, between the core of a jet stream and the surrounding air.
Clear Air Turbulence (CAT)
What type of structural icing is most hazardous, in which pilots may not see it and can spread beyond the reach of the de-icing/anti-icing equipment?
Clear ice
What is glossy and clear, formed by the relatively slow freezing of large supercooled water droplets?
Clear ice (or glaze ice)
_____________ are most active on warm summer afternoons when winds are light and is indicated by billowy cumuliform clouds.
Convective currents
During what type of turbulence is the aircraft violently tossed about and practically impossible to control?
Extreme (EXTRM)
_____ is the most common and persistent weather hazard encountered in aviation.
Fog
_____ reduces horizontal visibility to less than 5/8 SM, forms when the temperature and dewpoint spread is at or near zero, and when a cloud with its base at the earth's surface.
Fog
Which airplane would be most at risk from a 25-knot crosswind on landing?
General aviation, single propeller
In general, what term is used to describe, any deposit of ice forming on an object caused by the impingement and freezing of liquid (usually super-cooled) hydrometeors?
Icing
Which adverse effect of structural icing is least significant to an aircraft?
Increased weight
What is ceiling classification that is applied when the reported ceiling value represents the vertical visibility upward into a surface-based obscuration?
Indefinite Ceiling
Which type of aircraft will perform better in adverse wind conditions, due to its higher tailwind and crosswind thresholds?
Larger airplanes
What type of turbulence momentarily causes slight erratic changes in altitude and/or attitude (pitch, roll, yaw) and occupants may feel a slight strain against seat belts but food or service may be conducted?
Light (LGT)
What wind shear is below 2,000 ft AGL, other than convectively induced, and 10 kts or more per 100 feet?
Low-level wind shear (LLWS)
What type of turbulence is caused by any obstruction to the wind, such as buildings or mountains and disrupt the smooth flow of air?
Mechanical
What structural icing is a combination of both rime and glaze ice characteristics?
Mixed ice
What type of turbulence will cause occupants to feel a definite strain against seatbelt and food/service walking are difficult. Aircraft remains in positive control but changes in altitude/ attitude occur?
Moderate (MOD)
With ______ icing the rate of accumulation is such that even short encounters become potentially hazardous and use of de-icing/anti-icing equipment is necessary.
Moderate (MOD)
What forms when stable air flow passes over a mountain or mountain barrier and extend upward into the lower stratosphere?
Mountain wave
What is any form of water particles, whether liquid or solid, that falls from the atmosphere and reaches the ground?
Precipitation
What is rough, milky, and formed by the instantaneous freezing of small supercooled water droplets after they strike the aircraft?
Rime ice
Which of the following clouds would provide visual proof that a mountain wave exists?
Rotor clouds
What type of turbulence causes occupants to be forced violently against seat belts or shoulder straps, unsecured objects to be tossed about, and makes food service and walking impossible and causes abrupt altitude/attitude changes; aircraft may be momentarily out of control?
Severe
With _____ icing the de-icing/anti-icing equipment fails to reduce or control the hazard. Immediate flight diversion is necessary.
Severe (SEV)
What ice sticks to the outside of an airplane?
Structural Icing
________ destroys the smooth flow of air, increasing drag while decreasing the ability of the airfoil to create lift.
Structural icing
What is liquid water at temperatures below the freezing point, that will crystalize in the presence of a solid; often exist in stratiform and cumulus clouds and will form on aircrafts when flying through these clouds?
Supercooled Water
What is a storm produced by a cumulonimbus cloud, and always accompanied by lightening and thunder, usually with strong gusts of wind, heavy rain, and sometimes with hail?
Thunderstorm
Which stage of a thunderstorm is characterized by updrafts exceeding 3,000 feet per minute?
Towering cumulus
With ______ ice becomes perceptible and de-icing/anti-icing equipment is not used unless encountered for an extended period of time (over 1 hour)
Trace
What is the feeling that you or your environment is moving or spinning and the most common cause of accidents from VFR pilot in IFR weather?
Vertigo
What is the single greatest cause of fatal accidents?
Visual flight into IFR weather
_________ may NOT be detected by aircraft or ATC radar.
Volcanic Ash
What generates turbulence between two wind currents of differing wind directions and/or speeds?
Wind shear
It may be impossible to recover from _______ encountered at low altitude.
a microburst
Water vapor, lift, and unstable air are necessary for the formation of ______.
a thunderstorm cell
What is the total lifecycle of a thunderstorm cell?
about 30 minutes
Most aircraft accidents related to instrument weather involve pilots who _______.
are NOT instruments rated
Light turboprop aircraft are more susceptible to icing than commercial jet aircraft because they typically fly ______.
at lower altitudes
When an airplane is taking off into a headwind, gusts may cause it to _______.
bounce on the runway
Adverse winds impact traffic by _____
change of runway configuration and reduced arrival rates
When the air is too dry for cumuliform clouds to form, _______ currents caused by uneven surface heating can still be active and cause turbulence.
convective
A wind NOT parallel to the runway or path of an aircraft is called a(n) ______.
crosswind
While an aircraft is on approach, a shear from a headwind to a tailwind causes airspeed to _____, the nose to pitch _______, and the aircraft to ______ the glideslope.
decrease; down; drop below
A ______ is a strong downdraft which induces an outburst of damaging winds on or near ground, with sizes varying from 1/2 mile to less to more than 10 miles.
downburst
An area as large as 10 miles or more of strong damaging winds reaching speeds as high as 120 knots, on or near the ground, is a _______.
downburst
Wind shear is especially dangerous when it is encountered ______
during takeoff and landing
A ______ increases airspeed, which increases lift, and may cause an aircraft to briefly rise. Likewise, once it ends, a sudden decrease of airspeed occurs, which decreases lift and causes aircraft to sink.
gust
While an aircraft is on approach, a shear from a tailwind to a headwind causes airspeed to _____, the nose to pitch _______, and the aircraft to ______ the glideslope.
increase, up, rise upward above
With ______ ice, the rate of accumulation may create a problem if flight is prolonged (over 1 hour). Occasional use of deicing/anti-icing equipment removes/ prevents accumulation.
light (LGT)
A _______ is a convective downdraft with an effected outflow area of at least 2 1/2 miles wide with peak winds of 5 and 20 minutes.
macroburst
A _______ is a small downburst with outbursts of damaging winds extending 2.5 miles or less.
microburst
Aircraft icing potential is NOT dependent upon ______.
pilot rating
A sudden wind shift, even at low speeds, can be hazardous on takeoff and landing because it can ______.
quickly become a crosswind or tailwind
A variable wind can be hazardous on takeoff and landing because it could _______.
quickly become a crosswind or tailwind
Which precipitation types most commonly produce instrument weather?
rain, drizzle, and snow
High density altitude ______ an aircraft's power and thrust.
reduces
Although _____ is most common type of icing, it is the least serious because it is easier to remove.
rime
When de-icing or anti-icing equipment fails to reduce or control the icing hazard, the icing is categorized as _____.
severe
A ______ can be hazardous during takeoff and landing due to longer takeoff roll (may roll off the end of runway), smaller initial rate of climb in takeoff (insufficient to clear obstacles), and longer landing roll (less time to make adjustments).
tailwind
A _______ is any wind more than 90 degrees to the longitudinal axis of the runway.
tailwind
The most critical periods of any flight, which are more susceptible to adverse wind are during ______.
takeoff and landing
Increased temperatures with increased altitude is known as ______.
temperature inversion
Airplane performance gradually degrades and directional control of the aircraft becomes increasingly difficult, as the wind _____.
turns perpendicular to the runway
Wind direction is considered to be _____ when, during the 2-minute evaluation period, it fluctuates by 60 degrees or more and the wind speed is more than 6 knots, and, when the speed is 6 knots or less.
variable
Severe damage can occur if _____ is ingested into an engine.
volcanic ash
Thunderstorm cell formation requires _______, unstable air, and lift.
water vapor
An aviation ______ is an atmospheric condition which, when encountered in flight, can potentially cause damage to the aircraft, personal injury, a crash, or death.
weather hazard
