Question 1

What are the characteristics of stable air?

Accepted Answer

Stable air resists vertical motion, leading to smooth air, stratiform (flat) clouds, continuous (steady) rain, and often poor visibility due to trapped pollutants (fog/haze).

Question 2

What are the characteristics of unstable air?

Accepted Answer

Unstable air encourages vertical motion, causing turbulence, vertically developed (cumulus) clouds, showery rain, and generally good visibility (as pollutants are mixed out).

Question 3

What effect does high density altitude have on the performance of a small unmanned aircraft?

Accepted Answer

High density altitude means 'thinner' air. Propellers are less efficient, wings create less lift, and motors (even electric ones due to cooling and prop load) struggle more. Performance decreases.

Question 4

Which combination of atmospheric conditions will result in the highest density altitude?

Accepted Answer

Density altitude increases with high temperature (air expands), high altitude (less pressure), and high humidity (water vapor is lighter than dry air).

Question 5

What is the standard sea level pressure?

Accepted Answer

Standard atmospheric pressure at sea level is 29.92" Hg or 1013.2 hPa (mb).

Question 6

What causes wind?

Accepted Answer

Wind is caused by air flowing from areas of high pressure to areas of low pressure.

Question 7

In the Northern Hemisphere, how does wind flow around a Low Pressure system?

Accepted Answer

Due to the Coriolis effect, air flows counterclockwise and inward (cyclonic) around a low pressure system in the Northern Hemisphere.

Question 8

A sudden, drastic change in wind speed and/or direction over a small area is known as:

Accepted Answer

Wind shear is a sudden change in wind speed or direction over a short distance, which can occur horizontally or vertically and is hazardous to aircraft.

Question 9

Low-level wind shear is commonly associated with:

Accepted Answer

Wind shear is frequently found near thunderstorms (microbursts), passing fronts (where airmasses collide), and strong temperature inversions.

Question 10

The mature stage of a thunderstorm is characterized by:

Accepted Answer

The mature stage begins when rain falls from the cloud base. It is the most dangerous stage, featuring both strong updrafts and downdrafts.

Question 11

What type of fog forms when moist air moves over colder ground or water?

Accepted Answer

Advection fog forms when warm, moist air moves (advects) horizontally over a colder surface, cooling it to the dew point. It requires wind.

Question 12

What type of fog typically forms on clear, calm nights when the ground cools rapidly?

Accepted Answer

Radiation fog forms due to terrestrial radiation cooling the ground, which then cools the air above it. It requires calm wind and clear skies.

Question 13

The suffix 'nimbus', used in naming clouds (e.g., cumulonimbus), means:

Accepted Answer

Nimbus means 'rain'. Cumulonimbus clouds are heavy rain/thunderstorm clouds. Nimbostratus are rain-bearing layer clouds.

Question 14

Which thunderstorm stage is dominated by downdrafts?

Accepted Answer

The dissipating stage is characterized by strong downdrafts spreading out at the surface as the storm rains itself out.

Question 15

Structural icing on an aircraft requires two conditions:

Accepted Answer

Structural icing (ice forming on wings/props) happens only if there is visible moisture (clouds/rain) AND the aircraft surface temperature is 0°C or colder.

Question 16

Dew point is defined as:

Accepted Answer

Dew point is the temperature to which air must be cooled to become saturated (100% relative humidity). When temperature equals dew point, fog or dew forms.

Question 17

If the temperature and dew point are within 3°C (5°F) of each other, what weather condition should you expect?

Accepted Answer

When the temperature/dew point spread is small (less than 3°C), the air is near saturation, making fog and low clouds highly likely.

Question 18

A lenticular cloud (almond or lens-shaped) is often a sign of:

Accepted Answer

Standing lenticular clouds form over mountain crests/ridges in stable air with strong winds, indicating severe turbulence and mountain wave activity.

Question 19

METAR is an acronym for:

Accepted Answer

METAR stands for Aviation Routine Weather Report. It provides current weather observation data.

Question 20

A TAF (Terminal Aerodrome Forecast) is valid for a radius of _____ from the center of the airport runway complex.

Accepted Answer

A TAF is a forecast established for the 5 statute mile radius around an airport.

Question 21

In a METAR, the wind direction is given in degrees relative to:

Accepted Answer

In written weather reports (METAR/TAF), wind direction is True North. If heard over the radio (ATIS/Tower), it is Magnetic. 'If you read it, it's True. If you hear it, it's Magnetic.'

Question 22

Decode the following METAR wind group: 18004KT

Accepted Answer

18004KT means the wind is coming FROM 180 degrees True at 4 knots.

Question 23

Decode this METAR sky condition: OVC007

Accepted Answer

Cloud heights are reported in hundreds of feet AGL. 007 means 700 feet.

Question 24

In a METAR, 'VRB' in the wind group indicates:

Accepted Answer

VRB indicates variable wind direction, typically when wind speed is 6 knots or less.

Question 25

What constitutes a 'Ceiling' for aviation purposes?

Accepted Answer

A ceiling is defined as the height of the lowest layer of clouds reported as Broken (BKN) or Overcast (OVC), or Vertical Visibility (VV) into an obscuration.

Question 26

Which cloud layer code represents a ceiling?

Accepted Answer

Broken (BKN) and Overcast (OVC) constitute a ceiling. Scattered (SCT) and Few (FEW) do not cover enough sky (less than 5/8) to be a ceiling.

Question 27

METAR snippet: 22015G25KT. What is the wind velocity?

Accepted Answer

15 is the sustained speed, G25 indicates gusts up to 25 knots.

Question 28

In a METAR, 'RA' indicates rain. What does '-RA' indicate?

Accepted Answer

A minus sign (-) precedes weather phenomena to indicate 'Light' intensity. No sign is moderate. A plus sign (+) is heavy.

Question 29

Decode: BR

Accepted Answer

BR stands for Mist (from the French 'Brume'). It is used when visibility is between 5/8 SM and 6 SM.

Question 30

Decode: TSRA

Accepted Answer

TS = Thunderstorm, RA = Rain. Combined it means Thunderstorm with Rain.

Question 31

What does 'SPECI' indicate at the beginning of a weather report?

Accepted Answer

SPECI indicates a non-routine (special) aviation weather report issued because weather conditions changed significantly before the next hourly report.

Question 32

You see 'WS010/18045KT' in a TAF. This indicates:

Accepted Answer

WS indicates Wind Shear. 010 indicates the height (1,000 feet AGL). 18045KT is the wind direction/speed at that height.

Question 33

Refer to METAR: KINK 121845Z 11012G18KT 15SM SKC 25/17 A3000. What is the temperature?

Accepted Answer

The temp/dewpoint group is '25/17'. The first number is air temperature in Celsius (25°C). The second is dew point (17°C).

Question 34

Refer to METAR: KJFK 121853Z 1/2SM FG VV002. Can you fly under Part 107?

Accepted Answer

Visibility is 1/2 Statute Mile (1/2SM). Part 107.51(c) requires 3 SM visibility. Flight is prohibited.

Question 35

In a TAF, 'FM' (e.g., FM1200) means:

Accepted Answer

FM indicates 'From'. It denotes a rapid change in prevailing conditions starting at the time listed (1200Z).

Question 36

In a TAF, 'PROB30' indicates:

Accepted Answer

PROB30 indicates a 30% chance of the specified conditions occurring during the listed time period.

Question 37

Standard temperature and pressure at sea level is:

Accepted Answer

Standard atmosphere is defined as 15°C (59°F) and 29.92" Hg (1013.2 mb) at sea level.

Question 38

What creates a temperature inversion?

Accepted Answer

Normally temperature decreases with altitude. An inversion occurs when temperature increases with altitude (warm air traps cold air below it), leading to stable air and poor visibility/fog.

Question 39

Refer to METAR: 30010KT 10SM CLR 02/M02 A3012. The spread between temp and dewpoint is:

Accepted Answer

Temp is 02°C. Dewpoint is M02 (-2°C). The difference (spread) is 2 - (-2) = 4 degrees.

Question 40

Thunderstorms reach their greatest intensity during the:

Accepted Answer

The mature stage is the most intense, characterized by precipitation at the surface, lightning, and strong updrafts/downdrafts.

Question 41

During the life cycle of a thunderstorm, which stage is characterized predominantly by updrafts?

Accepted Answer

The Cumulus stage consists of continuous updrafts that build the cloud vertically.

Question 42

The wind at 3,000 feet AGL is often different from surface wind due to:

Accepted Answer

Surface friction slows the wind and changes its direction (Coriolis force is weaker). Aloft, friction is negligible, so winds are stronger and flow parallel to isobars.

Question 43

What is the primary danger of a Microburst?

Accepted Answer

Microbursts are small-scale intense downdrafts that spread outward at the surface, creating severe wind shear that can crash aircraft.

Question 44

Which weather condition is indicated by a 'Squall Line' on a chart?

Accepted Answer

A squall line is a narrow band of active thunderstorms, often forming ahead of a cold front in moist, unstable air. It creates the most severe weather hazards to aircraft.

Aviation Weather Practice Questions

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