21 Aviation Weather Practice Questions & Answers

1. 1. A routine hourly surface observation for an airport reports few clouds at 800 feet, scattered clouds at 1,500 feet, broken clouds at 2,500 feet, and an overcast layer at 6,000 feet. What is the reported ceiling, and what is it measured above?

   • A.A ceiling of 2,500 feet above mean sea level, since layer heights in a surface report are given above the sea.
   • B.A ceiling of 2,500 feet above ground level, since a ceiling is the lowest broken or overcast layer.✓ Answer
   • C.A ceiling of 800 feet above ground level, since the lowest layer of any amount of cloud sets the ceiling.
   • D.A ceiling of 6,000 feet above ground level, since only a completely overcast layer can count as a ceiling.

   A ceiling is the height above ground level of the lowest layer reported as broken or overcast, or the vertical visibility into an obscuration. Few and scattered layers are never ceilings, so the broken layer at 2,500 feet is the ceiling, and cloud heights in a surface observation are always above ground level, not above sea level.

   Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 13 (Aviation Weather Services), METAR sky condition and ceilingReport a problem with this question

2. 2. An evening surface observation at your destination reports calm wind, clear sky, temperature 12 °C and dew point 11 °C, and the sky is forecast to stay clear all night. You plan to arrive shortly after sunrise. Which hazard should you plan for?

   • A.Advection fog around sunrise, because a calm and clear night lets warm moist air drift over a cooler surface.
   • B.Low-level wind shear around sunrise, because calm surface wind under a clear sky builds a strong shear zone.
   • C.Radiation fog around sunrise, because the ground cools the shallow moist layer to its dew point overnight.✓ Answer
   • D.Freezing rain around sunrise, because the small spread shows that a deep layer of warmer air lies above the field.

   Radiation fog forms over land on clear nights with little or no wind when a shallow moist layer is cooled by the ground to its dew point, and a temperature and dew point spread of only 1 °C shows the air is already nearly saturated. Advection fog needs wind moving warm moist air over a colder surface, which a calm night does not provide.

   Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), fogReport a problem with this question

3. 3. A terminal aerodrome forecast is issued with the valid period group 1218/1324. Over what period is that forecast valid?

   • A.From 1800Z on the 12th of the month until 2400Z on the 13th of the month.✓ Answer
   • B.From 1218Z until 1324Z on the same day that the forecast was prepared and issued.
   • C.From 1200Z on the 12th until 1300Z on the 13th, followed by an 18-hour outlook.
   • D.From 1200Z on the 18th of the month until 1300Z on the 24th of the same month.

   In a terminal forecast the valid period is written as two groups of four digits, each giving the day of the month followed by the hour in coordinated universal time. So 1218/1324 begins at 1800Z on the 12th and ends at 2400Z on the 13th, a 30-hour period.

   Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 13 (Aviation Weather Services), terminal aerodrome forecastReport a problem with this question

4. 4. A terminal forecast contains a TEMPO group covering a two-hour window that shows visibility 1 statute mile in thunderstorms and rain. How should a pilot read that group?

   • A.As a 40 percent probability that the stated conditions will occur at some point during that window.
   • B.As a gradual change that starts at the beginning of the window and is complete by the end of it.
   • C.As temporary fluctuations, each lasting under an hour and together covering less than half the window.✓ Answer
   • D.As the prevailing conditions for that entire window, superseding everything stated in the preceding group.

   A TEMPO group describes temporary fluctuations expected to last less than one hour at a time and, in total, less than half of the stated window, so it is not the prevailing forecast. A gradual change is shown by BECMG and a stated likelihood by PROB40, and a pilot who reads a TEMPO group as prevailing weather will plan for conditions that are not forecast to dominate.

   Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 13 (Aviation Weather Services), TAF change groupsReport a problem with this question

5. 5. In a winds and temperatures aloft forecast, the entry for the 30,000-foot level at a station is coded 7545. What does that entry tell the pilot?

   • A.Wind from 250° true at 145 knots, because 50 is added to the direction and 100 subtracted from the speed.✓ Answer
   • B.Wind from 250° magnetic at 145 knots, because winds aloft forecasts are referenced to magnetic north, not true.
   • C.Wind from 250° true at 45 knots, because only the direction digits carry the added 50 in this coded group.
   • D.Wind from 075° true at 45 knots, read directly, because no coding adjustment is applied at this level.

   Speeds of 100 to 199 knots are coded by adding 50 to the two direction digits and subtracting 100 from the speed, so 7545 decodes as 75 minus 50 equals 250 degrees and 45 plus 100 equals 145 knots. Forecast winds aloft are referenced to true north rather than magnetic north, which is the classic trap in this decoding task.

   Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 13 (Aviation Weather Services), winds and temperatures aloft forecastReport a problem with this question

6. 6. A winds and temperatures aloft forecast for a station whose field elevation is 1,200 feet MSL shows a wind but no temperature for the 3,000-foot level. What explains the missing temperature?

   • A.Temperatures are not forecast for a level within 2,500 feet of the station elevation.✓ Answer
   • B.Temperatures are omitted whenever the forecast value at that level would be above freezing.
   • C.Temperatures are not forecast below 6,000 feet, since a standard lapse rate is assumed in that layer.
   • D.Temperatures are omitted at the lowest level shown, since the sign is printed only above it.

   No wind is forecast for a level within 1,500 feet of the station elevation and no temperature is forecast for a level within 2,500 feet of it, because values that close to the surface are not meaningful for the forecast. A field at 1,200 feet is 1,800 feet below the 3,000-foot level, so the wind is published but the temperature is not.

   Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 13 (Aviation Weather Services), winds and temperatures aloft forecastReport a problem with this question

7. 7. Which report from an airborne pilot would be transmitted as an urgent pilot report rather than a routine one?

   • A.Severe icing encountered during a descent through cloud on the approach.✓ Answer
   • B.Moderate turbulence encountered while cruising just below a broken cloud deck.
   • C.Cloud tops found 2,000 feet higher than the area forecast had indicated.
   • D.Light rime ice that built up slowly during a long climb through stratus.

   An urgent pilot report is used for conditions hazardous to any aircraft: tornadoes or funnel clouds, severe or extreme turbulence, severe icing, hail, low-level wind shear, and volcanic ash. Moderate turbulence, light icing and a tops observation are valuable but are filed as routine reports, and a pilot report remains the only direct observation of actual conditions in flight.

   Source: Aeronautical Information Manual, Chapter 7, Section 1 (Pilot Weather Reports)Report a problem with this question

8. 8. An AIRMET Tango has been issued along your route of flight. Which hazard does that advisory describe?

   • A.Severe or extreme clear air turbulence that is not associated with a thunderstorm.
   • B.Moderate turbulence, surface winds of 30 knots or more, or low-level wind shear.✓ Answer
   • C.Moderate icing aloft together with the height of the freezing level along the route.
   • D.Instrument flight rules ceilings and visibilities and widespread mountain obscuration.

   AIRMETs cover en route hazards below severe thresholds and are aimed at lighter aircraft: Sierra covers instrument conditions and mountain obscuration, Tango covers moderate turbulence, sustained surface winds of 30 knots or more and non-convective low-level wind shear, and Zulu covers moderate icing and freezing levels. Severe or extreme turbulence is instead the subject of a SIGMET.

   Source: Aeronautical Information Manual, Chapter 7, Section 1 (AIRMET)Report a problem with this question

9. 9. A convective SIGMET has been issued for a line of thunderstorms crossing your route. What does its issuance always imply?

   • A.Moderate turbulence and moderate icing below 18,000 feet MSL within the affected area.
   • B.Instrument conditions and mountain obscuration throughout the whole of the affected area.
   • C.Severe or greater turbulence, severe icing and low-level wind shear within the area.✓ Answer
   • D.Hail of 3/4 inch or larger only, since turbulence and icing require a separate advisory.

   Any convective SIGMET implies severe or greater turbulence, severe icing and low-level wind shear, because those hazards accompany the thunderstorm activity that triggers the advisory. It is issued for severe thunderstorms, embedded storms, a line of storms or heavy precipitation over a large area, and it is valid for up to one hour.

   Source: Aeronautical Information Manual, Chapter 7, Section 1 (Convective SIGMET)Report a problem with this question

10. 10. You telephone Flight Service seven hours before your proposed departure to see whether the trip looks feasible. Which type of briefing should you request?

    • A.An inflight briefing, which supplies forecast amendments issued after a flight plan is filed.
    • B.An abbreviated briefing, used to update information already obtained from another source.
    • C.A standard briefing, the only type in which the briefer volunteers adverse conditions first.
    • D.An outlook briefing, which is for planning only and must be followed by another briefing.✓ Answer

    An outlook briefing is requested when the proposed departure is six or more hours away, and it is for planning purposes only, so a standard or abbreviated briefing must still be obtained closer to departure. A standard briefing is the full briefing given when no previous information has been received, and it opens with adverse conditions.

    Source: Aeronautical Information Manual, Chapter 7, Section 1 (Preflight Briefings)Report a problem with this question

11. 11. Warm, moist and stable air is forced to flow up a long mountain slope. What clouds and weather should a pilot expect?

    • A.Stratus-type clouds with steady precipitation and poor visibility in smooth but stable air.✓ Answer
    • B.Little cloud but strong thermal turbulence, because stable air keeps its moisture as vapor.
    • C.Standing lenticular clouds with severe rotor turbulence directly over the windward slope.
    • D.Towering cumulus with showers and turbulence, because upslope lifting always releases instability.

    Stable air resists vertical motion, so when it is lifted mechanically the moisture spreads out into layered stratiform cloud rather than building upward. The result is steady precipitation, smooth flight conditions and restricted visibility, while cumuliform cloud with showers and turbulence would indicate that the lifted air was unstable.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), atmospheric stabilityReport a problem with this question

12. 12. Which statement describes a temperature inversion and the conditions a pilot should expect inside that layer?

    • A.Temperature decreases rapidly with altitude, giving an unstable layer with showers and turbulence.
    • B.Temperature increases with altitude, giving a very stable layer with smooth air and poor visibility.✓ Answer
    • C.Temperature stays constant with altitude, giving a neutral layer with unrestricted visibility.
    • D.Temperature increases with altitude, giving an unstable layer with strong convective currents.

    An inversion is a layer in which temperature increases rather than decreases with height, most often forming overnight near the surface on a clear, relatively still night. Because warmer air sits above cooler air the layer is very stable and the flight is smooth, but smoke, dust and moisture are trapped beneath the inversion, so visibility within it is poor.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), temperature inversionsReport a problem with this question

13. 13. Which set of conditions produces advection fog?

    • A.Cold dry air moving over much warmer water, so that shallow fog appears to rise off it.
    • B.Moist stable air cooled to its dew point as it is forced up gently sloping terrain.
    • C.Clear sky, little or no wind, and a shallow moist layer over land cooling after sunset.
    • D.Warm moist air moving horizontally over a cooler surface, with wind present to sustain it.✓ Answer

    Advection fog forms when wind moves warm, moist air horizontally over a surface that is cold enough to cool it to its dew point, which is why it is common on coastlines and can deepen rather than clear in wind up to about 15 knots. The other choices describe upslope fog, radiation fog and steam fog, each of which needs a different mechanism.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), types of fogReport a problem with this question

14. 14. Why must frost be removed from the wings before flight?

    • A.It disturbs the smooth flow of air over the wing, decreasing lift and increasing drag.✓ Answer
    • B.It adds enough weight to the airframe to move the center of gravity past its aft limit.
    • C.It changes the shape of the airfoil in a way that increases lift and lowers the stall speed.
    • D.It blocks the pitot opening and the static ports, making the airspeed indicator read high.

    Frost forms by deposition when a surface is at or below both freezing and the dew point of the adjacent air, and although the deposit is thin it roughens the wing enough to cause early airflow separation. The result is less lift and more drag, so the airplane may fail to become airborne at normal takeoff speed, which is why frost must be removed rather than polished smooth.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), frostReport a problem with this question

15. 15. Under what conditions does clear (glaze) ice form on an airframe in flight?

    • A.Water vapor depositing directly as ice on a cold airframe parked outside on a clear, still night.
    • B.Small supercooled droplets freezing instantly in cold cloud, leaving a rough, milky, brittle deposit.
    • C.Large supercooled drops freezing slowly in warmer cloud, spreading back as heavy, clear ice.✓ Answer
    • D.Snow striking a wing warmer than freezing and refreezing as a film behind the leading edge.

    Clear ice forms when relatively large supercooled drops strike the airframe at temperatures near freezing and freeze slowly, so the water flows back over the surface before it solidifies into a hard, heavy, glossy layer with horns near the leading edge. Rime ice, by contrast, comes from small droplets freezing instantly in colder cloud and is rough, milky and brittle.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), structural icingReport a problem with this question

16. 16. In an airplane with a fixed-pitch propeller, which conditions favor carburetor icing, and what is the first indication?

    • A.Visible moisture with an outside air temperature below freezing, shown first by a rise in engine RPM.
    • B.High humidity with an outside air temperature well below 0 °F, shown first by a rough magneto check.
    • C.Dry air at any temperature above freezing, shown first by a drop in the oil temperature indication.
    • D.High humidity with an outside air temperature of roughly 20 °F to 70 °F, shown first by a drop in RPM.✓ Answer

    The pressure drop and fuel vaporization in the carburetor venturi can cool the incoming air by tens of degrees, so ice can form in high humidity at outside air temperatures roughly between 20 °F and 70 °F, even in clear air well above freezing. With a fixed-pitch propeller the restricted airflow shows up first as a gradual loss of engine RPM, while a constant-speed installation shows a loss of manifold pressure.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 7 (Aircraft Systems), induction icingReport a problem with this question

17. 17. What marks the beginning of the mature stage of a thunderstorm?

    • A.The anvil top spreads downwind and the cell becomes dominated entirely by downdrafts.
    • B.A continuous updraft builds towering cumulus while no precipitation reaches the ground.
    • C.Precipitation begins to reach the surface and downdrafts join the existing updrafts.✓ Answer
    • D.The cloud top reaches the tropopause and lightning is first detected within the cell.

    The mature stage begins when precipitation starts to reach the surface, because the falling rain drags air down and creates a downdraft alongside the updraft that built the cell. That coexistence of strong up and down currents makes the mature stage the most hazardous, while the cumulus stage has updrafts only and the dissipating stage, marked by the anvil, is dominated by downdrafts.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), thunderstorm life cycleReport a problem with this question

18. 18. Which description matches a microburst encountered on final approach?

    • A.A slow frontal wind shift that gradually reduces the headwind over the last mile of the approach.
    • B.A steady downslope wind several miles wide that lasts for hours and gives a constant tailwind on final.
    • C.A band of turbulence above 15,000 feet that reaches the ground as a slow loss of indicated airspeed.
    • D.An intense downdraft under 2.5 miles wide that gives a headwind gain, then a downdraft and a tailwind.✓ Answer

    A microburst is a small, intense downdraft typically less than 2.5 miles across that lasts only about 5 to 15 minutes but can produce downdrafts of several thousand feet per minute and headwind-to-tailwind changes of 30 to 90 knots. On approach the aircraft first meets a performance-increasing headwind, then the downdraft, then a performance-decreasing tailwind, which is why it is the most severe form of low-level wind shear.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), microbursts and wind shearReport a problem with this question

19. 19. While cruising cross-country you cross a surface front. Which change is the first reliable indication that the front has passed?

    • A.A shift in wind direction, since the wind changes as the boundary between two air masses passes.✓ Answer
    • B.A steady fall in the altimeter setting, since surface pressure keeps dropping after a front passes.
    • C.An increase in reported visibility, since drier and clearer air always follows behind a frontal passage.
    • D.A rise in outside air temperature, since the air behind a front is warmer than the air ahead of it.

    A front is the boundary between two air masses, and the most reliable single indication that it has passed is a change in wind direction, which always accompanies the passage. Temperature, dew point and visibility changes depend on which kind of front it is, and pressure characteristically falls as the front approaches and then rises once it has gone by.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), air masses and frontsReport a problem with this question

20. 20. Around a surface low-pressure system in the Northern Hemisphere, how does the air move and what weather usually results?

    • A.Clockwise and inward, and the air rises along the isobars, so widespread fog and haze develop.
    • B.Clockwise and outward, and the diverging air sinks, so fair weather and good visibility follow it.
    • C.Counterclockwise and inward, and the converging air rises and cools, so cloud and precipitation are common.✓ Answer
    • D.Counterclockwise and outward, and air sinks over the center, so the sky clears beneath the low.

    In the Northern Hemisphere air spirals counterclockwise and inward around a surface low because friction near the ground turns the wind across the isobars toward the lower pressure. That convergence forces air upward, cooling it and producing cloud and precipitation, while a high has clockwise, outward flow with subsiding air and generally fair weather.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), atmospheric circulation and windReport a problem with this question

21. 21. A strong wind is blowing perpendicular to a mountain ridge through a stable layer. What should a pilot expect on the downwind side of the ridge?

    • A.Downdrafts and turbulence, with standing lenticular and rotor clouds marking the wave when moist.✓ Answer
    • B.Thunderstorms and hail, because forcing stable air over a ridge releases the instability stored in it.
    • C.Calm conditions below ridge level, with the strongest turbulence several thousand feet above the peaks.
    • D.Updrafts and smooth air, because the ridge shelters the lee side and the wave forms only upwind.

    When stable air is forced over a ridge it oscillates downstream as a mountain wave, producing strong downdrafts immediately in the lee and turbulence that is most severe in the rotor beneath the wave crests. If enough moisture is present the wave is marked by standing lenticular clouds, which remain stationary despite the strong wind, together with rotor and cap clouds.

    Source: FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, Chapter 12 (Weather Theory), mountain wave turbulenceReport a problem with this question

Practice questions based on the aeronautical knowledge areas codified at 14 CFR 61.105(b) and on FAA handbooks (the Pilot's Handbook of Aeronautical Knowledge, the Airplane Flying Handbook) and the Aeronautical Information Manual. This site is not affiliated with or endorsed by the FAA. Taking the real knowledge test requires an endorsement from an authorized instructor or evidence of completing a ground training course. Charts, weather products and aircraft performance data are republished on a cycle — always fly and test from current official sources. About FAA airman testing →