Part 107 weather questions ask you to connect three different things: a METAR reports observed airport weather, a TAF forecasts terminal weather over a stated period, and density altitude describes how thin or dense the air is in terms of a standard-atmosphere altitude. Read the weather product's date, time, units, and height reference before deciding what it means for a flight.
The FAA's Remote Pilot Airman Certification Standards, FAA-S-ACS-10B, list METARs under UA.III.A.K2, TAFs under UA.III.A.K3, and density altitude under UA.III.B.K1a. The exercises below are original teaching examples, not actual FAA exam questions or live weather reports.
On This Page
- Decode a METAR one group at a time
- Find the ceiling and keep the height reference
- Read a TAF as a timeline
- Connect cloud reports to Part 107 limits
- Explain density altitude before calculating it
- Practice with changed inputs
Decode a METAR one group at a time
A METAR is an observation for its reporting location and time. A SPECI is a special observation issued when specified changes warrant one. Automated Surface Observing System equipment, or ASOS, measures weather variables used in these reports; the National Weather Service ASOS overview explains the sensors and reported elements.
Work through this fictional report using the NWS METAR decoding key:
METAR KICT 151853Z 19014G22KT 6SM -RA SCT018 BKN032 OVC060 24/21 A2994
Worked METAR translation
| Group | Meaning in this example |
|---|---|
METAR KICT | Routine observation for the station identified as KICT |
151853Z | Day 15 of the month, 18:53 UTC |
19014G22KT | Wind from 190 degrees true at 14 knots, gusting to 22 knots |
6SM | Prevailing visibility of 6 statute miles |
-RA | Light rain |
SCT018 BKN032 OVC060 | Scattered clouds at 1,800 feet, broken at 3,200 feet, overcast at 6,000 feet above the reporting location |
24/21 | Temperature 24°C; dew point 21°C |
A2994 | Altimeter setting 29.94 inches of mercury |
The values are invented for practice; the coding follows the NWS key. Notice that wind direction describes where the air comes from. Neither the speed nor the gust value is in miles per hour. The three cloud-height digits represent hundreds of feet.
Read 24/21 in order: temperature first, dew point second. An M before a temperature
means minus, so M03/M05 means −3°C and −5°C. Do not confuse the altimeter setting with
airport elevation or the pressure measured directly at a high-elevation station.
Practice question: What is the reported gust speed: 14, 22, or 190 knots? The answer
is 22 knots, the value after G. Answering 14 reads the sustained wind; answering
190 mistakes direction for speed.
Find the ceiling and keep the height reference
The FAA Pilot/Controller Glossary's ceiling definition identifies the lowest qualifying broken, overcast, or obscuration layer. A few or scattered cloud layer does not establish a ceiling.
In the practice METAR, the ceiling is therefore 3,200 feet above the reporting
location, from BKN032. Selecting 1,800 feet chooses the lowest cloud layer, but that
layer is scattered. Selecting 6,000 feet skips a lower qualifying broken layer.
The
FAA Aeronautical Information Manual's weather section
explains cloud coding, including vertical visibility into an obscuration. VV003 means
vertical visibility of 300 feet into an indefinite ceiling. It is not a measurement of a
distinct cloud base.
Height above ground level, or AGL, differs from altitude above mean sea level, or MSL. Suppose an exercise gives a reporting-station elevation of 1,400 feet MSL and a cloud base of 3,200 feet above that station. The calculated cloud-base altitude is 1,400 + 3,200 = 4,600 feet MSL. Those are hypothetical inputs, not KICT's actual elevation.
That conversion does not establish cloud clearance at a distant drone site. Terrain elevation and actual clouds may differ. Keep the reporting location attached to the number instead of treating airport AGL as height above every nearby launch point.
Read a TAF as a timeline
A TAF describes expected conditions for a terminal area and a defined period. First find
its issue time, then its validity window, then the period containing the time in the
question. The
Aviation Weather Center's TAF guidance
explains FM, TEMPO, and probability groups.
Consider this fictional forecast:
TAF KICT 151730Z 1518/1618 18010KT P6SM SCT040
FM152100 22015G25KT 5SM SHRA BKN025
TEMPO 1521/1523 2SM TSRA BKN012CB
FM160100 30008KT P6SM SCT030
It was issued on day 15 at 17:30 UTC. It is valid from day 15 at 18:00 UTC through day
16 at 18:00 UTC. P6SM means visibility greater than 6 statute miles; SHRA means rain
showers, TSRA thunderstorms with rain, and CB cumulonimbus.
Worked TAF timeline
| Time asked about | Applicable forecast | Answer |
|---|---|---|
| Day 15, 19:00 UTC | Initial conditions | Wind from 180° at 10 knots; visibility greater than 6 miles; scattered clouds at 4,000 feet AGL |
| Day 15, 22:00 UTC | FM152100, plus the active TEMPO window | Prevailing visibility 5 miles and broken ceiling 2,500 feet; temporary visibility 2 miles and broken ceiling 1,200 feet with thunderstorms and rain |
| Day 16, 02:00 UTC | FM160100 | Wind from 300° at 8 knots; visibility greater than 6 miles; scattered clouds at 3,000 feet AGL |
The timeline applies the AWC rules to invented values. An FM group replaces the prevailing conditions beginning at its specified day, hour, and minute. A TEMPO group changes only the listed elements temporarily; unchanged elements carry over. Thus, the temporary group above does not erase the forecast wind of 220° at 15 knots, gusting to 25.
The 22:00 question needs careful wording. If it asks for prevailing visibility, answer 5 miles. If it asks what temporary visibility is forecast during that window, answer 2 miles. The forecast does not promise that the temporary condition will occur at precisely 22:00. AWC describes TEMPO fluctuations as lasting no more than an hour per episode and less than half the stated window in total.
FM160100 means 01:00 UTC on day 16. Keep all groups in UTC while solving the timeline.
Convert to local time only if requested, using the offset for the specified place and
date; crossing midnight can change the calendar day. A PROB30 group indicates a 30
percent probability, rather than 30 minutes of weather.
Connect cloud reports to Part 107 limits
Under the ordinary limits in 14 CFR 107.51(c) and (d), flight visibility observed from the control station must be at least 3 statute miles. The aircraft must remain at least 500 feet below clouds and 2,000 feet horizontally from clouds.
For a simplified exercise, assume a level site with an actual overcast base 800 feet above it. At 350 feet AGL, the aircraft is only 800 − 350 = 450 feet below the cloud, which fails the vertical requirement. At 300 feet AGL, the calculated separation is 500 feet. That is the vertical boundary in this scenario, not permission to launch: horizontal separation, visibility, other operating limits, and changing conditions still matter.
A scattered layer may not be a ceiling, but its individual clouds still count for separation. Likewise, a favorable airport METAR does not replace the visibility assessment at the control station. In the TAF example, the temporary 2-mile visibility forecasts conditions below the ordinary minimum if they occur at the operating site.
Explain density altitude before calculating it
Higher density altitude means thinner air and generally reduced aircraft performance. It is possible to be close to the ground while operating in air that corresponds to a much higher standard-atmosphere altitude.
The FAA's Remote Pilot Study Guide, Chapter 3b, explains the contributing factors. At otherwise equal conditions, higher temperature, lower pressure, and greater water-vapor content reduce air density. Higher elevations also commonly mean lower pressure. Humid air is less dense than dry air at the same temperature and pressure, despite how heavy a humid day may feel.
Practice question: At the same site and pressure, which gives higher density altitude: 15°C or 32°C? Choose 32°C. The warmer air is less dense. Do not read “high density altitude” as “high air density”; they move in opposite directions.
Worked density-altitude estimate
For a numerical exercise, use the approximation described in the FAA's July/August 2010 Safety Briefing, page 14:
Density altitude in feet ≈ pressure altitude in feet + 120 × (outside air temperature in °C − standard temperature in °C at that pressure altitude).
Assume the exercise supplies a pressure altitude of 4,000 feet, a standard temperature there of 7°C, and an actual temperature of 27°C. These are teaching inputs, not observed conditions.
- Temperature above standard: 27 − 7 = 20°C.
- Approximate correction: 120 × 20 = 2,400 feet.
- Estimated density altitude: 4,000 + 2,400 = 6,400 feet.
The result describes air density for performance purposes. The aircraft has not climbed to 6,400 feet, and the number does not change its legal AGL altitude limit. The factor 120 requires Celsius; entering Fahrenheit produces the wrong result. Also use standard temperature at the given pressure altitude, rather than automatically substituting the sea-level value of 15°C.
This approximation omits humidity and cannot predict a particular drone's payload capacity, flight time, or climb rate. The study guide explains the general performance effects; aircraft-specific limitations and performance information remain necessary. The aerodynamic implication for an electric multicopter is that its propellers still operate in thinner air. That does not mean its motor loses power through the same combustion-air mechanism described for a piston engine.
Practice with changed inputs
Use the worked examples as exercises you can modify. Replace BKN032 with SCT032: the
ceiling in the first report then moves to OVC060, or 6,000 feet. Move the TAF question
from 22:00 on day 15 to 02:00 on day 16: the later FM group becomes controlling. Reduce
the density-altitude exercise's temperature to 17°C: the same approximation gives
4,000 + 120 × (17 − 7) = 5,200 feet.
For each answer, say which group, unit, or assumption determined it. That makes a mistake easier to diagnose than memorizing an answer letter. Before a real flight, obtain current weather, check the reporting time and location, and assess conditions at the operating site. These three topics also sit within a broader FAA weather syllabus that includes stability, fronts, thunderstorms, fog, icing, and wind effects.
Sources
- FAA Remote Pilot Airman Certification Standards, FAA-S-ACS-10B: official tested knowledge areas, including weather sources and performance effects.
- NWS ASOS overview: official description of automated weather observations.
- NWS METAR decoding key: report groups, units, weather abbreviations, and temperature notation.
- FAA Pilot/Controller Glossary, C: the operational definition of ceiling.
- FAA AIM, Chapter 7, Section 1: weather-code interpretation, cloud heights, vertical visibility, and forecast time groups.
- NWS Aviation Weather Center product guidance: TAF validity and FM, TEMPO, and PROB30 interpretation.
- 14 CFR 107.51: the operating rule for visibility and cloud separation.
- FAA Remote Pilot Study Guide, Chapter 3b: atmospheric density and small-aircraft performance. Used for physical principles, not its older regulatory material.
- FAA Safety Briefing, July/August 2010, pages 12–14: density-altitude explanation and the approximate temperature-correction calculation.
Last checked: September 7, 2026.