METAR and TAF decoding for the Part 107 test

A METAR looks like a string of noise until you know that every group sits in a fixed order and means one thing. Once you learn the order, a report takes about as long to read as a sentence.

That skill does two jobs. The ACS lists METARs and TAFs as separate knowledge elements for the test. And Part 107 sets weather minimums you have to confirm before flying: 3 statute miles of visibility from the control station, and 500 feet below and 2,000 feet horizontally from clouds.

Keep the METAR decoder open in another tab while you work through this.

The METAR, group by group

The FAA’s Pilot’s Handbook of Aeronautical Knowledge uses this real-format example:

METAR KGGG 161753Z AUTO 14021G26KT 3/4SM +TSRA BR BKN008 OVC012CB 18/17 A2970 RMK PRESFR

Group	Example	Meaning
Type	`METAR`	Routine report. `SPECI` is a special report issued between routine ones
Station	`KGGG`	Four-letter ICAO code; K plus three letters in the 48 contiguous states
Date and time	`161753Z`	16th of the month, 17:53 UTC (Z)
Modifier	`AUTO`	Automated station. `COR` means a corrected report
Wind	`14021G26KT`	From 140° true at 21 knots, gusting 26
Visibility	`3/4SM`	Three-quarters of a statute mile
Weather	`+TSRA BR`	Thunderstorm with heavy rain, and mist
Sky condition	`BKN008 OVC012CB`	Broken at 800 ft, overcast at 1,200 ft with cumulonimbus
Temp and dew point	`18/17`	18 °C and 17 °C
Altimeter	`A2970`	29.70 inches of mercury
Remarks	`RMK PRESFR`	Pressure falling rapidly

Wind

Wind is five digits: three for the direction the wind blows from, in degrees true, and two for speed in knots. A G introduces the peak gust. VRB means the direction is variable. If the direction swings by more than 60° and the speed is above 6 knots, a second group such as 180V240 gives the range.

Visibility

Prevailing visibility is in statute miles and can be a fraction, like 1 1/2SM. Sometimes runway visual range follows: R17L/1400FT means 1,400 feet down runway 17 left.

Weather

The weather group is built in order: intensity, then descriptor, then the weather itself. Heavy rain showers become +SHRA.

Code	Meaning	Code	Meaning
`-`	Light	`+`	Heavy
no sign	Moderate	`VC`	In the vicinity, 5 to 10 miles away
`TS`	Thunderstorm	`SH`	Showers
`FZ`	Freezing	`RA`	Rain
`SN`	Snow	`DZ`	Drizzle
`GR`	Hail	`GS`	Small hail or snow pellets
`BR`	Mist	`FG`	Fog
`HZ`	Haze	`FU`	Smoke
`SQ`	Squalls	`+FC`	Tornado or waterspout

Sky condition

Each layer is coverage plus height in hundreds of feet AGL. BKN008 is a broken layer at 800 feet above the ground, not at sea level. Cumulonimbus (CB) or towering cumulus (TCU) is added to the layer. VV003 means vertical visibility of 300 feet into an obscuration.

Code	Sky covered
`SKC` or `CLR`	Less than 1/8
`FEW`	1/8 to 2/8
`SCT`	3/8 to 4/8
`BKN`	5/8 to 7/8
`OVC`	8/8

Automated stations don’t detect or report clouds above 12,000 feet, so a clear sky on an AUTO report tells you nothing about clouds higher than that.

A ceiling is the lowest layer reported as broken or overcast, or the vertical visibility into an obscuration. In the KGGG report the ceiling is 800 feet.

Temperature, altimeter, remarks

Temperatures are Celsius, and M means minus: M04/M09. The altimeter setting follows an A in inches of mercury. Remarks start with RMK and can include PRESRR or PRESFR for rising or falling pressure (the handbook decodes PRESFR in its example as falling rapidly), and AO2 for the type of automated sensor.

Applying it to a Part 107 flight

For the KGGG report, visibility is 3/4 statute mile, well under the 3-mile minimum, so the answer is no flight. Even with good visibility, a ceiling at 800 feet would cap you at 300 feet AGL to stay 500 feet below the clouds.

AC 107-2A treats local aviation weather reports as one way to confirm visibility and cloud clearance. Use the closest station most representative of your site’s terrain. If no report is available, you can’t fly until you can determine those minimums by other reliable means. You can’t fly above any cloud.

The TAF

A Terminal Aerodrome Forecast covers the area within 5 statute miles of an airport. It uses the same codes as a METAR, is valid for 24 or 30 hours, and is issued four times a day at 0000Z, 0600Z, 1200Z and 1800Z. An amended forecast is labelled TAF AMD.

The handbook example:

TAF KPIR 111130Z 1112/1212 TEMPO 1112/1114 5SM BR FM1500 16015G25KT P6SM SCT040 BKN250 FM120000 14012KT P6SM BKN080 OVC150 PROB30 1200/1204 3SM TSRA BKN030CB FM120400 1408KT P6SM SCT040 OVC080 TEMPO 1204/1208 3SM TSRA OVC030CB

111130Z issued on the 11th at 11:30 UTC.
1112/1212 valid from the 11th at 12Z to the 12th at 12Z. A period ending at midnight UTC is written as 24.
TEMPO 1112/1114 5SM BR temporarily, between 12Z and 14Z, 5 statute miles in mist.
FM1500 16015G25KT P6SM SCT040 BKN250 from 15Z, wind 160° at 15 gusting 25, visibility more than 6 miles, scattered at 4,000, broken at 25,000.
PROB30 1200/1204 3SM TSRA BKN030CB a 30 percent chance, between 00Z and 04Z on the 12th, of 3 miles in thunderstorms with rain and a broken layer at 3,000 with cumulonimbus.

What’s different from a METAR

Item	TAF rule
`P6SM`	Forecast visibility greater than 6 statute miles
Cloud types	`CB` is the only cloud type forecast; a METAR also reports `TCU`
`FM`	A rapid, significant change, usually within an hour
`TEMPO`	Temporary fluctuations expected to last less than 1 hour
`PROB30`	Probability of thunderstorms or precipitation; not used in the first 6 hours
Wind direction	Referenced to true north, same as the METAR

Where to get reports before a flight

AC 107-2A points remote pilots to Flight Service at 1800wxbrief.com (a free account) and the National Weather Service’s Aviation Weather Center at aviationweather.gov, which needs no registration and carries METARs and TAFs. Check tfr.faa.gov for temporary flight restrictions at the same time.

On the test

Weather carries 11 to 16% in the ACS and 5% under PSI’s current weighting. It’s a small slice, but METAR questions are close to free points once the order is second nature, and the same skill keeps you legal every time you fly.

Mistakes to avoid: reading cloud heights as MSL, forgetting they are in hundreds of feet, and treating a TEMPO group as the main forecast.

For worked questions that combine a METAR with the cloud clearance rule, see Part 107 practice test questions, explained. For how weather feeds into performance, read load factor and density altitude. Then test yourself on the free practice test.