A 30-minute flight from campus today. Move the launch if another time looks better, then commit. It isn’t graded: you check it at the end.
FAA 3 SM visibility · 500 ft below any cloud · 400 ft AGL ATC 100 ft AGL at this field in Class E hours Program 15 kt sustained · 20 kt gust · no precipitation
Right now: what was expected, and what was measured
Same airport, same codes, two different things
Fetching KROG’s latest observation…
The forecast as sent
…
The first line gives the station, when it was issued and the hours it covers, then the forecast those hours open with. Each line after it is a change group. The timeline above is this same text, laid out by the hour.
What this forecast can’t tell you
Whether it will verify. A forecast is what a forecaster expects, not what happens.
Whether a newer TAF or an amendment has replaced it by the time you fly.
What the sky is doing now. That’s the METAR’s job, and your own eyes’.
Conditions at your site. It’s written for the airport, not for campus.
Whether the flight is authorized. From 5:30 AM to 11:00 PM campus is inside the Bentonville Class E surface area, and a flight needs ATC authorization (§ 107.41).
Where any cloud will sit. The 2,000 ft horizontal distance gets settled at the site.
You plan from the forecast. You fly from what you see.
Bellringer
Turn in today’s bellringer
Download the PDF, filled in from your answers with your name and record ID, then upload it to today’s Google Classroom assignment. Your name is only on the PDF; on a shared computer, delete it afterward.
Anatomy of a TAF
Lesson 1 of 8 · Read it · ~5 min
You can already read most of a TAF. Its wind, visibility, weather and sky are written exactly as in a METAR. By the end you can name every part of a TAF’s first line and find it in any forecast.
Find it
Colors off. Tap the group that’s named
Three right in a row, on three different forecasts, completes this lesson.
Not sure of one? Take the first line apart
Tap a group. A training forecast, not a real one
A change group. Everything after the first line is one; Lesson 3 reads them.
A METAR and a TAF, line over line
Group
METARWhat a station measured, at one minute
TAF, first lineWhat a forecaster expects, as its 24 hours open
Product
METAR
TAF
Station
KXNA
KXNA
Time
121153Zwhen it was observed
121130Zwhen it was issued
Valid period
not in a METAR
1212/1312the hours it covers
Wind
16007KT
15008KT
Visibility
5SM
4SM
Weather
-RA BR
-RA BR
Sky
BKN022 OVC040
BKN020 OVC040
Temperature, dew point
18/16
not in a TAF
Altimeter
A2992
not in a TAF
Then
Nothing. It is one moment.
Change groups, for the rest of its 24 hours.
Five things a METAR didn’t teach you
P6SM is more than 6 statute miles, the most a TAF ever says. A METAR would give the number.
SKC is a clear sky in a forecast. An automated METAR writes CLR, which only means nothing was detected at or below 12,000 ft.
A valid period that ends at midnight is written with hour 24: 0900/0924.
TAF AMD is an amended forecast. It replaces the one before it, so read the newest.
A routine TAF is issued four times a day, for 0000Z, 0600Z, 1200Z and 1800Z, and covers 24 hours (30 at the largest airports).
NWSInstruction 10-813
On the test Test-style, on a line of the testing supplement’s TAF figure (Figure 15)
KOKC 051130Z 0512/0618 14008KT 5SM BR BKN030
When was this forecast issued, and what period does it cover?
Issued at 1130Z on the 5th; valid from 1200Z on the 5th to 1800Z on the 6th.
Issued at 0512Z; valid until 0618Z.
Issued at 1130Z on the 5th; valid for 6 hours and 18 minutes from 1200Z.
Answer
A. 051130Z is the issue time: day 5, 1130Z. 0512/0618 is the valid period: day 5 at 1200Z to day 6 at 1800Z. That is 30 hours, the length the largest airports get.
Times and the Valid Period
Lesson 2 of 8 · Read it · ~8 min
A METAR has one time. A TAF is full of them, in two formats. By the end you can put any time in a TAF on the clock, in Zulu and in Arkansas time, across the change of day.
Put it on the clock
The forecast’s own 24 hours, and the hour they end at
Three right in a row, both parts, completes this lesson.
Two formats, and one odd hour
DDHHmm A moment
Day, hour, minute. The issue time and every FM line are written this way, to the minute.
121130Z issued at 1130Z on the 12th FM130200 from 0200Z on the 13th
DDHH/DDHH A span
Day and hour, a slash, day and hour. No minutes. The valid period and every TEMPO or PROB30 window are written this way.
1212/1312 1200Z on the 12th to 1200Z on the 13th TEMPO 1219/1223 between 1900Z and 2300Z
24 Midnight, at the end
A valid period that ends at midnight Zulu is written with hour 24 on the day that is ending, not 00 on the next.
0900/0924 all of the 9th, ending at midnight
NWSInstruction 10-813 Every time in a TAF is Zulu. The day in it is the Zulu day, which in Arkansas turns over in the early evening.
On the test Test-style, on the testing supplement’s TAF figure (Figure 15)
KMEM 121720Z 1218/1324 20012KT 5SM HZ BKN030
What is the valid period for the TAF for KMEM?
1800Z on the 12th to 2400Z on the 13th.
1720Z on the 12th to 1720Z on the 13th.
1200Z on the 18th to 1300Z on the 24th.
Answer
A. 1218/1324 is the valid period: from day 12 at 1800Z to day 13 at 2400Z. 121720Z, just before it, is when the forecast was issued.
Change Groups
Lesson 3 of 8 · Read it · ~10 min
A TAF isn’t one forecast. It’s a timeline. By the end you can say which line is the main forecast at any time, and what else is laid over it.
Which line is the main forecast?
With the timeline
Two right in a row with the timeline folded completes this lesson. Both parts count.
The three change groups a US forecast uses
FM From
A clean break. From the minute it names, this line replaces everything before it and becomes the main forecast, until the next FM line or the end of the valid period.
FM121500 from 1500Z on the 12th
TEMPO Temporary
Laid over the main forecast, never in place of it. The forecaster expects conditions to swing to this, more likely than not, for an hour or less at a time and for less than half of its window. The main forecast still holds underneath.
TEMPO 1219/1223 between 1900Z and 2300Z on the 12th
PROB30 A 30 percent chance
Also laid over the main forecast. A 30 percent chance of a thunderstorm or precipitation during its window, which is never longer than six hours: not likely, and not nothing. It’s the line a plan needs a way out for.
PROB30 1221/1223 between 2100Z and 2300Z on the 12th
NWSInstruction 10-813 sets how US forecast offices write a TAF. An FM time has minutes (day, hour, minute). A TEMPO or PROB30 window is two day-and-hour pairs with a slash between them.
On the test, but not in a US forecast: BECMG and PROB40
BECMG 1306/1308 means a gradual change to the conditions that follow, between 0600Z and 0800Z on the 13th. Until the window ends, either side may hold. PROB40 is a 40 percent chance, read like PROB30.
US forecast offices write FM instead of BECMG and don’t use PROB40. Both still appear in international and military TAFs, and in the FAA’s test figure, so you need to read them.
On the test Test-style
FM121500 18012G20KT P6SM SCT035 TEMPO 1219/1223 4SM TSRA BKN025CB
In this forecast, what does the TEMPO group tell a remote pilot planning a flight at 2100Z?
Thunderstorms with 4 statute miles of visibility may occur at times between 1900Z and 2300Z.
From 1900Z, thunderstorms replace the earlier forecast until 2300Z.
There is a 30 percent chance of thunderstorms after 1900Z.
Answer
A. TEMPO marks temporary fluctuations inside its window. The FM line stays the main forecast the whole time; B describes an FM group, and C describes PROB30.
Time Window Drill
Lesson 4 of 8 · Work it · ~10 min
A METAR gave you one sky to plan under. A TAF gives you a different one for every hour. Pick the line for your flight time, then work out the planning limit under its lowest cloud.
Work it out
Assume the forecast verifies and its layers are over your site. No room under the cloud? Type 0.
That hour’s forecast sky, side view
Vertical distances only
Three right in a row, both parts, completes this lesson.
The arithmetic, and whose numbers they are
500 ftFAA§ 107.51(d) below any cloud
2,000 ftFAA§ 107.51(d) horizontally from any cloud
400 ft AGLFAA§ 107.51(b) maximum altitude, in any airspace class
1the main forecast for your time2its lowest cloud, of any coverage, − 500 ft3then the lower of that and 400 ft
On the test Test-style, on a line of the testing supplement’s TAF figure (Figure 15)
FM122200 33015G20KT P6SM BKN015 OVC025
From 2200Z on the 12th, the forecast ceiling is
1,500 feet AGL.
2,500 feet AGL.
15,000 feet AGL.
Answer
A. A ceiling is the lowest broken or overcast layer, and BKN015 is broken at 1,500 ft. For cloud clearance, though, the lowest layer of any coverage is the one you plan under.
Guided Walkthroughs
Lesson 5 of 8 · Work it · ~10 min
A METAR is read once. A TAF is read forward, line by line, to the hours you care about. Three forecasts, and the help fades: the first is worked for you, the second you tap through, the third you read cold.
On the test Test-style, on a line of the testing supplement’s TAF figure (Figure 15)
Between 1300Z and 1600Z on the 5th, the forecast for KOKC calls for
visibility at times 1 1/2 statute miles in mist.
visibility becoming 1 1/2 statute miles in mist and staying there.
a 30 percent chance of visibility 1 1/2 statute miles in mist.
Answer
A. TEMPO marks temporary fluctuations during its window. The first line, 5 statute miles in mist under a broken layer at 3,000 ft, stays the main forecast throughout.
Did It Verify?
Lesson 6 of 8 · Work it · ~10 min
A forecast is a claim about the future. The METAR is what happened. Six forecasts, each with an observation that followed. By the end you can hold one against the other and say what a pilot does next.
On the test Test-style
A TAF issued this morning forecasts P6SM SKC for 1500Z. The 1453Z METAR for the same airport reports 2SM BR OVC004. Which describes the weather at the airport now?
The METAR. It is an observation; the TAF was a forecast.
The TAF. It covers a longer period, so it outranks a single report.
Neither, until an amended TAF is issued.
Answer
A. A METAR reports what was observed. A TAF says what was expected, and this one hasn’t verified. Plan from the forecast, then check it against the newest observation.
Flight Window Planner
Lesson 7 of 8 · Call it · ~15 min
Three questions, in order: if this forecast verifies, would the numbers meet the minimums, would you plan to fly the mission, and how sure are you? The number to watch is confident and wrong.
The numbers are not the whole call
Clearing the numbers is not the whole obligation. § 107.49 requires the remote PIC to assess the operating area and the weather before every flight; § 107.19 makes the remote PIC directly responsible for the operation, and the final authority over it; § 107.23 prohibits careless or reckless operation. None of those is a number you can read off a TAF. A forecast that breaches no minimum can still be one you decline to fly.
BHS Training Multirotor Profile
In force for every scenarioProgramclassroom limits 15 kt sustained · 20 kt gust · no flight in precipitationDetails
Max sustained wind
15 ktProgram
Max gust
20 ktProgram
Precipitation
Flight not permittedProgram
Program limits are the instructor’s: a classroom training limit, not a universal manufacturer specification. A TAF carries no temperature, so the program’s hot-weather rule has nothing to read here.
On the test Test-style
Before flight, 14 CFR 107.49 requires the remote pilot in command to assess the operating environment, including
local weather conditions.
the TAF for the nearest airport that issues one.
a forecast no more than six hours old.
Answer
A. § 107.49 names local weather conditions. METARs and TAFs are important tools for assessing them, but the rule doesn’t name either one.
Exam Mode
Lesson 8 of 8 · Call it · ~15 min
Ten questions, three choices each, like the real test. No colors and no hints. Four are built fresh each run, so they can’t be memorized.
Decoder
A tool · any TAF, read line by line
Paste any TAF, or fetch one, and read it the way the lessons do. It’s here to check your own reading against, not to do the reading for you.
A forecast to decode
Today’s KXNA forecast, or paste your own
Cheat sheet
Reference · print it for your binder
Every TAF code in one place. The same facts the lessons teach, on one sheet. Print it and only the sheet comes out, colors included.
Part 107 weather minimums
Flight visibility
3 statute miles, judged from your control station
Below any cloud
500 ft
Horizontally from any cloud
2,000 ft
Maximum altitude
400 ft AGL (unless within a 400 ft radius of a structure and no higher than 400 ft above its uppermost limit, § 107.51(b))
At the BHS field
100 ft AGL from 5:30 AM to 11:00 PM ATC§ 107.41 Campus is inside the Bentonville (KVBT) Class E surface area then: a flight needs ATC authorization and stays at or below the altitude it approves. The program’s have been for 100 ft, and the authorization in hand governs. Overnight campus is in Class G and the 400 ft cap applies.
TAF times
UTC (Zulu), every one of them
Cloud clearance applies to every cloud, FEW and SCT included. § 107.51(d) sets 500 ft as the minimum distance below a cloud and 2,000 ft as the minimum distance horizontally from one. Under a layer the 500 ft is what you plan with; where the nearest cloud will actually be isn’t something a forecast can tell you.
The first line, in order
TAF
Product. TAF AMD is an amended forecast, TAF COR a corrected one
KXNA
Station: the airport it is written for, and 5 statute miles around its runways
121130Z
Issue time: day, hour, minute
1212/1312
Valid period: day and hour, to day and hour
15008KT
Wind, as in a METAR
P6SM
Visibility, as in a METAR
-RA BR
Weather, as in a METAR (left out when there is none)
SCT040
Sky, as in a METAR
No temperature, dew point, altimeter or remarks: a TAF doesn’t carry them.
Change groups in a US forecast
FM121500
From. Replaces everything before it, from that minute. The main forecast until the next FM
TEMPO 1219/1223
Temporary. Expected at times in that window, laid over the main forecast: an hour or less at a time, less than half the window
PROB30 1221/1223
A 30 percent chance of a thunderstorm or precipitation in that window, laid over the main forecast
NSW
No significant weather: the weather forecast earlier is expected to end. It doesn’t mean a clear sky. In a US forecast it appears only in a TEMPO line
Only the first line and an FM line are ever the main forecast. TEMPO and PROB30 never replace it.
On the test, not in a US forecast
BECMG 1306/1308
Becoming. A gradual change during that window; until it ends, either side may hold
PROB40 0600/0606
A 40 percent chance, read like PROB30
PROB30 TEMPO
A 30 percent chance of temporary conditions
US forecast offices write FM instead of BECMG and don’t use PROB40. All three appear in international TAFs, and BECMG and PROB40 are in the test’s Figure 15.
Two time formats
DDHHmm
A moment, to the minute: the issue time (121130Z) and every FM (FM130200)
DDHH/DDHH
A span, no minutes: the valid period and every TEMPO or PROB30 window
0900/0924
Hour 24: a valid period ending at midnight Zulu
The day is the Zulu day. In Arkansas it turns over in the early evening, so an FM in the small hours Zulu is the evening before, local.
Wind and visibility
21015G25KT
From 210° true at 15 knots, gusting to 25
VRB03KT
Variable direction: wind of 6 knots or less, or around thunderstorms
1–2, 3–4, 5–7 and 8 eighths of the sky, with the base in hundreds of feet AGL
VV003
Sky obscured, vertical visibility 300 ft
BKN020CB
CB, cumulonimbus: the only cloud type a TAF names
-RA +TSRA SHRA
Light rain; a thunderstorm with heavy rain; rain showers
BR FG HZ
Mist; fog; haze
A ceiling is the lowest BKN, OVC or VV layer. Cloud clearance is about the lowest layer of any coverage. The codes are the METAR’s: its cheat sheet has them all.
TAF and METAR
METAR
What a station measured, at one minute. Hourly, or sooner
TAF
What a forecaster expects, for 24 hours (30 at the largest airports). Issued four times a day, and amended between
§ 107.49 requires the remote PIC to assess local weather conditions; METARs and TAFs are important tools for doing so. Plan from the forecast, then check it against the newest observation and the sky.
Program operating limits
Three different questions
1. Forecast numbers
If it verifies, do the forecast visibility and the lowest forecast layer meet § 107.51? “Would be met” or “would not be met”
2. Site verification
What you can see from the control station, where the clouds actually are, whether a newer TAF is out, what the latest METAR shows
3. Operational call
Operational GO, GO with restrictions, or Operational NO-GO, for the aircraft, the program limits and the forecast’s confidence
A forecast screen is never a clearance. Answer all three, in order.
Traps to watch for
A forecast, not an observation
It says what is expected, not what is happening
TEMPO isn’t the main forecast
Nor is PROB30. Both are laid over it
Improving doesn’t cancel
A later TEMPO or PROB30 still applies after an FM clears the sky
SCT still counts
Cloud clearance applies to any forecast cloud
Two time formats
FM carries minutes; windows and the valid period don’t
That airport isn’t your field
A TAF covers 5 statute miles around its runways
Turn in your progress
Everything this browser has saved
Your record, on one PDF. Every lesson, today’s work, and how the scenarios and the exam went. Download it and upload it where your instructor asks.
Download your progress report
The PDF carries your name and record ID. Your name is only on the PDF; on a shared computer, delete it afterward.
Check today’s plan
Your window against the limits
Three questions, kept apart. What the forecast numbers say, what the site still owes you, and the call you made.
