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Decoding a TAF valid period group

Remote Pilot (Part 107) practice question 12 of 18 on Weather / Sources. ACS element UA.III.A.K2 · difficulty: applied. Want to answer it in a timed quiz? Use the Remote Pilot (Part 107) practice mode.

Question bank updated 2026-09-22

QUESTIONA TAF header reads TAF KPIR 111130Z 1112/1212. What valid period does the group 1112/1212 represent?

  1. A1200Z on the 11th to 1200Z on the 12th
  2. BFrom 1100Z on the 12th until 1200Z on the 12th
  3. CFrom 1112Z on the 11th until 1212Z on the 12th
Show the answer and explanation

Correct answer: A. 1200Z on the 11th to 1200Z on the 12th

  • A — correct In the valid period group the first two digits are the starting day, the next two the starting hour UTC, then the ending day and ending hour, so 1112/1212 runs from 1200Z on the 11th to 1200Z on the 12th.
  • B — incorrect This reads the digits as hour then day; the format is day then hour, so 1112 is the 11th at 1200Z.
  • C — incorrect The group contains no minutes; 1112 means day 11 at hour 12, not a clock time of 1112Z.

BACKGROUND

The TAF valid period group follows the date and time of origin. The first two digits are the day of the month for the start of the forecast, the next two digits are the starting hour in UTC, followed by a slash, the ending day, and the ending hour in UTC. A period that begins at midnight UTC is annotated as 00, and an end time at midnight UTC is annotated as 24; a 00Z TAF issued on the 9th and valid for 24 hours would show 0900/0924. The study guide's example, 1112/1212, is decoded as valid for 24 hours from 1200Z on the 11th to 1200Z on the 12th.

STUDY TIP

Read each four-digit block as day-day-hour-hour. Check your decode against the origin time: a TAF issued at 1130Z on the 11th logically begins at 1200Z on the 11th.

KEY POINTS

  • Valid period format: DDHH/DDHH in UTC.
  • 1112/1212 = 1200Z on the 11th to 1200Z on the 12th.
  • A midnight start is coded 00 and a midnight end is coded 24.

SOURCES

  • remote_pilot_study_guide.txt, Chapter 3a "Terminal Aerodrome Forecasts (TAF)", item 4 Valid period dates and times and example decode
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SkyDrill is not affiliated with the FAA. This is an original practice item based on 14 CFR part 107, 14 CFR part 89, and the FAA Remote Pilot – Small UAS Study Guide (FAA-G-8082-22). Regulations and handbooks are revised; confirm details against the current edition.