TAF header, validity & issuance
A TAF (Terminal Aerodrome Forecast):
- Best judgment of the most probable weather at an aerodrome, with its most probable time of occurrence
- Covers one airport, within about 5 nm of it
- Some TAFs valid 24 h (TC AIM MET 7.3)
- Read like a METAR, same order. Fields are expected, not observed
TAF CYYZ 051130Z 0512/0612 24012KT P6SM FEW040 FM051700 27015G25KT 3SM -SHRA BKN020
| Field | Example | Meaning |
|---|---|---|
| Report type | TAF |
AMD may show: amended or corrected |
| Issue time | 051130Z |
Day 05, 1130Z |
| Validity | 0512/0612 |
Format DDHH/DDHH: day + hour, not clock time. Day 05 1200Z to day 06 1200Z |
- Duration: end minus start.
0713/0723= 10 h - Valid from issue, even before stated start, until: amended, next scheduled TAF issued, or period ends
- Canadian TAF:
CAVOKnever used.RMKused, though not international code
Routine issuance:
| Item | Value |
|---|---|
| Issued | About 20 min before validity starts |
| Usual cycle | Every 6 hours (four times a day) |
| Fastest cycles | Every 3 hours at some sites |
| Maximum validity, any TAF | 30 hours |
- Issue and update cycles vary by site; see CFS (Canada Flight Supplement) for a specific aerodrome.
Trap: reading validity 0512/0612 as clock time (05:12) instead of day/hour. The 6-hour issue cycle is not the validity length, and not every site runs it.
References
- TC AIM MET 1.3.3
- TC AIM MET 3.1 Table 3.1
- TC AIM MET 7.1
- TC AIM MET 7.3