The Preflight Weather Briefing: A Checklist That Works
The mistake in a weak briefing is almost never a missing product. It is the order. People open the destination METAR first, form an impression, and then read everything else as confirmation of the impression they already have.
A briefing works outward-in: the synoptic picture first, then the route, then the aerodromes, then the warnings that cut across all of it. Doing it in that order means the aerodrome reports arrive as detail on a picture you already understand, rather than as a picture you build from one report.
The order, and why it is that order#
- The synoptic picture. Where are the fronts, the lows and the jet? What is moving, and how fast? This sets expectations for everything else.
- The route. Significant weather charts and upper winds at your levels. Icing and turbulence areas, convection, and the fuel implication of the wind.
- The destination. TAF first, for the window around arrival plus realistic holding. METAR second, to see how the forecast is verifying.
- The alternate. Its own TAF, read against the higher alternate planning minima, and far enough away to be under different weather.
- The departure aerodrome. METAR and TAF for the departure window, plus de-icing and runway condition in winter.
- The warnings. SIGMET, AIRMET, volcanic ash and tropical cyclone advisories across the whole route.
- NOTAMs. Not weather, but they decide whether the approach you are planning against actually exists today.
Step three before step five is deliberate. The question that decides whether the flight is viable is at the destination, and reading the departure first is how people talk themselves into starting.
How the TAF is verifying#
One check separates a competent briefing from a thorough one: compare the current METAR against what the TAF said for this hour. If the forecast is verifying well, you can lean on the rest of it. If conditions are already worse than forecast at this point, the later part of the TAF is suspect and an amendment is probably coming.
- Forecast conditions matching observation — the TAF is tracking; trust the later groups.
- Observed worse than forecast — the deterioration is early; expect an amendment and plan pessimistically.
- Observed better than forecast — pleasant, but do not plan on it continuing; forecasters are deliberately conservative.
- A TAF issued several hours ago with rapidly changing conditions — check for an AMD before anything else.
This check takes fifteen seconds and it is the single highest-value item in the whole sequence.
The freezing level and the cloud tops#
Two derived numbers do most of the work on the route and neither appears directly in a METAR. The freezing level tells you where the icing band starts and whether your climb or descent passes through it inside cloud. The cloud tops tell you whether you can be on top, and therefore whether the ride and the icing exposure change with a level request.
| Question | Where to find it |
|---|---|
| Where is the freezing level? | Upper wind and temperature data, significant weather chart |
| Am I in cloud through the icing band? | Cloud layers from the TAF and the area forecast |
| What are the tops? | Area forecast, satellite imagery, pilot reports |
| Will the wind cost or save fuel? | Upper wind charts at planned levels |
| Where is the jet, and the shear beside it? | Upper wind chart; CAT areas on the significant weather chart |
The checks people skip#
- The alternate’s own TAF. Nominating an alternate without reading it is common and pointless.
- The trend group. A METAR at the limit with a BECMG improving is a different flight from one with NOSIG.
- Amendments. A TAF read an hour ago may have been replaced twice, and amendments cluster when things are deteriorating.
- Sunset and sunrise times. Weather that is workable in daylight can be a different proposition at night, and night VFR rules differ by state.
- Runway condition and braking action in winter, which changes the landing distance required more than the ceiling does.
- The return. For a same-day return, the destination’s later forecast matters as much as the arrival one.
None of these is obscure. They get skipped because the briefing felt finished after the destination METAR looked acceptable.
Writing it down#
A briefing that exists only in your head cannot be compared with reality later, and comparison is how judgement is built. A short written record — the numbers you decided against, the alternate you chose and why, the item you were unsure about — turns each flight into evidence about how you read weather.
- Note the destination and alternate ceilings and visibilities you planned against.
- Note the worst TEMPO or PROB value you accepted, and why it was acceptable.
- Note the fuel decision and what drove it.
- Note the one thing you were least sure about.
- After the flight, write what actually happened in a single line.
Do this for twenty flights and the pattern in your own misjudgements becomes obvious, which is not something any amount of reading will give you.
What a briefing cannot do#
It cannot make the decision. Everything above produces a picture; the go or no-go rests with the pilot in command, against the operator’s minimums, the aircraft’s equipment and limitations, and an honest assessment of recency and fatigue. A thorough briefing that ends in a decision to stay on the ground is a successful briefing.
And it has to be an official one. Explanatory sites — including this one — are for understanding what the products mean, never for obtaining them.
Frequently asked questions
What should a preflight weather briefing include?
Seven things, in order: the synoptic picture, the route weather and upper winds, the destination TAF and METAR, the alternate’s own TAF, the departure aerodrome, the warnings — SIGMET, AIRMET, volcanic ash and cyclone advisories — and finally NOTAMs. The order matters as much as the contents: working outward-in means the aerodrome reports arrive as detail on a picture you already understand rather than as an impression you then confirm.
How long before a flight should I check the weather?
In layers. A first look the day before establishes what kind of day it will be and whether the trip is realistic. A full briefing goes in the last few hours, when TAFs covering your window are current. A final check immediately before departure catches amendments, which are issued precisely when conditions are deteriorating and are the most common thing to be caught out by. For a longer flight, the destination forecast should be rechecked en route where that is possible.
What is the most commonly skipped item in a weather briefing?
The alternate’s own TAF. An alternate is nominated, the fuel is carried, and nobody reads the forecast for the place — which defeats the purpose, since an alternate under the same weather system as the destination is not an alternate. Close behind it are the trend group on a marginal METAR, and checking for an amended TAF before departure. All three take under a minute and all three change decisions.
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