WEATHER 06 / LEARN · EXPLORE · CHECK
Weather to VFR decisions
Keep the route visual, the terrain clear, and a way out available.
Your learning goals
- Evaluate weather along the entire route at the time you will be there.
- Use cloud bases, terrain, visibility, and personal minimums together.
- Choose an early delay, diversion, or turn-around trigger.
Brief the route, not just the airports
Start with the broad weather pattern, then examine departure, climb, cruise, descent, and landing at their expected times. A clear departure and destination do not prove that the route between them is usable. Look for low cloud, fog, rain, terrain obscuration, gusts, and developing storms.
Use observations to see whether forecasts are unfolding as expected. Check updated weather before departure and during the flight. Include daylight and the return trip: familiar terrain is harder to judge at night or in haze.
Leave room for terrain and clouds
METAR cloud bases are reported above the airport, not above every hill on your route. Add airport elevation to estimate the layer’s height above sea level, then compare nearby terrain. A layer may slope or vary; one observation is only a local sample.
Apply the visibility and cloud-clearance requirements for the airspace, altitude, and day or night conditions you will actually fly in. Then add personal margin for proficiency, terrain, and forecast uncertainty. A colored weather-map dot alone does not establish that your route is legal or sensible.
A lowering ceiling is not an invitation to descend closer to obstacles. Avoid scud running: pressing on at low altitude under deteriorating cloud. Delay, turn back, or land while you still have clear terrain and a safe visual route.
Pick the exit before you need it
Identify suitable landing options along the route and check their weather, runways, wind, fuel availability, and operating status. Choose options with different weather exposure; two airports under the same fog bank may both become unusable.
Set specific triggers before takeoff: a ceiling or visibility below your personal minimum, storms growing toward the route, increasing gusts, or a fuel/time point that requires a diversion. Account for headwinds, deviations, and the fuel needed to land with the required reserve and your extra margin. Do not spend that margin hoping the weather improves.
A delay can be the successful decision
Compare three choices: go as planned, change the route or time, or stay on the ground. The right choice can change as the weather develops. Passenger expectations and a schedule do not improve visibility or aircraft performance.
If the visual route starts closing, act before options disappear. Turn back or divert while conditions still allow it, and ask ATC or Flight Service for help early. Use your training and the aircraft’s procedures if you inadvertently lose outside visual references; treat it as an emergency requiring prompt assistance.
FLIGHT SCENARIO
What would change your plan?
Your destination is clear, but reports near a ridge show a lowering cloud layer and rain. Continuing would require flying progressively lower to stay beneath it. A suitable airport behind you remains clear. What is the useful decision now?
- NoticeWhat does this situation require?
- VerifyWhat evidence is still missing?
- DecideWhat keeps an option open?
Compare your reasoning
Turn back or divert while the route to clear weather is still open. Check terrain, cloud bases, visibility, wind, and fuel. A clear destination does not make the intervening ridge safe, and descending to squeeze beneath the cloud spends your terrain margin.
SUMMARY
Turn around while you still have options.
Turn back or divert while the route to clear weather is still open. Check terrain, cloud bases, visibility, wind, and fuel. A clear destination does not make the intervening ridge safe, and descending to squeeze beneath the cloud spends your terrain margin.
Before moving on, explain the decision in your own words: what would you verify, and what would make you change the plan?
PRACTICE
Flashcards and knowledge check
Six flashcards, then five questions with explanations.
Enable JavaScript for flashcards and the knowledge check. The lesson and scenario remain available without it.
Sources & lesson notes
Sources & lesson notes
- FAA Aviation Weather HandbookAtmospheric processes, clouds, fronts, hazards, and aviation weather products.
- NOAA Aviation Weather Center: product guideReport formats, forecast coverage, and advisory definitions.
- FAA AIM: MeteorologyBriefing, datalink limitations, and weather avoidance guidance.
Curriculum framework: the supplied Weather Theory and weather products documents. All scenarios are educational examples, not current weather. Content reviewed September 2026.