Wind and Local or Urban Effects
Wind gradients, gusts, masking, funnelling and turbulence around terrain, buildings and other obstructions.
How to prepare for the CAA A2 CofC
Learn the applicable aircraft route first, then connect weather and performance limits to site planning, separation, practical drills and safe operational decisions.
Core concepts
Concept 1
Wind speed and direction can change with height, terrain and the shape of nearby buildings, so a reading at the pilot's position may not represent the aircraft's conditions.
Exam cue: Look beyond the launch point and consider the wind where the aircraft will climb, turn and return.
Concept 2
Buildings and terrain can mask wind on one side while creating accelerated, turbulent or descending flow around edges and on the lee side.
Exam cue: Treat sheltered ground-level conditions near a building as a possible masking clue rather than proof of calm air.
Concept 3
Wind limits must be assessed for the whole flight, including payload, return direction, reserve power and the possibility of gusts.
Exam cue: Compare sustained wind and gusts with the manufacturer's limit and the pilot's ability to keep the aircraft in the planned volume.
Risk pitfalls and guardrails
Assuming wind is uniform at every height and position.
Guardrail: Do not treat a certificate, automated function or minimum distance as permission to ignore current class, airspace, weather, performance or overflight restrictions.
Launching from a sheltered spot without considering turbulence above the roofline.
Guardrail: Do not treat a certificate, automated function or minimum distance as permission to ignore current class, airspace, weather, performance or overflight restrictions.
Planning an easy downwind outbound leg without preserving power for the upwind return.
Guardrail: Do not treat a certificate, automated function or minimum distance as permission to ignore current class, airspace, weather, performance or overflight restrictions.
Memory anchors
Wind Gradient
Wind commonly changes with height, so surface wind may not represent flight-level wind.
Masking
An obstacle can shelter one area while stronger flow remains above or beyond it.
Funnelling
Gaps between buildings or terrain can accelerate and redirect the wind.
Lee Turbulence
The downwind side of an obstacle may contain disturbed and descending air.
Gust Margin
Assess gusts as well as average wind against the aircraft and mission limits.
Return Reserve
Plan enough energy and control margin for the least favourable wind direction.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
The launch point is sheltered behind a warehouse. What is the main wind-planning trap?
A multirotor climbs above a row of buildings and suddenly drifts. Which effect is most likely?
Answer all questions to submit.
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Move forward only after this module is stable.
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