Visibility, Cloud and Cumulonimbus Hazards
Visibility factors, cloud effects and the severe wind, precipitation, icing and lightning hazards associated with cumulonimbus.
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
VLOS depends on the remote pilot being able to see the aircraft well enough to control it and monitor surrounding airspace, not merely on a published visibility number.
Exam cue: Assess whether the aircraft remains continuously visible against its actual background and lighting.
Concept 2
Haze, mist, fog, low cloud, glare, darkness and a low-contrast background can reduce practical conspicuity before nominal visibility appears poor.
Exam cue: Treat a cloud or visibility change that prevents reliable orientation or airspace scanning as a stop or recovery cue.
Concept 3
Cumulonimbus clouds can produce strong updraughts and downdraughts, turbulence, hail, heavy precipitation, icing and lightning well beyond the visible core.
Exam cue: Recognise a growing cumulonimbus as a compound hazard rather than only a rain source.
Risk pitfalls and guardrails
Equating control-link telemetry or a camera view with VLOS.
Guardrail: Do not treat a certificate, automated function or minimum distance as permission to ignore current class, airspace, weather, performance or overflight restrictions.
Ignoring sun glare or background contrast because the reported visibility is high.
Guardrail: Do not treat a certificate, automated function or minimum distance as permission to ignore current class, airspace, weather, performance or overflight restrictions.
Trying to operate near a thunderstorm because the launch point is not yet raining.
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
Practical Visibility
VLOS requires enough visual detail to control the aircraft and scan surrounding airspace.
Contrast
Aircraft colour, background, glare and lighting can reduce conspicuity.
Low Cloud
Cloud can obscure the aircraft, terrain and other airspace users.
Cumulonimbus
CB clouds can bring turbulence, hail, icing, lightning and powerful vertical air movement.
Lightning
A distant-looking thunderstorm can still create electrical and wind hazards outside its rain shaft.
Recover Early
Land before deteriorating visibility or cloud removes the margin needed for a controlled recovery.
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 aircraft is a visible dot, but its orientation cannot be judged. Is VLOS still effective?
Bright sun lies directly behind the UAS. What is the safest adjustment?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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