FAA Part 107 Remote Pilot (UAG)WeatherHard
A remote pilot is monitoring a thunderstorm cell approximately 8 miles from the launch site. Which condition poses the greatest immediate hazard to a small UAS operating nearby, even though the storm itself appears to be weakening?
- AA gradual, steady increase in headwind over the next hour
- BA slow, steady crosswind that persists for several hours after the storm
- CA sudden shift from a strong headwind to a strong tailwind accompanied by a powerful downdraft, lasting only a few minutes
- DA gradual reduction in visibility caused by rising humidity levels
Show answer & explanationAnswer & explanation
Correct answer: C. A sudden shift from a strong headwind to a strong tailwind accompanied by a powerful downdraft, lasting only a few minutes
This describes a microburst, an intense, localized downdraft that spreads out at the surface, causing a rapid reversal from headwind to tailwind. Microbursts can occur even as a thunderstorm appears to be dissipating and are extremely hazardous to small, low-inertia aircraft like sUAS due to the sudden and severe wind shear.
Why the other options are wrong
- A. A gradual, predictable wind increase is manageable and not the defining hazard of thunderstorm outflow.
- B. A steady crosswind lacks the rapid onset and reversal that make microbursts so dangerous.
- D. Reduced visibility from humidity is a lesser hazard compared to the violent wind shear of a microburst.
Microburst
A microburst is a small-scale, intense downdraft from a thunderstorm that spreads outward at the surface, causing rapid and severe wind shear.
- Can occur even after a storm cell appears to weaken or dissipate
- Causes rapid shift from headwind to tailwind within seconds
- Extremely hazardous due to sudden loss of lift/performance
Memory trick: 'Micro but mighty' — a small downdraft with a massive wind-shear punch.