FAA Private Pilot Airplane (PAR)Weather Theory and ServicesMedium
A pilot on final approach beneath a thunderstorm's rain shaft notices the airspeed suddenly increase and the aircraft balloon above the glidepath, followed within seconds by a rapid airspeed decrease and increasing sink rate. This sequence is most characteristic of which hazard?
- AMountain wave activity
- BA microburst
- CClear air turbulence
- DFrontal wind shift
Show answer & explanationAnswer & explanation
Correct answer: B. A microburst
A microburst produces a strong outflow that first gives an increasing headwind (airspeed gain, ballooning) as the aircraft enters the leading edge, then a rapid shift to a tailwind and downdraft as it exits, causing airspeed loss and increased sink rate. This rapid reversal within a short time and distance is the classic microburst signature.
Why the other options are wrong
- A. Mountain wave turbulence is associated with airflow over terrain, not convective outflow.
- C. Clear air turbulence occurs at altitude in clear skies, not tied to a thunderstorm's rain shaft.
- D. A frontal wind shift is a gradual synoptic-scale change, not a rapid low-altitude reversal.
Microburst
A microburst is a small-scale, intense downdraft that spreads outward upon reaching the surface, producing a rapid shift from headwind to tailwind that is extremely hazardous during takeoff or landing.
- Often associated with virga and convective activity
- Causes airspeed increase then decrease within seconds
- Can produce vertical and horizontal wind shear exceeding aircraft performance capability
Memory trick: 'Up then Down, Micro Frown' — headwind gain then tailwind loss signals a microburst.