P-static is best described as which phenomenon?

• A. A form of radio interference caused by rain, snow, or dust particles hitting the antenna and inducing a small radio-frequency voltage into it.
• B. Static electricity on the airframe due to friction.
• C. Power fluctuations in the generator.
• D. Grounding faults in avionics.

Answer: (A)

Precipitation static is the buildup of static electricity on the aircraft caused by precipitation particles—rain, snow, or dust—striking the airframe as the plane moves. This charging and subsequent discharge into the antenna creates a small RF voltage, which shows up as crackling or static on the radio and navigation receivers. The effect is most noticeable in precipitation conditions and is what pilots experience as intermittent noise on comms and nav aids.

Static on the airframe from friction is a different, more general type of static not tied to precipitation specifically. Power fluctuations in the generator and grounding faults in avionics describe other electrical issues that don’t cause the characteristic precipitation-related RF noise. Static wicks and proper bonding help dissipate charges to reduce P-static effects.