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Recognizing precipitation static symptoms

Remote Pilot (Part 107) practice question 33 of 36 on Airspace / Operational Requirements. ACS element UA.II.B.K4d · difficulty: standard. Want to answer it in a timed quiz? Use the Remote Pilot (Part 107) practice mode.

Question bank updated 2026-09-22

QUESTIONWhile flying through snow, a pilot hears a high pitched squeal in the headphones, loses VHF communications, and sees the magnetic compass give erroneous readings. These symptoms are typical of

  1. Acarburetor icing forming in the induction system.
  2. Ba failure of the aircraft's transponder antenna.
  3. Cprecipitation static building on the airframe.
Show the answer and explanation

Correct answer: C. precipitation static building on the airframe.

  • A — incorrect Induction icing affects engine operation, not avionics and compass indications. Nothing in the precipitation static discussion attributes radio squeal or compass error to icing in the induction system.
  • B — incorrect A single antenna failure would not produce audio squeal, loss of VHF communications and compass errors at the same time. The combined symptom set is the signature of a static charge on the airframe.
  • C — correct A high pitched squeal on audio, complete loss of VHF communications and erroneous magnetic compass readings are all listed as symptoms caused by precipitation static, which builds as the aircraft strikes uncharged particles such as snow.

BACKGROUND

Precipitation static, usually shortened to P-static, is caused by an aircraft in flight coming into contact with uncharged particles such as rain, snow, fog, sleet, hail, volcanic ash or dust. When the aircraft strikes these neutral particles, the negative part of the particle adheres to the skin of the aircraft and a substantial negative charge develops in a very short time. If the aircraft has no static dischargers, or has an ineffective system, the aircraft may go into corona and discharge static electricity from its extremities such as wing tips, stabilizers, antennas and propeller tips. Pilot reports of P-static include complete loss of VHF communications, magnetic compass readings as much as thirty percent in error, a high pitched squeal or a motor boat sound on audio, erratic instrument readouts, weak transmissions, and St. Elmo's Fire on the windshield. The only correction is the proper number of quality static dischargers, properly installed on a properly bonded aircraft.

STUDY TIP

Link the symptom list to one cause: radio noise plus compass error in precipitation means static charge, not an instrument failure. Also remember that static dischargers, not pilot technique, are the fix.

KEY POINTS

  • P-static builds when an aircraft strikes uncharged particles such as rain, snow, hail, ash or dust.
  • Symptoms include loss of VHF communications, audio squeal, erroneous compass readings and St. Elmo's Fire.
  • Properly installed static dischargers on a properly bonded aircraft are the only correction.

SOURCES

  • AIM 7-6-12 "Precipitation Static"
  • sources/aim/aim_7-6_potential_flight_hazards.txt
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SkyDrill is not affiliated with the FAA. This is an original practice item based on 14 CFR part 107, 14 CFR part 89, and the FAA Remote Pilot – Small UAS Study Guide (FAA-G-8082-22). Regulations and handbooks are revised; confirm details against the current edition.