Airborne thunderstorm detection equipment requirements

This regulation requires larger aircraft operating under Part 135 to carry thunderstorm detection equipment in certain situations.

Aircraft with 10 or more passenger seats must have approved thunderstorm detection equipment or weather radar when carrying passengers, except helicopters operating in day VFR conditions. Helicopters with 10+ passenger seats need this equipment for night VFR operations when thunderstorms are reasonably expected along the route.

Before departing IFR or night VFR when thunderstorms are forecast, the required equipment must be working properly. If it fails during flight, you must follow procedures in your operations manual.

The rule doesn't apply to operations solely within Hawaii, Alaska, or northwestern Canada (west of 130°W, between 53°N and 70°N), nor to training, test, or ferry flights. Unlike most aircraft equipment, thunderstorm detection systems don't require a backup electrical power supply.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*