Significant weather detection
121.  An AOC holder must ensure that every relevant aircraft that is used to carry passengers and is not a non‑pressurised aeroplane is equipped with an operative weather radar or other equipment capable of detecting thunderstorms or other potentially hazardous weather conditions whenever the aircraft is to be or is being operated —
(a)in areas where such conditions may be expected to exist along the route in instrument meteorological conditions; or
(b)at night.