During an ILS approach, what should a pilot do if the localizer signal is lost?

When a pilot loses the localizer signal during an Instrument Landing System (ILS) approach, the most prudent action would be to abort the approach immediately. The localizer provides lateral guidance to the runway, and its loss means that the pilot no longer has a reliable reference for aligning the aircraft with the runway. This loss can lead to uncertainty about the aircraft's position relative to the runway, increasing the risk of an unsafe landing.

Aborting the approach allows the pilot to regain control and reassess the situation, ensuring that they can safely land the aircraft, whether by attempting a go-around and trying the approach again or by safely diverting to an alternate airport if conditions permit. This course of action emphasizes safety and prioritizes maintaining control of the aircraft when critical navigational information is no longer available.