If the localizer mode is armed, what is the necessary course accuracy for satisfactory mode capture?

When the localizer mode is armed, the necessary course accuracy required for satisfactory mode capture is indeed 5 degrees. This specification is crucial because the localizer provides lateral guidance to the runway centerline during an approach. To ensure successful capture of the localizer signal, the aircraft must be within a narrow range of angular deviation from the course.

A deviation greater than 5 degrees can lead to difficulties in capturing the localizer signal effectively, which could affect the precision of the approach and could potentially result in a missed approach if not rectified. This level of accuracy is part of the safety protocols established for precision approaches, ensuring that pilots maintain the necessary control over the aircraft's lateral positioning in relation to the intended flight path leading to the runway.

Understanding this critical requirement aids pilots in executing safe and accurate landings, maintaining adherence to operational standards within the approach environment.