During an approach, what can a pilot use in the absence of a functioning glide slope?

During an approach, if a glide slope is not functioning, a pilot can rely on localizer signals as a primary means of lateral guidance. The localizer provides precise horizontal positioning information, allowing the pilot to align the aircraft with the centerline of the runway. This signal helps maintain the correct approach path in terms of lateral alignment, which is critical for a successful landing.

While visual references might assist pilots in some situations, they lack the precision that localizer guidance offers. Vertical speed indicators can provide information about the rate of descent but do not offer lateral positional guidance. Likewise, while other navigation aids can be useful, not all will provide the specific lateral alignment needed for approach and landing. The localizer is specifically designed for this purpose and is the most reliable source of guidance when the glide slope is unavailable.