Which GPWS mode provides warnings of excessive deviation below the glide path with landing gear extended?

Mode 5 of the Ground Proximity Warning System (GPWS) is specifically designed to provide warnings related to excessive deviation below the glide path when the landing gear is extended. This mode is particularly important for ensuring that aircraft maintain the appropriate descent profile during the approach phase of landing.

In practice, the activation of Mode 5 occurs when the aircraft's altitude is lower than the designated glide path, which can be critical for preventing controlled flight into terrain (CFIT) situations. By alerting pilots of these deviations, Mode 5 enhances safety during the landing process, ensuring that they can take corrective action to align with the glide path and land safely.

The other modes of GPWS, while also essential, focus on different aspects of terrain awareness and approach safety. For instance, some modes respond to abrupt altitude changes or provide warnings when an aircraft is dangerously close to the ground without an appropriate context like gear configuration. However, only Mode 5 directly addresses the situation of being excessively below the glide path with the landing gear down.