What mode is indicated by excessive rate of descent in GPWS?

The mode indicated by an excessive rate of descent in the Ground Proximity Warning System (GPWS) is Mode 1. This mode is designed to alert pilots when the aircraft is descending too quickly, which can be indicative of a potential loss of altitude control or an impending controlled flight into terrain (CFIT) situation. When the GPWS detects that the vertical speed is excessive, it activates alerts to prompt the crew to take corrective action in order to maintain safe flight operations.

The emphasis on Mode 1 highlights the critical nature of controlling the airplane's descent, especially during approaches and landings, where maintaining proper altitude is essential for safety. By providing pilots with timely warnings, GPWS assists in preventing accidents that could arise from an excessive descent rate, ensuring better situational awareness and response capabilities.