What is the purpose of a glide slope indicator?

The glide slope indicator is a critical component of the Instrument Landing System (ILS) used during an aircraft's approach for landing. Its primary purpose is to assist pilots in maintaining the correct vertical descent angle as they approach the runway. This angle is typically around 3 degrees, which is optimal for a safe landing. The glide slope indicator provides visual guidance; when the aircraft is on the correct descent path, the indicator will show that the aircraft is at the appropriate glide slope. If the indicator shows the aircraft above or below the glide slope, it alerts the pilot to make necessary adjustments to altitude and descent rate to ensure alignment with the safe approach path.

Other choices indicate functions unrelated to the glide slope. Speed information pertains to the airspeed indicator, fuel flow is monitored by fuel flow gauges, and engine performance is assessed via engine instruments. Thus, only the glide slope indicator directly addresses the need for maintaining the proper descent angle.