What should the aircraft configuration be before starting a descent on glide path during a straight-in approach?

Before beginning a descent on glide path during a straight-in approach, the correct configuration of the aircraft is to be set with landing flaps. This is essential for ensuring that the aircraft is properly configured to maintain the correct glide path and airspeed. Utilizing landing flaps allows for increased lift at lower speeds, which is critical when approaching for landing. It also helps to stabilize the aircraft's descent and allows pilots to maintain better control, particularly as they transition from the approach phase to landing.

Choosing to have the landing gear down and flaps extended or simply having flaps up and gear down does not adequately prepare the aircraft for the reduced speeds and increased lift requirements that come with final approach. Configuring with landing flaps is specifically designed to facilitate landing, while not adhering to a specific configuration can result in unoptimized performance during the critical phases of flight, potentially compromising safety and control.