Final answer:
The LND FLAP 3 pushbutton on the GPWS PANEL is used to control the configuration of the flaps during landing in aviation.
Step-by-step explanation:
The LND FLAP 3 pushbutton on the GPWS PANEL is used in aviation and stands for Landing Flap 3. It is a control button that controls the configuration of the aircraft's flaps during landing. Flaps are movable surfaces on the wings of an aircraft that increase lift and drag, allowing for slower speeds and steeper descent angles during landing. By selecting the LND FLAP 3 pushbutton, the pilot sets the flap position to 3, indicating the desired degree of extension for the flaps during landing.
The LDG Flap 3 pushbutton will still warn you should you intend on landing in flap 3 (common these days for fuel saving) but you have flaps 1 or 2 selected only. The LDG Flap pushbutton is more useful in cases of Flap / Slat Jams and other computer failures that result in landing with a reduced flap / slat setting.