The relationship of the reference landing speed (VREF) to the reference stalling speed in the landing configuration (VSR0) is that VREF may not be below:

The correct relationship between reference landing speed (VREF) and reference stalling speed in the landing configuration (VSR0) is that VREF must not fall below 1.23 times VSR0. This is critical for ensuring safety during landings; VREF is designed to provide a margin above stalling speed, allowing pilots to maintain control and prevent stalls during landing maneuvers.

Having VREF set at this threshold of 1.23 VSR0 ensures that the aircraft has a significant buffer above the minimum control speed, which is especially important in the landing configuration where drag and other factors can affect the airspeed. Setting VREF at or above this level aids in stabilizing the aircraft and provides an adequate safety margin for the pilot to execute safe landings, even in the presence of variations in weight, wind gusts, and other flight conditions.

In terms of aerodynamics and aircraft performance, this guideline is fundamental for maintaining a safe and controlled landing approach, especially considering the different phases during the landing process.