What is Vref for landing configuration on the CRJ 900?

Vref, or reference landing speed, for the CRJ 900 is indeed variable based on weight and configuration. This speed is essential for ensuring that the aircraft is flown at an appropriate velocity when crossing the runway threshold, and it directly relates to the aircraft's weight at the time of landing along with its flap configuration.

As the aircraft's weight changes, Vref also adjusts because the amount of lift required changes; a heavier aircraft necessitates a higher speed to maintain the same aerodynamic performance. Additionally, different flap settings alter the aircraft's lift characteristics, further influencing the Vref. This adaptability helps pilots achieve safe landings under various conditions and ensures that they are operating within the specified performance guidelines for the aircraft.

In contrast, the other options suggest that Vref is a static number or determined by a procedure that does not take into account the dynamic operation characteristics of the aircraft, which is not accurate for safe and effective flight operations.