Vref is defined as which of the following?

• A. 1.0 x stall speed
• B. 2.0 x stall speed
• C. 1.3 x stall speed
• D. 1.5 x stall speed

Answer: (C)

Vref is the reference landing speed used during final approach to ensure a safe margin above stall. It is defined as about 1.3 times the stall speed in the landing configuration (with landing flaps and gear as appropriate for the aircraft). The stall speed sets the lower limit where the aircraft would lose lift, so multiplying by 1.3 gives enough cushion to account for gusts, pilot reaction time, and the need to maintain control as you flare for landing. Because stall speed increases with weight and depends on configuration, Vref is determined for the current weight and configuration, which is why the factor 1.3 is used. The other options would place you at stall speed, or require unnecessarily high speeds not used as the standard reference for a stabilized approach.