Performance calculations assume the threshold is crossed at:

Performance calculations assume the threshold is crossed at:

• A. 40 ft; V2
• B. 50 ft; Vref
• C. 60 ft; Vapp
• D. 25 ft; Vref

Answer: (B)

Landing performance calculations are based on a standardized moment when you cross the threshold at fifty feet above the runway while running at the reference landing speed. Fifty feet is the fixed threshold-crossing height used in performance data, reflecting a typical stabilized approach near the runway. Vref is the reference landing speed chosen for the weight and configuration, representing the safe touchdown energy level for calculating stopping distance and required runway length. This pairing keeps the data consistent across conditions. Other options mix in speeds associated with takeoff (like V2) or with different approach speeds (like Vapp), which aren’t the standard threshold-crossing assumptions for landing performance.

Landing performance calculations are based on a standardized moment when you cross the threshold at fifty feet above the runway while running at the reference landing speed. Fifty feet is the fixed threshold-crossing height used in performance data, reflecting a typical stabilized approach near the runway. Vref is the reference landing speed chosen for the weight and configuration, representing the safe touchdown energy level for calculating stopping distance and required runway length. This pairing keeps the data consistent across conditions. Other options mix in speeds associated with takeoff (like V2) or with different approach speeds (like Vapp), which aren’t the standard threshold-crossing assumptions for landing performance.