What is the single-engine approach speed on a Precision Approach Radar (PAR)?

The single-engine approach speed during a Precision Approach Radar (PAR) is typically based on a specific formula that reflects the aircraft's required performance during approach with one engine inoperative. In this context, VAPP equates to VREF plus an additional value to ensure safe control of the aircraft during the approach phase. Generally, for a single-engine configuration, VAPP is calculated as VREF plus a margin for safety that accounts for the reduced performance and handling characteristics of the aircraft.

Adding 10 knots to VREF is a widely accepted practice because this provides an adequate buffer to maintain control of the aircraft while enabling necessary responsiveness to any adjustments that may be required in the approach. This choice balances the need for a safe and manageable approach speed while maintaining efficiency and adherence to operational safety standards.