Vref

Vref is the landing reference speed - the base speed from which the final approach speed (VAPP) is derived. It is defined as 1.23 times the 1g stall speed (VS1G) in the landing configuration at the aircraft’s landing weight. This 23% margin above the stall speed provides adequate buffet margin, gust resistance, and handling safety during the critical approach and flare phases. Vref decreases as landing weight decreases, so a lighter aircraft will have a lower Vref and can fly a slower, more energy-efficient approach. Vref is published in the aircraft’s Quick Reference Handbook (QRH) or performance charts as a function of landing weight and flap setting. On most modern aircraft, Vref is calculated automatically by the FMS once the landing weight and flap configuration are entered. VAPP is then derived from Vref by adding wind and gust corrections per the airline’s standard operating procedures - typically Vref plus half the steady headwind component plus the full gust increment, capped at a defined maximum. The threshold crossing speed target is generally Vref or VAPP (depending on operator procedure), and the aircraft should be stabilised at this speed by the final approach gate. At touchdown, the speed should be close to Vref, with the idle thrust and flare consuming the additive margin accumulated on approach.

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In Virtual Airline Operations

Most high-fidelity aircraft add-ons used by VACA virtual pilots will compute Vref automatically from the landing weight input in the MCDU or flight computer. Virtual pilots should verify the computed Vref against published performance tables where possible and use it as the baseline for setting VAPP. Landing consistently at or near Vref - rather than significantly fast or slow - is a key indicator of approach quality and contributes to realistic flight performance scores.

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Related Terms

• VAPP - Approach Speed
• ZFW - Zero Fuel Weight
• TOD - Top of Descent