It’s a certification limit, not a normal operating speed — Page 537, Lesson 660

This is the index of the book — the alphabetical list of every topic, term, and speed definition we’ll be covering. I want to walk you through the entries that matter most for your professional training, because this index is your map of the whole syllabus. Let’s start with the V speeds, because those are the backbone of performance work. VMU is the Minimum Unstick Speed — that’s the lowest speed at which the aeroplane can safely leave the ground and continue the take-off, even if you rotate aggressively. It’s a certification limit, not a normal operating speed. VR is the Rotation Speed — the speed at which you actually pull back on the control column to raise the nose and lift off. Notice the distinction: VMU is the physical minimum, VR is the operational choice, and VR must always be at least VMU. Then we have the stall-based speeds. VS is the stalling speed, the basic one. VS0 is the stalling speed in the landing configuration — flaps down, gear down. VS1 is the stalling speed in a specific configuration, usually the clean or cruise configuration. VSR is the reference stalling speed, and VSR0 is the reference stalling speed in the landing configuration — these are the certified reference values used in performance calculations, not the actual measured stall. VNE is the Never Exceed Speed — the red line, the absolute maximum speed you must never go beyond. VP is the maximum speed for the propeller, if you’re flying a propeller-driven aircraft. VRA is the rough air speed — the maximum speed you can fly in turbulent conditions without overstressing the structure. VREF is the reference landing speed, the target speed you fly on final approach. VSTOP is the speed at which you can stop — the maximum speed from which you can abort and bring the aircraft to a halt within the remaining runway. VX is the best angle of climb speed — that gives you the greatest height gain per unit of horizontal distance. VY is the best rate of climb speed — that gives you the greatest height gain per unit of time. Now the W section. WAT is the Weight, Altitude, Temperature limit — that’s the combined structural and performance limit on take-off mass. Weight on Climb Angle and Weight or Bank Angle on Drag are the performance relationships we’ll study — how weight affects your climb gradient, and how weight or bank angle changes the drag you have to overcome. Wet Runway and Wet Runways are the degraded braking conditions — a wet surface reduces friction and extends your landing distance. Wheel and Brake Drag and Wheel Drag are the drag contributions from the landing gear and the brakes during the ground roll. Wind and Windshear are the atmospheric effects — wind changes your ground performance, and windshear is a sudden change in wind that can threaten your climb or approach. In the Y section, Yaw is the rotation about the vertical axis — the nose swinging left or right. And in the Z section, Zero Flap Speed is the maximum speed at which you can fly with the flaps fully retracted. ZFW/ZFM is Zero Fuel Weight and Zero Fuel Mass — the weight of the aircraft with all payload and fuel loaded, but before you add the fuel itself; it’s a structural limit on the fuselage. Now, I want you to notice the page numbers — VMU is on page 254, VR is on page 254, V Speeds as a topic is on page 249. That tells you the V speed definitions are grouped together in the performance chapter, and we’ll get to them in detail. The index is your navigation tool — when you’re studying, you use it to jump straight to the definition you need. Those three figures — the field limit mass, the take-off climb limit mass, and the tyre speed limit mass — are the graphical representations of the limits we just named. Field limit mass is the maximum take-off mass allowed by the runway length available. Take-off climb limit mass is the maximum mass at which you can still meet the climb gradient requirements after an engine failure. Tyre speed limit mass is the maximum mass at which your tyre speed stays below its certified limit during the take-off roll. Those are the three big take-off mass limits you’ll balance against each other. That’s the index — it’s your roadmap. Every term we just named is a chapter we’ll work through together.