Let me go through them in the order they appear — Page 537, Lesson 659

This is the index of the book — the alphabetical listing of every speed definition used throughout the performance chapters. So what I want to walk you through is the meaning of each of these V-speeds, because they are the vocabulary of take-off and landing performance. Let me go through them in the order they appear. First, V2 — Take-off Safety Speed, referenced on page 257. This is the speed at which the aircraft can safely climb after an engine failure, with one engine inoperative, and still meet the required climb gradient. It's the speed you rotate to and hold during the initial climb segment. Next, V3 — this is the speed at which the aircraft can safely climb with one engine inoperative, but it's used later in the take-off path, after the acceleration segment. It's the speed for the second segment of climb. Then V4 — this is the steady climb speed used during the take-off path, typically after the flaps are retracted, and it's the speed you maintain for the remaining climb segments. Now, Variable Pitch Propellers — this is a propeller system where the blade angle can be changed in flight, allowing the engine to operate at its most efficient RPM regardless of airspeed. It's not a speed itself, but it's listed here because it affects performance. Variations of Take-off Thrust with Air Temperature — this is a relationship, not a speed. It shows how the thrust available at take-off changes as the outside air temperature changes. Hotter air is less dense, so thrust decreases; colder air is denser, so thrust increases. Now the critical ones. VEF — this is the speed at which the critical engine is assumed to fail during the take-off. It's the speed used in the take-off distance calculations, and it's referenced on pages 10, 15, and 250. VFE — this is the maximum flap extended speed. It's the highest speed at which you may fly with flaps in a given extended position, and exceeding it could damage the flaps. VFTO — this is the final take-off speed, the speed you aim for at the end of the take-off path, typically at the screen height. VGO — this is the go-around speed, the speed you use if you abort the landing and go around for another approach. It's referenced on pages 15 and 250. Viscous Hydroplaning — this is a type of hydroplaning where a thin film of water, oil, or rubber residue on the runway prevents tire contact with the pavement, even at relatively low speeds. It's referenced on page 160. VLE — this is the maximum landing gear extended speed, the highest speed at which you may fly with the landing gear extended. VLO — this is the maximum landing gear operating speed, the highest speed at which you may extend or retract the landing gear. VLOF — this is the lift-off speed, the speed at which the aircraft first becomes airborne. It's referenced on page 256. VMBE — this is the maximum brake energy speed, referenced on page 252. This is the speed at which, if you abort the take-off, the brakes will absorb the maximum energy they can handle without overheating or failing. Exceeding it means the brakes may not be able to stop the aircraft safely. VMC — this is the minimum control speed, referenced on page 15. It's the minimum speed at which the aircraft can be controlled in the air with one engine inoperative. VMCA — this is the air minimum control speed, also on page 15. It's the minimum speed at which the aircraft can be controlled in the air with the critical engine inoperative, and it's the same as VMC in most contexts. VMCA / VMC — Air Minimum Control Speed — this is the full definition, referenced on page 254. It's the minimum speed at which directional control can be maintained with the critical engine inoperative, with the aircraft in the air. VMCG — this is the ground minimum control speed, referenced on pages 15 and 249. It's the minimum speed at which the aircraft can be controlled on the ground with the critical engine inoperative, using rudder and nosewheel steering, while keeping the aircraft on the runway centerline. VMCL — this is the landing minimum control speed, referenced on page 15. It's the minimum speed at which the aircraft can be controlled during landing with one engine inoperative. VMD — this is the minimum drag speed, referenced on page 15. It's the speed at which the aircraft's total drag is at its lowest, which is also the speed for best glide and maximum endurance. VMO — this is the maximum operating speed, referenced on page 15. It's the maximum speed at which the aircraft may be flown in normal operations, and exceeding it could cause structural damage. VMP — this is the minimum power speed, referenced on page 15. It's the speed at which the aircraft requires the least power to maintain level flight, which is the speed for maximum range. VMU — this is the minimum unstick speed, referenced on page 15. It's the minimum speed at which the aircraft can be rotated and lifted off the ground without the tail striking the runway. So that's the full set of V-speeds from this index. Each one defines a specific operational limit or performance point, and together they govern every phase of take-off, climb, cruise, and landing.