V-speeds are named airspeed limits or performance references. They are not divided into airspeed and engine-power categories. Their exact values come from the aircraft’s approved flight manual or pilot’s operating handbook and may change with weight, altitude, configuration or other specified conditions.
Limits you may see on an airspeed indicator
VNE is the never-exceed speed. VNO is the maximum structural cruising speed; operations above it are restricted to the conditions described in the aircraft handbook, rather than being a normal cruise target. VFE is the maximum flap-extended speed, sometimes with different limits for different flap settings.
VA, the design maneuvering speed, deserves particular attention. Its meaning and permitted control inputs are often oversimplified. It does not protect against every combination of abrupt inputs or turbulence, and its value generally varies with weight. Use the handbook’s limitations and operating guidance.
Stall and climb references
VS refers to the stalling speed or minimum steady flight speed in a specified configuration. VSO is the corresponding landing-configuration reference. A stall is caused by exceeding the critical angle of attack; these published speeds do not mean an aircraft cannot stall at a higher airspeed during a maneuver.
VX gives the best angle of climb under stated conditions, useful for gaining altitude over distance. VY gives the best rate of climb, useful for gaining altitude over time. Neither is an engine power setting.
Transport-aircraft references
Airline crews also work with takeoff and landing references such as V1, VR, V2 and VREF. They are calculated or selected using aircraft procedures and performance data for the flight. A simple slogan such as ‘the point of no return’ does not fully describe a takeoff decision speed.
Learn the aircraft, not just the abbreviations
Before flying, establish which values are fixed, which must be calculated and which conditions apply. Check the handbook rather than borrowing numbers from a similar-looking airplane. The FAA’s Pilot’s Handbook of Aeronautical Knowledge provides the general background; approved aircraft documents provide the operating values.