<P> The most common V - speeds are often defined by a particular government's aviation regulations . In the United States, these are defined in title 14 of the United States Code of Federal Regulations, known as the Federal Aviation Regulations (FARs). In Canada, the regulatory body, Transport Canada, defines 26 commonly used V - speeds in their Aeronautical Information Manual . V - speed definitions in FAR 23, 25 and equivalent are for designing and certification of airplanes, not for their operational use . The descriptions below are for use by pilots . </P> <P> These V - speeds are defined by regulations . They are typically defined with constraints such as weight, configuration, or phases of flight, some of these constraints have been omitted to simplify the description . </P> <Table> <Tr> <Th> V - speed designator </Th> <Th> Description </Th> </Tr> <Tr> <Td> V </Td> <Td> The speed beyond which the takeoff should no longer be aborted . (See V definitions below) </Td> </Tr> <Tr> <Td> V </Td> <Td> Takeoff safety speed . The speed at which the aircraft may safely be climbed with one engine inoperative . </Td> </Tr> <Tr> <Td> V </Td> <Td> Minimum takeoff safety speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Flap retraction speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Steady initial climb speed . The all engines operating take - off climb speed used to the point where acceleration to flap retraction speed is initiated . Should be attained by a gross height of 400 ft (120 m). </Td> </Tr> <Tr> <Td> V </Td> <Td> Design maneuvering speed . This is the speed above which it is unwise to make full application of any single flight control (or "pull to the stops") as it may generate a force greater than the aircraft's structural limitations . </Td> </Tr> <Tr> <Td> V </Td> <Td> Indicated airspeed at threshold, which is usually equal to the stall speed V multiplied by 1.3 or stall speed V multiplied by 1.23 in the landing configuration at the maximum certificated landing mass, though some manufacturers apply different criteria . If both V and V are available, the higher resulting V shall be applied . Also called "approach speed". </Td> </Tr> <Tr> <Td> V </Td> <Td> Design speed for maximum gust intensity . </Td> </Tr> <Tr> <Td> V </Td> <Td> Design cruise speed, used to show compliance with gust intensity loading . </Td> </Tr> <Tr> <Td> V </Td> <Td> See V; generally used in documentation of military aircraft performance . Denotes "critical engine failure" speed as the speed during takeoff where the same distance would be required to either continue the takeoff or abort to a stop . </Td> </Tr> <Tr> <Td> V </Td> <Td> Design diving speed, the highest speed planned to be achieved in testing . </Td> </Tr> <Tr> <Td> V </Td> <Td> Demonstrated flight diving speed, the highest actual speed achieved in testing . </Td> </Tr> <Tr> <Td> V </Td> <Td> The speed at which the critical engine is assumed to fail during takeoff . </Td> </Tr> <Tr> <Td> V </Td> <Td> Designed flap speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Maximum speed for stability characteristics . </Td> </Tr> <Tr> <Td> V </Td> <Td> Maximum flap extended speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Final takeoff speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Maximum speed in level flight at maximum continuous power . </Td> </Tr> <Tr> <Td> V </Td> <Td> Maximum landing gear extended speed . This is the maximum speed at which a retractable gear aircraft should be flown with the landing gear extended . </Td> </Tr> <Tr> <Td> V </Td> <Td> Maximum landing gear operating speed . This is the maximum speed at which the landing gear on a retractable gear aircraft should be extended or retracted . </Td> </Tr> <Tr> <Td> V </Td> <Td> Lift - off speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Minimum control speed . The minimum speed at which the aircraft is still controllable with the critical engine inoperative . Like the stall speed, there are several important variables that are used in this determination . Refer to the minimum control speed article for a thorough explanation . V is sometimes further refined into more discrete V - speeds e.g. V, V . </Td> </Tr> <Tr> <Td> V </Td> <Td> Minimum control speed air . The minimum speed that the aircraft is still controllable with the critical engine inoperative while the aircraft is airborne . V is sometimes simply referred to as V . </Td> </Tr> <Tr> <Td> V </Td> <Td> Minimum control speed ground . The minimum speed that the aircraft is still controllable with the critical engine inoperative while the aircraft is on the ground . </Td> </Tr> <Tr> <Td> V </Td> <Td> Minimum control speed in the landing configuration with one engine inoperative . </Td> </Tr> <Tr> <Td> V </Td> <Td> Maximum operating limit speed . Exceeding V may trigger an overspeed alarm . </Td> </Tr> <Tr> <Td> V </Td> <Td> Minimum unstick speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Never exceed speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Maximum structural cruising speed or maximum speed for normal operations . </Td> </Tr> <Tr> <Td> V </Td> <Td> Maximum operating maneuvering speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Rotation speed . The speed at which the pilot begins to apply control inputs to cause the aircraft nose to pitch up, after which it will leave the ground . </Td> </Tr> <Tr> <Td> V </Td> <Td> Used instead of V (in discussions of the takeoff performance of military aircraft) to denote rotation speed in conjunction with the term V (refusal speed). </Td> </Tr> <Tr> <Td> V </Td> <Td> Landing reference speed or threshold crossing speed . <P> (In discussions of the takeoff performance of military aircraft, the term V stands for refusal speed . Refusal speed is the maximum speed during takeoff from which the air vehicle can stop within the available remaining runway length for a specified altitude, weight, and configuration .) Incorrectly, or as an abbreviation, some documentation refers to V and / or V speeds as "V ." </P> </Td> </Tr> <Tr> <Td> V </Td> <Td> Stall speed or minimum steady flight speed for which the aircraft is still controllable . </Td> </Tr> <Tr> <Td> V </Td> <Td> Stall speed or minimum flight speed in landing configuration . </Td> </Tr> <Tr> <Td> V </Td> <Td> Stall speed or minimum steady flight speed for which the aircraft is still controllable in a specific configuration . </Td> </Tr> <Tr> <Td> V </Td> <Td> Reference stall speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Reference stall speed in landing configuration . </Td> </Tr> <Tr> <Td> V </Td> <Td> Reference stall speed in a specific configuration . </Td> </Tr> <Tr> <Td> V </Td> <Td> Speed at which the stall warning will occur . </Td> </Tr> <Tr> <Td> V </Td> <Td> Category A rotorcraft takeoff safety speed . </Td> </Tr> <Tr> <Td> V </Td> <Td> Speed that will allow for best angle of climb . </Td> </Tr> <Tr> <Td> V </Td> <Td> Speed that will allow for the best rate of climb . </Td> </Tr> </Table> <Tr> <Th> V - speed designator </Th> <Th> Description </Th> </Tr>

What does v1 and v2 mean in aviation
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