V$_{Y}$.  Best rate-of-climb speed. This airspeed provides the most  altitude gain in a given period of time.  G-19 Vertical stability.  Stability about an aircraft’s vertical axis.  Also called yawing or directional stability.  V$_{MO}$.  Maximum operating speed expressed in knots.  V$_{NE}$.  Never-exceed speed. Operating above this speed is  prohibited since it may result in damage or structural failure.  The red line on the airspeed indicator.  V$_{FE}$.  The maximum speed with the flaps extended. The upper  limit of the white arc.  V$_{FO}$.  The maximum speed that the flaps can be extended or  retracted.  V$_{NO}$.  Maximum structural cruising speed. Do not exceed this  speed except in smooth air. The upper limit of the green arc.  V$_{P}$.  Minimum dynamic hydroplaning speed. The minimum  speed required to start dynamic hydroplaning.  VFR Terminal Area Charts (1:250,000).  Depict Class B  airspace which provides for the control or segregation of all  the aircraft within the Class B airspace. The chart depicts  topographic information and aeronautical information  which includes visual and radio aids to navigation, airports,  controlled airspace, restricted areas, obstructions, and related  data.  V$_{R}$.  Rotation speed. The speed that the pilot begins rotating  the aircraft prior to lift-off.  V$_{S0}$.  Stalling speed or the minimum steady flight speed in  the landing configuration. In small airplanes, this is the  power-off stall speed at the maximum landing weight in the  landing configuration (gear and flaps down). The lower limit  of the white arc.  V-G diagram.  A chart that relates velocity to load factor. It  is valid only for a specific weight, configuration, and altitude  and shows the maximum amount of positive or negative lift  the airplane is capable of generating at a given speed. Also  shows the safe load factor limits and the load factor that the  aircraft can sustain at various speeds.  Visual approach slope indicator (VASI).  The most  common visual glidepath system in use. The VASI provides  obstruction clearance within 10° of the extended runway  centerline, and to 4 nautical miles (NM) from the runway  threshold.  V$_{S1}$.  Stalling speed or the minimum steady flight speed  obtained in a specified configuration. For most airplanes, this  is the power-off stall speed at the maximum takeoff weight  in the clean configuration (gear up, if retractable, and flaps  up). The lower limit of the green arc.  V$_{SSE}$.  Safe, intentional one-engine inoperative speed. The  minimum speed to intentionally render the critical engine  inoperative.  Visual Flight Rules (VFR).  Code of Federal Regulations  that govern the procedures for conducting flight under visual  conditions.  V-tail.  A design which utilizes two slanted tail surfaces to  perform the same functions as the surfaces of a conventional  elevator and rudder configuration. The fixed surfaces act as  both horizontal and vertical stabilizers.  V$_{LE}$.  Landing gear extended speed. The maximum speed at  which an airplane can be safely flown with the landing gear  extended.  V$_{LOF}$.  Lift-off speed. The speed at which the aircraft departs  the runway during takeoff.  V$_{LO}$.  Landing gear operating speed. The maximum speed for  extending or retracting the landing gear if using an airplane  equipped with retractable landing gear.  V$_{MC}$.  Minimum control airspeed. This is the minimum flight  speed at which a twin-engine airplane can be satisfactorily  controlled when an engine suddenly becomes inoperative  and the remaining engine is at takeoff power.  V$_{MD}$.  Minimum drag speed.  V$_{X}$.  Best angle-of-climb speed. The airspeed at which an  airplane gains the greatest amount of altitude in a given  distance. It is used during a short-field takeoff to clear an  obstacle.  V$_{XSE}$.  Best angle of climb speed with one engine inoperative.  The airspeed at which an airplane gains the greatest amount  of altitude in a given distance in a light, twin-engine airplane  following an engine failure. 