TM 1-1510-225-10 B-1 APPENDIX B ABBREVIATIONS AND TERMS For   the   purpose   of   this   manual,   the   following abbreviations    and    terms    apply.        See    appropriate technical manuals for additional terms and limits: B-1.  AIRSPEED TERMINOLOGY CAS Calibrated airspeed is indicated airspeed  corrected  for  position  and instrument error. GS Ground  speed  is  the  speed  of  the aircraft relative to the ground IAS Indicated  airspeed  is  the  speed  as shown on the airspeed indicator and assumes no instrument error KTS Knots M Mach   number.      The   ratio   of   true airspeed to the speed of sound. M_mo Maximum  operating  Mach  number. M_mo varies with altitude. TAS True airspeed is calibrated airspeed corrected  for  altitude,  temperature, pressure, and compressibility effects V₁ Takeoff decision speed. The maximum   speed   below   which   the pilot    must    initiate    the    first    action (brake    application)    to    discontinue the  takeoff.    Above  V₁,  the  takeoff must be continued.    V₂ Takeoff    Safety    Speed.        Must    be attained at 35 feet above the runway and  is  the  speed  to  be  maintained during climb to clear an obstacle V_a Maneuvering speed is the maximum speed   at   which   application   of   full available    aerodynamic    control    will not overstress the aircraft. V_enr One     engine     inoperative     enroute climb     speed     with     the     remaining engine at maximum continuous power     setting     for     the     condition, landing gear and flaps retracted. V_f  Design   flap   speed   is   the   highest speed    permissible    at    which    wing flaps may be actuated. V f e Maximum   flap   extended   speed   is the  highest  speed  permissible  with wing  flaps  in  a  prescribed extended position. V_le Maximum    landing    gear    extended speed   is   the   maximum   speed   at which an aircraft can be safely flown with the landing gear extended. V_lo Maximum    landing    gear    operating speed   is   the   maximum   speed   at which the landing gear can be safely extended or retracted. V_mca The  minimum  flight  speed  at  which the aircraft is directionally controllable as determined in accordance    with    Federal    Aviation Regulations.        Aircraft    Certification conditions include one engine becoming  inoperative  and  propeller windmilling;  up  to  a  5 bank toward the  operative  engine;  takeoff  power on   operative   engine;   landing   gear up; flaps up; and most rearward CG. This  speed  has  been  demonstrated to provide satisfactory control above power  off  stall  speed  (which    varied with  weight,  configuration,  and  flight attitude). V_mcg Ground minimum control speed. V mo Maximum     operating     limit     speed. Not   deliberately   exceeded   in   any phase of flight (climb, cruise, descent)  unless  a  higher  speed  is specifically  authorized  for  flight  test or pilot training. V_ne Never exceed speed. V_r Rotation    speed.        The    speed    at which   aircraft   rotation   is   initiated. Varies    with    weight,    altitude,    and temperature. V_ref  The     indicated     airspeed     that     the aircraft  should  be  at  when  50  feet above   the   runway   in   the   landing configuration. V_s Power    off    stalling    speed    or    the minimum     steady     flight     speed     at which the aircraft is controllable.