TM 1-1510-218-10 5-13 b.  Operations   Over   12,500   Pounds   Gross Takeoff Weight C  D1  . (1)  Requirements. Artificial  stall  warning  systems  may  only provide a 1 to 5 knot stall warning. CAUTION Maximum   Gross   Takeoff   Weight   charts must be strictly followed during performance    planning    to    ensure    climb capability in the event of an engine failure during takeoff. (a)  Takeoffs.      Takeoffs   shall   only   be performed on a smooth paved runway.  Takeoffs shall not be performed with a tailwind. (b)  Landing.  Maximum landing weight is 12,500  pounds.    Landings  shall  only  be  made  on  a smooth   paved   runway   and   the   sink   rate   shall   not exceed 500 feet per minute. (c)   Flight   Altitude   and   Duration.      All missions  with  over  12,500  pounds  GTOW  shall  be planned  and  flown  at  or  above  10,000  feet  above ground  level   and   be   a  minimum  of  60  minutes  in duration    unless   restricted    by    Air   Traffic    Control, turbulence, other weather conditions, or emergencies. (d)  Center  of  Gravity  (CG)  Limits.    The CG limits shall be IAW with Figure 6-8. 1  The   aft   CG   limit   above   12,500 pounds is 196.4 ARM inches. 2  The   forward   CG   limit   at   13,500 pounds is 188.3 ARM inches.  Intermediate values to 12,500 vary linearly to 185.0 ARM inches. (e)  Limited Applicability to Certain Aircraft.    The  following  aircraft  are  authorized  to  be operated at weights greater than 12,500 pounds only if the wing spars have been replaced after 10,000 hours of service. C–12C 73–22250 73–22252 through 73–22264 73–22267 through 73–22269 c.  Operations   Over   12,500   Pounds   Gross Takeoff Weight D2 T . (1)  Requirements. Artificial  stall  warning  systems  may  only provide a 1 to 5 knot stall warning. CAUTION Maximum   Gross   Takeoff   Weight   charts must be strictly followed during performance    planning    to    ensure    climb capability in the event of an engine failure during takeoff. (a)  Aircraft     shall     be     equipped     with Raisbeck   Engineering   dual   aft   body   strakes   and engine    ram    air    recovery    system    with    PT6A–42 engines. (b)  Landing.  Maximum landing weight is 12,500 pounds, unless required by an emergency.  If it is necessary to land with a weight over 12,500 pounds, the landing shall be made on a smooth, paved runway at a sink rate of 500 feet per minute or less, if possible. (c)   Flight   Altitude   and   Duration.      All missions  with  over  12,500  pounds  GTOW  shall  be planned  and  flown  at  or  above  10,000  feet  above ground  level   and   be   a  minimum  of  60  minutes  in duration    unless   restricted    by    Air   Traffic    Control, turbulence, other weather conditions, or emergencies. (d)  Takeoff.        All    missions    with    over 12,500  pounds  GTOW  shall  be  flown  on  a  smooth, paved runway.  Takeoffs shall not be performed with a tailwind. Section V.  AIRSPEED LIMITS, MAXIMUM AND MINIMUM 5-21.  AIRSPEED LIMITATIONS. Airspeed indicator readings contained in procedures,   text,   and   illustrations   throughout   this Operator’s  Manual  are  given  as  indicated  airspeed (IAS).    Airspeed  indicator  markings  Figure  5-1  and placarded airspeeds, located on the cockpit overhead control  panel,  Figure  2-15,  are  Calibrated  Airspeeds (CAS)   C      D   and   Indicated   Airspeeds   (IAS)   T   . Airspeed Calibration Charts are in Chapter 7. WARNING WARNING