TM 55-1510-222-10 7-1 INTRODUCTION TO PERFORMANCE. The     graphs     and     tables     in     this     Chapter     present performance     information     for     takeoff,     climb,     flight planning  and  landing  at  various  parameters  of  weight, power, altitude, and temperature.  Examples have been presented on performance graphs. 7-2. HOW TO USE GRAPHS. 1. All airspeeds and references to airspeeds in this Chapter are indicated airspeeds unless otherwise noted. 2. A    reference    line    indicates    where    to    begin following  the  guidelines.    Always  project  to  the reference line first, then follow the guidelines to the next item by maintaining the same PROPORTIONAL DISTANCE between the guideline   above   and   the   guideline   below   the projected line.  For instance, if the projected line intersects the reference line in the ratio of 30% down/70%    up    between    the    guidelines,    then maintain this same 30%/70% relationship between  the  guidelines  all  the  way  to  the  next item. 3. The    AIRSPEED    CALIBRATION    -    NORMAL SYSTEM  -  TAKEOFF  GROUND  ROLL  graph was    used    to    obtain    V₁    and    V_R    indicated airspeeds  (IAS).    All  other  indicated  airspeeds were obtained by using the AIRSPEED CALIBRATION - NORMAL SYSTEM graph. 4. The   associated   conditions   define   the   specific conditions  from  which  performance  parameters have  been  determined.    They  are  not  intended to be used as instructions; however, performance values determined from charts can only   be   achieved   if   the   specified   conditions exist. 5. The full amount of usable fuel is available for all approved flight conditions. 6. Notes    have    been    provided    to    approximate performance with the ice vanes extended.  The effect    will    vary,    depending    upon    airspeed, temperature,  and  altitude.    At  lower  altitudes, where  operation  on  the  torque  limit  is  possible, the  effect  of  ice  vane  extension  will  be  less, depending    upon    how    much    power    can    be recovered   without   exceeding   the   N.,   TGT,   or torque limits. 7-3. EXAMPLES. The  following  examples  present  calculations  for  flight time, block speed, and fuel required for a proposed flight from  Billings,  Montana,  to  Casper,  Wyoming,  at  Flight Level  250,  using  the  conditions  listed  below,  except  as noted. a. Conditions.          At     Billings-Logan     International (BIL): Free Air Temperature  ................................ 59°F Field Elevation................................... 3649 feet¹ Altimeter Setting .............................  30.07 in. Hg Wind.................................. 290 DEG at 15 knots Runway 34 Length.............................  5585 feet¹ Gradient ......................................1.9% downhill^{1 1}Source: DOD TERM USLIAPVO1, 12 JAN 89. Route of Trip: BIL - V19 - CPR Route Segment Data: See Table. At Natrona County International (CPR): Free Air Temperature ................................ 68 °F Field Elevation................................... 5348 feet⁴ Altimeter Setting .............................  29.27 in. Hg Wind.................................. 290 DEG at 10 knots Runway 26 Length ............................  8679 feet⁴ Gradient  ............. Not published; zero assumed^{4 4}Source: DOD TERM USLIAPV03, 12 JAN 89. ROUTE SEGMENT DATA² ROUTE AVERAGE MAGNETIC AVERAGE MAGNETIC DISTANCE WIND AT FL 250 FAT AT FL 250 MEA FAT AT MEA ALTIMETER SETTING SEGMENT COURSE VARIATION NM DIR/KNOTS °C FEET °C IN.  HG BIL-SHH 117° 15E 91³ 010°/45 -40 8000 0 29.97 SHH-C_I 139° 14°  E 57 350°/65 -40 9000 -4 29.60 CLI-CPH 161° 13°  E 68³ 310°/50 -30 76000 0 29.48 ²Source:  DOD Low Altitude Enroute Chart L-9, 6 APH 1989. ³lncludes distance between airport and VORTAC, per DOD US IFR SUPPLEMENT, 6 APR 1989 7-3