text: Maximum endurance in the turbojet air- 
  plane varies with altitude but the variation is 
  due to the changes in ‘fuel flow necessary to 
  provide the thrust required at (I./D),... 
  The 
  low 
  inlet air temperature of the tropopause 
  and the greater engine speed reduce the specific 
  fuel consumption to a minimum. 
  If the single- 
  engine turbojet airplane is at low altitude 
  and must hold or endure for a period of time, 
  a climb should begin to take advantage of the 
  higher specific endurance at higher altitude. 
  The altitude to which to climb will be deter- 
  mined by the quantity of fuel remaining. 
  In 
  the case of the multiengine turbojet at low 
  different procedure 
  altitude, some slightly 
  may be utilized. 
  If all powerplants are oper- 
  ating, it 
  to a higher 
  altitude which is a function of the remaining 
  fuel quantity. An alternative at low altitude 
  
  is desirable to climb 