to 1,500 feet in 30 seconds but covers 6,000 feet across the  ground. Note that both ROC and AOC maximum climb  profiles use the aircraft’s maximum throttle setting. Any  differences between max ROC and max AOC lie primarily  in the velocity (airspeed) and AOA combination the aircraft  manual specifies.  [Figure 11-7]  ROC performance depends upon excess power. Since  climbing is work and power is the rate of performing work,  a pilot can increase the climb rate by using any power not  used to maintain level flight. Maximum ROC occurs at an  airspeed and AOA combination that produces the maximum  excess power. Therefore, maximum ROC for a typical jet  airplane occurs at an airspeed greater than L/D$_{MAX}$ and at an  AOA less than L/D$_{MAX}$ AOA. In contrast, maximum ROC for  a typical propeller airplane occurs at an airspeed and AOA  combination closer to L/D$_{MAX}$.  [Figure 11-9]  Since weight, altitude and configuration changes affect  excess thrust and power, they also affect climb performance.  Climb performance is directly dependent upon the ability to  produce either excess thrust or excess power. Earlier in the  book it was shown that an increase in weight, an increase in  altitude, lowering the landing gear, or lowering the flaps all  decrease both excess thrust and excess power for all aircraft.  Therefore, maximum AOC and maximum ROC performance  decreases under any of these conditions.  Weight has a very pronounced effect on aircraft performance.  If weight is added to an aircraft, it must fly at a higher AOA  to maintain a given altitude and speed. This increases the  induced drag of the wings, as well as the parasite drag of the  aircraft. Increased drag means that additional thrust is needed  to overcome it, which in turn means that less reserve thrust is  available for climbing. Aircraft designers go to great lengths  The terms “power loading,” “wing loading,” “blade loading,”  and “disk loading” are commonly used in reference to  performance. Power loading is expressed in pounds per  horsepower and is obtained by dividing the total weight  of the aircraft by the rated horsepower of the engine. It  is a significant factor in an aircraft’s takeoff and climb  capabilities. Wing loading is expressed in pounds per square  foot and is obtained by dividing the total weight of an airplane  in pounds by the wing area (including ailerons) in square feet.  It is the airplane’s wing loading that determines the landing  An increase in altitude also increases the power required  and decreases the power available. Therefore, the climb  performance of an aircraft diminishes with altitude. The  speeds for maximum ROC, maximum AOC, and maximum  and minimum level flight airspeeds vary with altitude. As  altitude is increased, these various speeds finally converge  at the absolute ceiling of the aircraft. At the absolute ceiling,  there is no excess of power and only one speed allows steady,  level flight. Consequently, the absolute ceiling of an aircraft  produces zero ROC. The service ceiling is the altitude at  which the aircraft is unable to climb at a rate greater than 100  feet per minute (fpm). Usually, these specific performance  reference points are provided for the aircraft at a specific  design configuration.  [Figure 11-10]  A change in an aircraft’s weight produces a twofold effect  on climb performance. First, a change in weight changes the  drag and the power required. This alters the reserve power  available, which in turn, affects both the climb angle and  the climb rate. Secondly, an increase in weight reduces the  maximum ROC, but the aircraft must be operated at a higher  climb speed to achieve the smaller peak climb rate.  to minimize the weight, since it has such a marked effect on  the factors pertaining to performance.  Climb Performance Factors  Figure 11-9.  Comparison of maximum ROC between jet and propeller airplanes.  11-8  Power  LEGEND  P$_{E}$ power excess  P$_{A}$ power available  P$_{R}$ power required  ROC  rate of  climb  TAS true airspeed  L/D $_{MAX }$ lift to drag  ratio  maximum  PCL power control lever  Power  (Full PCL) (Full Throttle)  L/D  P$_{E }$ A  R  A  P$_{E }$ P Max ROC (jet)  Max ROC (prop)  P P P R  MAX  L/D $_{MAX }$ Velocity (TAS)  Velocity (TAS) 