reverse thrust increases with speed; and the power produced  is higher at higher speeds because of the increased rate of  doing work. In other words, the kinetic energy of the airplane  is being destroyed at a higher rate at the higher speeds. To get  maximum efficiency from reverse thrust, therefore, it should  be used as soon as is prudent after touchdown. When considering the proper time to apply reverse thrust  after touchdown, the pilot should remember that some  airplanes tend to pitch nose up when reverse is selected on  landing and this effect, particularly when combined with the  nose-up pitch effect from the spoilers, can cause the airplane  to leave the ground again momentarily. On these types, the  airplane must be firmly on the ground with the nose wheel  down before reverse is selected. Other types of airplanes  have no change in pitch, and reverse idle may be selected  after the main gear is down and before the nose wheel is  down. Specific procedures for reverse thrust operation for a  particular airplane/engine combination are contained in the  FAA-approved AFM for that airplane. There is a significant difference between reverse pitch on  a propeller and reverse thrust on a jet. Idle reverse on a  propeller produces about 60 percent of the reverse thrust  available at full power reverse and is therefore very effective  at this setting when full reverse is not needed. On a jet engine,  however, selecting idle reverse produces very little actual  reverse thrust. In a jet airplane, the pilot must not only select  reverse as soon as reasonable, but then must open up to full  power reverse as soon as possible. Within AFM limitations,  full power reverse should be held until the pilot is certain  the landing roll is contained within the distance available. There are usually three general sensations that the pilot  transitioning into jets will immediately become aware of.  These are: response differences, increased control sensitivity,  and a much increased tempo of flight. Inadvertent deployment of thrust reversers while airborne is  a very serious emergency situation. Therefore, thrust reverser  systems are designed with this prospect in mind. The systems  normally contain several lock systems: one to keep reversers  from operating in the air, another to prevent operation with  the thrust levers out of the idle detent, and/or an “auto-stow”  circuit to command reverser stowage any time thrust reverser  deployment would be inappropriate, such as during takeoff and  while airborne. It is essential that pilots understand not only  the normal procedures and limitations of thrust reverser use,  but also the procedures for coping with uncommanded reverse.  Those emergencies demand immediate and accurate response. In many flight conditions, airspeed changes can occur more  slowly than in a propeller airplane. This arises from different  effects. At high altitudes, the ability to accelerate lessens due  to the reduction in available thrust. Another effect is the long  spool-up time required from low throttle settings. Some  aircraft can take on the order of 8–10 seconds to develop  full thrust when starting from an idle condition. Finally, the  clean aerodynamic design of a jet can result in smaller than  expected decelerations when thrust is reduced to idle. The lack of propeller effect is also responsible for the lower  drag increment at the reduced power settings and results in  other changes that the pilot will have to become accustomed  to. These include the lack of effective slipstream over the  lifting surfaces and control surfaces, and lack of propeller  torque effect. The aft mounted engines will cause a different reaction to  power application and may result in a slightly nosedown  pitching tendency with the application of power. On the  other hand, power reduction will not cause pitch changes to  the same extent the pilot is used to in a propeller airplane.  Although neither of these characteristics are radical enough  to cause transitioning pilots much of a problem, they must  be compensated for. Power settings required to attain a given performance are  almost impossible to memorize in the jets, and the pilot who  feels the necessity for having an array of power settings for  all occasions will initially feel at a loss. The only way to  answer the question of “how much power is needed?” is  by saying, “whatever is required to get the job done.” The  primary reason that power settings vary so much is because  of the great changes in weight as fuel is consumed during the  flight. Therefore, the pilot will have to learn to use power as  needed to achieve the desired performance. In time, the pilot will find that the only reference to power  instruments will be that required to keep from exceeding  limits of maximum power settings or to synchronize rpm. Proper power management is one of the initial problem areas  encountered by the pilot transitioning into jet airplanes.  Although smooth power applications are still the rule, the  pilot will be aware that a greater physical movement of the  power levers is required as compared to throttle movement  in the piston engines. The pilot will also have to learn to  anticipate and lead the power changes more than in the past  and must keep in mind that the last 30 percent of engine rpm  represents the majority of the engine thrust, and below that  the application of power has very little effect. In slowing the  Pilot Sensations in Jet Flying 15-17