airspeed results in a proportional change in the distance flown.  [Figure 3-24]  As the glide airspeed is increased or decreased  from the best glide airspeed, the glide ratio is lessened.  obstacles during a landing approach to a short runway. The  airspeed used for this descent condition is recommended by  the AFM/POH and is normally no greater than 1.3 V$_{SO}$. Some  characteristics of the minimum safe airspeed descent are a  steeper-than-normal descent angle, and the excessive power  that may be required to produce acceleration at low airspeed  should “mushing” and/or an excessive rate of descent be  allowed to develop. Variations in weight do not affect the glide angle provided  the pilot uses the proper airspeed. Since it is the L/D ratio that  determines the distance the airplane can glide, weight does  not affect the distance flown; however, a heavier airplane  must fly at a higher airspeed to obtain the same glide ratio.  For example, if two airplanes having the same L/D ratio but  different weights start a glide from the same altitude, the  heavier airplane gliding at a higher airspeed arrives at the  same touchdown point in a shorter time. Both airplanes cover  the same distance, only the lighter airplane takes a longer time. Emergency descent—some airplanes have a specific  procedure for rapidly losing altitude. The AFM/POH specifies  the procedure. In general, emergency descent procedures are  high drag, high airspeed procedures requiring a specific  airplane configuration (such as power to idle, propellers  forward, landing gear extended, and flaps retracted) and a  specific emergency descent airspeed. Emergency descent  maneuvers often include turns. Since the highest glide ratio occurs at maximum L/D, certain  considerations must be given for drag producing components  of the airplane, such as flaps, landing gear, and cowl flaps.  When drag increases, a corresponding decrease in pitch  attitude is required to maintain airspeed. As the pitch is  lowered, the glide path steepens and reduces the distance  traveled. To maximize the distance traveled during a glide,  all drag producing components must be eliminated if possible.  A glide is a basic maneuver in which the airplane loses  altitude in a controlled descent with little or no engine power;  forward motion is maintained by gravity pulling the airplane  along an inclined path and the descent rate is controlled by  the pilot balancing the forces of gravity and lift. To level off  from a partial power descent using a 1,000 feet per minute  descent rate, use 10 percent (100 feet) as the lead point to  begin raising the nose to stop descent and increasing power  to maintain airspeed. Wind affects the gliding distance. With a tailwind, the  airplane glides farther because of the higher groundspeed.  Conversely, with a headwind, the airplane does not glide as  far because of the slower groundspeed. This is important for  a pilot to understand and manage when dealing with engine- related emergencies and any subsequent forced landing. Certain considerations must be given to gliding flight. These  considerations are caused by the absence of the propeller  slipstream, compensation for p-factor in the airplane’s  design, and the effectiveness of airplane control surfaces  Although glides are directly related to the practice of power- off accuracy landings, they have a specific operational purpose  in normal landing approaches, and forced landings after engine  failure. Therefore, it is necessary that they be performed  more subconsciously than other maneuvers because most of  the time during their execution, the pilot will be giving full  attention to details other than the mechanics of performing the  maneuver. Since glides are usually performed relatively close  to the ground, accuracy of their execution and the formation  of proper technique and habits are of special importance.  The glide ratio of an airplane is the distance the airplane  travels in relation to the altitude it loses. For example, if an  airplane travels 10,000 feet forward while descending 1,000  feet, its glide ratio is 10 to 1.  The best glide airspeed is used to maximize the distance  flown. This airspeed is important when a pilot is attempting  to fly during an engine failure. The best airspeed for gliding  is one at which the airplane travels the greatest forward  distance for a given loss of altitude in still air. This best  glide airspeed occurs at the highest lift-to-drag ratio (L/D).  [Figure 3-23]  When gliding at airspeed above or below the  best glide airspeed, drag increases. Any change in the gliding  3-20 Figure 3-23.  L/D$_{MAX}$. Glides Increasing Lift-to-drag ratio Increasing angle of attack L/D$_{MAX}$