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With experience and practice, altitudes up to approximately 1,000 feet can be estimated with fair accuracy, while above this level the accuracy in judgment of height above the ground decreases since features tend to merge. The best aid in perfecting the ability to judge height above this altitude is altimeter indications and associating them with the general appearance of the Earth. 

The judgment of altitude in feet, hundreds of feet, or thousands of feet is not as important as the ability to estimate gliding angle and its resultant distance. The pilot who knows the normal glide angle of the aircraft can estimate with reasonable accuracy the approximate spot along a given ground path at which the aircraft lands, regardless of altitude. The pilot who also has the ability to estimate altitude accurately can judge how much maneuvering is possible during the glide, which is important to the choice of landing areas in an actual emergency. 

Unlike a normal approach in which power is available when needed, for a power-off approach the power is fixed at the idle setting. Pitch attitude is adjusted to control the airspeed, which also changes the glide or descent angle. As discussed in the basic flight maneuvers descents and the steep approach maneuver, lowering the nose to a speed above the best glide angle causes the descent angle to steepen. If the airspeed is too high, raise the nose, and when the airspeed is too low, lower the nose. If the pitch attitude is raised too high, the aircraft settles rapidly due to low airspeed and insuffi cient lift. For this reason, never try to stretch a glide to reach the desired landing spot. 

Uniform approach patterns such as the 90°, 180°, or 360° power-off approaches are described further in this chapter. Practice in these approaches provides the pilot with a basis on which to develop judgment in gliding distance and in 

planning an approach. The 180° power-off approach from pattern altitude should be the normal landing procedure in calm winds. This should become routine and develop the ability to accurately judge the landing for an engine-out situation. Remember, the steep approach technique can always be used if the aircraft is a little high, but do not stretch a glide by lowering the speed if too low. 

The basic procedure in these approaches involves closing the throttle at a given altitude and gliding to a key position. This position, like the pattern itself, must not be allowed to become the primary objective; it is merely a convenient point in the air from which the pilot can judge whether the glide safely terminates at the desired spot. The selected key position should be one that is appropriate for the available altitude and the wind condition. From the key position, the pilot must constantly evaluate the situation. It must be emphasized that, although accurate spot touchdowns are important, safe and properly executed approaches and landings are vital. The pilot must never sacrifice a good approach or landing just to land on the desired spot. 

All power-off approaches must be practiced to avoid interfering with normal traffi c flow at busy airports, so the place and timing must be evaluated by the instructor to prevent airport traffi c conflicts. This is especially important for the 360° power-off approach. 

##  90° Power-Off Approach 

The 90° power-off approach is made from a base leg and requires only a 90° turn onto the final approach. The approach path may be varied by positioning the base leg closer to or farther away from the approach end of the runway according to wind conditions. [Figure 11-31]  The glide from the key 

