THE APPROACH AND LANDING

The specific techniques necessary during the phase of approach and landing may vary con­siderably between various types of airplanes and various operations. However, regardless of the airplane type or operation, there are certain fundamental principles which will de­fine the basic techniques of flying during ap­proach and landing. The specific procedures recommended for each airplane type must be followed exactly to insure a consistent, safe landing technique.

THE APPROACH. The approach must be conducted to provide a stabilized, steady flight path to the intended point of touchdown. The approach speed specified for an airplane must provide sufficient margin above the stall speed or minimum control speed to allow satisfactory control and adequate maneuverability. On the other hand, the approach speed must not be greatly in excess of the touchdown speed or a large reduction in speed would be necessary prior to ground contact. Generally, the ap­proach speed will be from 10 to 30 percent above the stall speed depending on the air­plane type and the particular operation.

During the approach, the pilot must attempt to maintain a smooth flight path and prepare for the touchdown. A smooth, steady ap­proach to landing will minimize the transient items of the flight path and provide the pilot better opportunity to perceive and orientate the airplane along the desired flight path. Steep turns must be avoided at the low speeds of the approach because of the increase in drag and stall speed in the turn. Figure 6.4 illus­trates the typical change in thrust required caused by a steep turn. A steep turn may cause the airplane to stall or the large increase in in­duced drag may create an excessive rate of descent. In either case, there may not be suf­ficient altitude to effect recovery. If the air­plane is not properly lined up on the final ap­proach, it is certainly preferable to take a waveoff and go around rather than “press on regardless” and attempt to salvage a decent landing from a poor approach.

The proper coordination of the controls is an absolute necessity during the approach. In this sense, due respect must be given to the primary control of airspeed and rate of descent for the conditions of the steady approach. Thus, the proper angle of attack will produce the desired approach airspeed; too low an angle of attack will incur an excess speed while an excessive angle of attack will produce a deficiency of speed and may cause stall or con­trol problems. Once the proper airspeed and angle of attack are attained the primary control of rate of descent during the steady approach will be the power setting. For example, if it is realized that the airplane is above the de­sired glide path, a more nose-down attitude without a decrease in power setting will result in a gain in airspeed. On the other hand, if it is realized that the airplane is below the desired glide path, a more nose-up attitude without an increase in power setting will simply allow the airplane to fly more slowly and—in the region of reversed command—eventually produce a greater rate of descent. For the conditions of steady flight, angle of attack is the primary control of airspeed and power setting is the primary control of rate of climb and descent. This is especially true during the steady ap­proach to landing. Of course, the ability of the powerplant to produce rapid changes in thrust will affect the specific technique to be used. If the powerplant is not capable of pro­ducing immediate controlled changes in thrust, the operating technique must1 account for this

deficiency. It is most desirable that the power – plant be capable of effecting rapid changes in thrust to allow precise control of the airplane during approach.

The type of approach path is an important factor since it affects the requirement of the flare, the touchdown rate of descent, and—to some extent—the ability to control the point of touchdown. Approach path A of figure 6.4 depicts the steep, low power approach. Such a flight path generally involves a low power setting near idle conditions and a high rate of descent. Precise control of the air­plane is difficult and an excess airspeed usually results from an approach path similar to A. Waveoff may be difficult because of the re­quired engine acceleration and the high rate of descent. In addition, the steep approach path with high rate of descent requires con­siderable flare to reduce the rate of descent at touchdown. This extreme flare requirement will be difficult to execute with consistency and will generally result in great variation in the speed, rate of descent, and point of touchdown.

Approach path C of figure 6.4 typifies the long, shallow approach with too small an inclination of the flight path.- Such a flight path requires a relatively high power setting and a deficiency of airspeed is a usual conse­quence. This extreme of an approach path is not desirable because it is difficult to control the point of touchdown and the low speed may allow the airplane to settle prematurely short of the intended landing touchdown.

Some approach path between the extremes of A and C must be selected, e. g., flight path B. The desirable approach path must not incur excessive speed and rate of descent or require excessive flaring prior to touchdown. Also, some moderate power setting must be required which will allow accurate control of the flight path and provide suitable waveoff characteristics. The approach flight path cannot be too shallow for excessive power setting may be required and it may be difficult to judge and control the point of touchdown. The LSO, mirror landing system, and various approach lighting systems will aid the pilot in achieving the desired approach flight path.