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| CHAPTER 11. Approaches and Landings
Ballooning During Roundout If the pilot misjudges the rate of sink during a landing and thinks the aircraft is descending faster than it should, there is a tendency to increase the pitch attitude and AOA too rapidly. This not only stops the descent, but actually starts the aircraft climbing. This climbing during the roundout is known as ballooning. Ballooning can be dangerous because the height above the ground is increasing and the aircraft may be rapidly approaching a stall. The altitude gained in each instance depends on the airspeed or the speed with which the pitch attitude is increased. When ballooning is slight, the nose should be lowered to increase speed and return to a gradual descent. Recovery procedures are similar to those for rounding out too high: lowering the nose slightly and increasing the throttle to remain level. Then, the pilot gradually reduces throttle and speed for a controlled descent rate with the throttle at idle during touchdown. When ballooning is excessive, it is best to execute a goaround immediately; do not attempt to salvage the landing. Full power must be applied and the nose lowered before the aircraft enters a stalled condition. The pilot must be extremely cautious of ballooning when there is a crosswind present because the crosswind correction may be inadvertently released or it may become inadequate. Because of the lower airspeed after ballooning, the crosswind affects the aircraft more. Consequently, crabbing has to be increased to compensate for the increased drift. It is imperative that the pilot makes certain that directional control is maintained. If there is any doubt, or the aircraft starts to drift, execute a go-around. Bouncing During Touchdown When the aircraft contacts the ground with a sharp impact as the result of an improper attitude or an excessive rate of sink, it can bounce back into the air. The severity of the bounce depends on the airspeed at the moment of contact and the rebound attitude the WSC aircraft. It can increase the AOA and, in addition to bouncing, be lifted. It can rebound in a yawed condition and/or nose up or down. Design and situational factors create their own unique scenarios. The corrective action for a bounce is the same as for ballooning and similarly depends on its severity. When the bounce is very slight and there is not an extreme change in the aircraft’s pitch attitude, a follow-up landing may be executed by applying suffi cient power to cushion the subsequent touchdown and smoothly adjusting the pitch to the proper touchdown attitude. Extreme caution and attention must be exercised any time a bounce occurs, but particularly when there is a crosswind. During the bounce, the wind causes the aircraft to roll with the wind, thus exposing even more surface to the crosswind and drifting the aircraft more rapidly. When a bounce is severe, the safest procedure is to execute a go-around immediately. No attempt to salvage the landing should be made. Full power should be applied while simultaneously maintaining directional control and lowering the nose to a safe climb attitude. The go-around procedure should be continued even though the aircraft may descend and another bounce may be encountered. It would be extremely foolish to attempt a landing from a bad bounce since airspeed diminishes very rapidly in the nose-high attitude, and a stall may occur before a subsequent touchdown could be made. Porpoising In a bounced landing that is improperly recovered, the aircraft comes in nose fi rst, setting off a series of motions that imitate the jumps and dives of a porpoise—hence the name. The problem is improper aircraft attitude at touchdown, sometimes caused by inattention, not knowing where the ground is, or forcing the aircraft onto the runway at an exceedingly high descent rate. Porpoising can also be caused by improper airspeed control. Usually, if an approach is too fast, the aircraft fl oats and the pilot tries to force it on the runway when the aircraft still tends to fl y. A gust of wind, a bump in the runway, or even a slight push on the control bar sends the aircraft aloft again. The corrective action for a porpoise is the same as for a bounce, and similarly depends on its severity. When it is very slight with no extreme change in the aircraft’s pitch attitude, a follow-up landing may be executed by applying suffi cient power to cushion the subsequent touchdown, and smoothly adjusting the pitch to the proper touchdown attitude. When a porpoise is severe, the safest procedure is to execute an immediate go-around. In a severe porpoise, the aircraft’s pitch oscillations can become progressively worse until the aircraft strikes the runway nose fi rst with suffi cient force to collapse the nose gear. Pilot attempts to correct a severe porpoise with fl ight control and power inputs will most likely be untimely and out of sequence with the oscillations, only making the situation worse. No attempt to salvage the landing should be made. Full power should be applied while simultaneously maintaining directional control and lowering the nose to a safe climb attitude. |
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