Landing procedures

Steps which, when followed, achieve the safe return of an aircraft from the sky to the surface.


Background

A common aviation joke attests that although takeoffs are optional, landings are mandatory. Although landings may seem effortless to nonpilots, landing procedures comprise a large portion of any student pilot’s flight training. As student pilots become more comfortable and proficient at landings, however, they may treat them more lightly. The first aviators, who had no teachers, had to learn how to fly through trial and error. Some early fliers could commit their attention only to getting airborne and allowed landings to take care of themselves, often with tragic consequences. Landing procedures have an obvious purpose: to return the aircraft and its passengers safely to the surface. The first generation of pilots seemed happy to walk away after just about any landing.

Orville and Wilbur Wright equipped their first Flyer with skids instead of wheels, expecting the sands at Kitty Hawk, North Carolina, to intervene and soften the blow of the first landings and the area’s average 16-mile-per-hour winds to allow the Flyer to touch down as slowly as possible. Fortunately, the brothers had gained previous landing experience with gliders designed similarly to their Flyer. However, the powered Flyer differed from the Wrights’ earlier kites and gliders not only in its engine and propellers but also in its substantial pair of skids, which traversed the machine’s length. Later versions of the Flyer repositioned the pilot from a prone to a seated position and strengthened the landing skids and their supports. Wheels remained absent from Wright airplanes until 1910, when the U.S. Army’s purchase demanded specific modifications.

Pilots and designers learned quickly that landing was to be as new a science as was flight itself. At first, there were as many designs and combinations of skids and wheels as there were airplanes. For example, although the Wright brothers did not add wheels to the Flyer design until 1910, in 1909, Louis Blériot used two main wheels on a single axle under the engine and equipped his airplane with a non-steerable tailwheel. In the same year, the Antoinette airplane was built, with two main wheels behind the engine, a spoon-shaped skid poking ahead of the main wheels, and another skid beneath the tail. These skids absorbed the shock of landings performed by inexperienced pilots.



Landing Fields

Early aviators used landing fields that were, as their name implies, open fields, in which pilots could point their airplanes directly into the prevailing winds. This orientation ensured that each landing could be made directly into the wind, for early airplanes’ controls were usually too weak or unbalanced to permit reliable crosswind landings. Crosswind landing capabilities are essential in modern airplanes, because runways long ago replaced landing fields. Whenever winds blow cleanly down the runway’s length, crosswinds pose no challenge. The greater the wind’s angle to a runway’s centerline, the more skill a pilot must demonstrate to make a safe landing. Much of the reason for this difficulty is because airplanes in flight move about the concentration of mass that pilots call the center of gravity. If an airplane could be held off the ground by a cable attached at its center of gravity, it would remain balanced, with both wings and nose level. As runways became more prevalent after the 1930’s, pilots had to develop techniques to prevent any crosswinds from pushing on their airplanes’ vertical stabilizers. As an airplane slows after landing, side winds hit the vertical stabilizer, much as they fill the sail of a boat. More force concentrates on the tail, as the wind pushes against the entire airplane, and the tail moves downwind, as the nose swings in the opposite direction. As the airplane slows, the crosswind’s force can become great enough that the rudder can no longer overcome it, causing the pilot to lose control and forcing the airplane off the runway. Crosswind landing techniques emerged to counter this threat.



Landing Techniques

The earliest and most basic landing technique involves the pilot crabbing the airplane into the wind until just a moment before touchdown. At the split second before the tires contact the runway, the pilot straightens the nose relative to the runway using the rudder. This technique causes the airplane’s wheels to touch the surface with little sideload but requires that the airplane be stopped quickly. Because so many early airplanes were tailwheel types, quick stops were not always possible. Many airplanes ran off the runway, or ground-looped. However, the technique found wide acceptance on broad grass runways. From the 1950’s on, more costly, and, therefore, more narrow, paved runways became the norm. Landing accidents increased, not because pavement was a more difficult landing medium to master, but because crosswind techniques on pavement required a crisper, more certain control technique.

In the days before airplanes had landing flaps, pilots could lose altitude quickly and safely by slipping, a technique wherein the pilot lowers one wing and keeps the airplane from turning by using the opposite rudder. The same technique, refined by a pilot’s delicate touch, worked well to land an airplane in a strong crosswind. By lowering the wing into the wind, a pilot could use the airplane’s lift to maintain position on a runway’s centerline. Touching down on the upwind wheel allowed pilots to maintain directional control by using the rudder. An airplane’s fuselage, no longer streamlined into the wind, provided welcome aerodynamic drag to slow the airplane quickly, so the moment between the flight controls losing effectiveness and the airplane slowing to the point that most crosswinds would not push the tail became minimum.

The point at which a wind becomes too strong to allow a proficient pilot to land safely is called the maximum crosswind component of the airplane’s performance envelope. At end of the twentieth century, the U.S. Federal Aviation Administration (FAA) recognized only the slip-to-landing crosswind technique. Straightening the nose at the last moment required too unreliable a sense of timing and was simply less safe than the slip-to-landing technique.

The particular technique that a pilot uses to land an aircraft depends on several things, including the airplane’s landing gear, the length of the runway, and the runway’s surface. The three basic landing techniques are the normal landing, the soft-field landing, and the short-field landing.



Normal Landings

Pilots elect to make normal landings when the available runway length allows plenty of room, there are no obstructions to approach, and the runway surface is smooth, hard, and dry. Practiced normal landings appear effortless to observers but require much skill and judgment on the part of the pilot. Student pilots normally begin their flight training with normal landings, the simplest of landing techniques.

In normal landings, pilots must align their airplanes with the runway centerline and, maintaining an appropriate airspeed, plan a stable approach path to the runway. Airspeed control is critical during all types of landings, because the goal is always to touch down with as little downward motion as possible in order to prevent damage to the landing gear. The second critical part of landing is airspeed control. If the airspeed is too slow on approach, the pilot may lose control of the airplane. If the airspeed is too fast, the pilot may not be able to touch down at the appropriate point, using up too much runway and damaging the airplanes at the end of the runway.



Soft-Field Landings

Soft-field landings require a high degree of pilot awareness, because the pilot essentially handles the controls as if to keep the airplane flying until the wings simply stop producing enough lift for flight. This procedure must be timed so that all of the aircraft’s wheels touch the runway surface at the same moment. After the wheels touch, the pilot must apply just enough power to reduce the nosewheel’s pressure on the runway by applying back pressure on the stick, or yoke, by pulling the stick forward with very light hand pressure. The pilot continues to apply back pressure until the airplane slows so much that the weight of the nose finally rests fully on the rolling nosewheel.

Because there are so many types of runway surfaces, pilots must use extreme care and near-faultless judgment to analyze and properly land on a soft field. Pilots must avoid portions of the runway that might damage their airplanes. Obstacles such as broken concrete, badly eroded asphalt, snow packed to iceberg hardness, or windborne debris can contaminate a landing field. Special caution is also essential on grass or dirt runways after a rain. Muddy surfaces can stop an airplane so suddenly as to flip the airplane over.



Short-Field Landings

Pilots use the short-field landing technique when a runway is shorter than normal. Short-field landings demand skill and practice, because they require pilots to touch down on or near a specific point at the lowest safe airspeed. After all wheels have made contact with the surface, pilots must apply heavy braking to stop the airplane in the shortest distance. Successful short-field landings require a pilot’s heavy reliance on the pilot’s skill and judgment. Student pilots practice short-field landings throughout most of their training, and their flight instructors emphasize them with increasing frequency as students approach their practical test. Airspeed control, pitch attitude control, and power control blend together through the pilot’s hand in a ballet of momentum management that ends in a thrilling dissipation of energy.

U.S. Navy pilots are, in effect, making short-field landings when they land on aircraft carriers. They rely on shipboard signal officers, who manually signal essential corrections, as they concentrate on lighted approach-slope aids. A properly flown approach to the short field of an aircraft carrier results in the airplane’s tailhook grabbing a landing cable, which slows the airplane violently but certainly on a pitching, rolling runway. A civilian pilot has only the airplane’s brakes and flap retraction to stop the airplane on the runway after the pilot’s visual judgment places the airplane on its touchdown point.

Regardless of the type of landing a pilot selects, consistency is the key to success. Pilots attain and maintain consistency by keeping in practice. U.S. regulations have long required pilots to have landed at least three times within the ninety days preceding a flight carrying passengers.

Landings have fulfilled aviators, met schedules, thrilled passengers, and even saddened those experiencing flight’s end. Aviation has inspired poets in most of its aspects, but landings have received rare poetic treatment. In 1956, F. Pratt Green recounted his emotion at the moment of landing, and of exiting the airplane to meet loved ones at the fence in his five-part poem “Return to Earth.

Odd, then, that to alight on a runway

was to die another death. Required

to declare our love, we found nothing

to say to those who at barriers waited

to embrace us. Our return to earth,

we felt, was to be mourned, not fêted.



Bibliography

  • Roberts, Joseph, and Paul Briand, eds. The Sound of Wings: Readings for the Air Age. New York: Henry Holt, 1957. A collection of prose and poetry covering the history of aviation from its inception to the rocket age.
  • Taylor, John, ed. The Lore of Flight. New York: Mallard Press, 1990. A thorough and informative historical overview of most aspects of aviation, including landing-gear design development. Profusely illustrated with line and color drawings and photographs.
  • Wright, Orville. How We Invented the Airplane. Reprint. New York: Dover, 1988. An unabridged republication of the 1953 work edited by Fred C. Kelly and written in 1920 by Orville Wright. Illustrated with photos discovered up to 1988.


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