Last August, I used this page to discuss the point that it often is easier to make good landings with flaps only partially deployed than when they are fully extended. The reason is that using only partial flaps enables a pilot to hold the nose higher during the landing flare and touchdown than when full flaps are used.
Other advantages of approaching and landing with partial flap deployment are:
- improved initial go-around performance;
- reduced susceptibility to wind shear;
- milder inadvertent stalls; and
- better glide performance in case of engine failure.
Furthermore, I indicated that landing with less than full flaps should be done only when runway length is not critical.
A good friend and experienced pilot, however, did not hesitate to tell me that I failed to address the hazards associated with partial-flap landings. As a result, Jack Norris, an FAA inspector and airspace safety coordinator, believes that my views on this subject could do more harm than good.
Norris says that "a considerable number of landing accidents ...occur every month. [More than 2,000 occur in the United States every year.] Many are caused by pilots who either lose directional control or run out of runway." He believes that — for the most part — these "are the result of pilots who fail to adequately control airspeed during the approach. Suggesting the use of partial flaps for landing," Norris adds, "serves only to compound the problem."
As our discussion continued, I had to agree that I had sidestepped two major points. The first involves airspeed control. When the pilot executes an approach with less than full flaps, any power increase or reduction of pitch attitude results in a greater airspeed increase than when flaps are fully deployed. This could be all that is necessary to set up the pilot for an overrun. This is especially significant because an airplane does not decelerate very well during the flare with the flaps only partially extended.
The second major point that Norris made deals with what can happen when a pilot finally notices that he is running out of runway. The safe and obvious thing to do is to execute a go-around and make another, more carefully executed approach. At such a time, however, many pilots fall victim to what psychologists refer to as "landing expectancy." This means that many pilots are "programmed" to land. These pilots will do whatever is necessary to continue the landing, even though common sense dictates otherwise.
Such a pilot typically sees the end of the runway approaching rapidly and senses that he needs to get the airplane on the ground before running out of runway. So instead of biting the bullet and pulling up, he impatiently and erringly pushes forward on the control wheel and forces the aircraft to land nosewheel first or in a three- point attitude. The pilot then exerts additional forward pressure to prevent the airplane from becoming airborne because of its excessive airspeed.
With the nosewheel supporting most of the aircraft weight and the lowered elevator holding the tail high, the main-gear tires barely touch the runway, if at all. At such a time, an airplane begins to behave more like a wheelbarrow than a flying machine. The first indications of this condition are a loss of braking effectiveness and pronounced skipping of the main-gear tires. When these reactions occur, the risk of an overrun can be almost as great as when the airplane is held in the flare to dissipate excess airspeed.
Although wheelbarrowing can lead to an overrun, the greatest potential hazard is the subsequent loss of directional control.
Ever try pushing a wheelbarrow at high speed? Any side force can cause directional instability. An airplane rolling on its nosewheel behaves similarly. A slight crosswind, using nosewheel steering, or just bumping the nosewheel over a clump of dirt on the runway might be all that is necessary to cause the pilot and his passengers to unwittingly shoot off the runway in their airplane like a squeezed watermelon seed or careen out of control in a ground loop. (Yes, airplanes — even large ones — with tricycle landing gear can and do ground loop while wheelbarrowing.)
Airplanes with stabilators are most prone to wheelbarrowing because stabilators typically are more powerful than elevators and more capable of lifting the tail during a ground roll at high speed.
It is surprising that wheelbarrowing is a cause of landing accidents in the first place, considering how easy it is to avoid. If touchdown occurs without an excess of airspeed, in a nose-high attitude, and with the control wheel held well aft of neutral, wheelbarrowing is almost impossible. It occurs most frequently when a pilot bungles the approach by coming in too high or too fast and feels compelled to land despite his poor approach planning.
A pilot usually can recover from wheelbarrowing by simultaneously easing back on the control wheel and temporarily releasing the brakes. This, however, does not ensure against the possibility of a subsequent overrun.
Thanks, Jack, for the reminder that there are two sides to every story.
