Poper performance requires proper knowledge
A steep approach requires significant drag, which mandates a 40-degree or more maximum flap extension capability--not the maximum of 30 degrees common for many modern airplanes. Airplanes with significant flap-extension capability and high-lift devices are usually classified as a short takeoff and landing (STOL) aircraft.
How do you determine the proper descent angle for your airplane? It's simple. When calm winds exist at your airport, stay at pattern altitude, extend approach (partial) flaps, reduce airspeed, and establish yourself on a longer-than-normal final approach. When it becomes apparent that you are too high to land in that configuration, select idle power, extend full flaps, and descend until it becomes obvious that power is required in order to decrease the descent angle and reach the runway. Add just enough power so that prop is not windmilling--the engine's turning the prop, not the relative wind. Engine power should be no greater than 1,500 rpm or 15 inches of manifold pressure.
After a few attempts, you'll have a perfect idea of your airplane's no-wind descent angle, which would steepen with a headwind or with idle power. The use of idle power, however, is not wise, because you must be able to reduce power during the approach in order to compensate for updrafts.
Folly 2: A short-field approach mandates the approach speed that's published in the pilot's operating handbook. Negative! That speed is valid only if the airplane is at its maximum gross weight for landing and the wind is not gusting--an unlikely situation. Use the speed-adjustment rule-of-thumb: reduce speed 1 percent for every 2 percent below gross weight and increase that speed by 50 percent of the gust factor.
If the airplane's gross weight is 2,400 pounds and actual weight is 2,160 pounds, it is 10 percent below gross weight. If the gross-weight approach speed is 60 knots, reduce it by 5 percent or 3 kt. That will make a difference--it prevents floating. If 10-kt gusts are reported, increase that speed by 5 kt.
I don't know of any true short-field landings sites that report wind, so what do you do in that case? Gusts generate turbulence. Evaluate the turbulence and increase speed using good judgment.
Folly 3: A short-field approach over a 50-foot barrier mandates a steeper descent angle after you clear the barrier. Negative! When obstacles are involved, particularly tree lines or escarpments, do not decrease pitch attitude and reduce power when you clear the obstacle in order to reduce landing distance. Your final approach descent path should be a straight line that just clears the obstacle and extends to the planned touchdown point--go around and make the proper adjustments if you will not land at or within 200 feet beyond that point.
The wind gradient usually changes when you descend below the obstacle, and a pitch and power decrease will generate a high sink rate. This can compromise elevator authority and make it impossible to flare properly for landing, a situation that has caused many short-field landing accidents.
Folly 4: A short-field approach mandates flap retraction and maximum braking immediately after touchdown. Negative! Look at the airplane's performance charts for takeoffs and landings. Landing distance is always shorter than takeoff distance, and with the exception of a forced landing, you most certainly would not land at a site from which you could not depart.
The secret is to fly at the proper speed, maintain your airplane's descent angle, and touch down at the planned point. The airplane will decelerate rapidly, particularly if you maintain a nose-high attitude after landing in order to take advantage of aerodynamic drag. The FAA's practical test standards require maximum braking, so during training and checkrides just announce, "simulating maximum braking." The pilot examiners whom I know consider that to be good judgment.
You'll read or hear about bush pilots who violated the aforementioned procedures, as did I on occasion when flying for the U.S. Army. Please realize that those deviations came from extensive experience, knowledge, and good judgment.
If planning to use true short-field landing sites, you must master basic short-field procedures and practice them until they become habitual. Then and only then are you qualified to determine if a procedural deviation would be prudent.
Ralph Butcher, a retired United Airlines captain, is the chief flight instructor at a California flight school. He has been flying since 1959 and has 25,000 hours in fixed- and rotary-wing aircraft. Visit his Web site.
Related Articles
