Historically, more incidents and accidents occur during the landing phase of flight than any other time. A look at the numbers shows pilots do a notoriously lousy job of ending their flights.
Overruns, landing short, loss of control on the runway, bounces that collapse landing gear, porpoises that bend firewalls, the list of woes goes on and on. This record points to the importance of increasing landing skills and building your pride in being a proficient pilot.
Although the concept of a stabilized landing approach has been around for 10 or 12 years, how many pilots actually use one? Seldom do I see anyone on a flight review, or checkout who uses the method.
Its often said that a good landing starts with a good approach. That may or may not be a worthwhile generalization, but its undisputable that the traffic pattern and landing approach are common places where the conditions for a poor landing start to build up.
A stabilized approach means that your aircraft is on the glide path at a correct descent angle and rate, and on the airspeed that is best suited to your pattern position, airplane configuration and weight.
The concept was originally presented at the EAA Convention at Oshkosh in 1989 by Jeffrey A. Roy, Aviation Safety Program Manager for the FAAs New England Region.
The target airspeed for 50 feet above the runway on short final is the reference speed, Vref, which is based on the airplanes stall speed and landing weight and is the commonly referred to 1.3 times Vso. The manufacturers for light airplanes dont provide a Vref in the operating handbook, but they usually do publish a final approach speed, which is essentially the same thing.
The speeds are given for the maximum landing weight, and remember that stall speeds typically decrease as weight decreases, so a lightly loaded airplane coming in at Vref may actually be coming in hot.
To make a stabilized approach work the best, you must have a specific target speed for each segment of the approach. Few manufacturers provide these figures specifically, but they are easily determined from the aircrafts landing distance tables or Vref.
An easy way to approximate the technique, and what I teach, is to add five knots to Vref for final approach, another five for the base leg, another five for downwind and finally, another five for pattern entry speed. Of course you can convert to miles per hour, if you have those dials.
Lets assume we have a Piper PA-28-161 Warrior. The approach speed published in the landing distance table is 65 knots, so use 65 knots for Vref. Add five knots to get 70 knots for final, then five more for base leg (75 knots), another five knots for downwind (80 knots) and five knots more for pattern entry speed (85 knots).
Of course a stabilized approach requires using the proper relationship of pitch and power. Pitch and power must be adjusted together to guarantee proper airspeed and glide path. The RPM, manifold pressure or torque setting it takes to maintain straight and level flight at Vref+40 is the reference power setting for a stabilized approach.
Lets say 2300 rpm provides Vref+40 in the Warrior. As you turn on the entry leg, slow to 85 knots by reducing power to 2100 rpm. Downwind, with 20 degrees of flaps, 1900 rpm will get 80 knots. The base leg will take 1800 rpm to maintain 75 knots. Final approach, with full flaps and a 500 fpm descent at 65 knots will take 1650 rpm.
For a complex airplane, reducing one inch of manifold pressure at each step may produce the same result. The specific numbers depend on the specific model of airplane, but these numbers will get you started in working out the proper power settings in your airplane.
Keeping the power changes small on final will get the desired end result – a stabilized approach and landing. If there is a crosswind, that same magical 50 feet above the runway is the place to begin your forward slip.
If you havent tried this type of approach, give it a shot. Youll surprise your CFI on your next flight review. But more important, youll find your landings will probably improve dramatically, crosswind or not. It gives you a set of benchmarks you can rely on rather than flying using the that looks about right method.
-by Raymond Leis
Raymond Leis is a CFII and ATP with more than 23,000 hours.
