Understanding the approach angle and aerodynamics will make it easier to fly a controlled smooth approach. Learning to fly an approach is one of the tougher parts of flight training and understanding how plane aerodynamics work.
Angle of Approach Phase of Flight
A discussion of approach angle and aerodynamics refers to the landing phase of flight. The approach angle is the angle you want to fly coming down to the runway for landing. This is the angle between the airplane's flight path and the ground-assuming level ground approaching the runway. The plane's aerodynamics affect the attitude and performance of the aircraft in the approach to landing phase.
To fly a good approach a pilot must control the aircraft speed and angle of approach to reach the landing point in a safe attitude and speed to complete the landing. Flying the approach in visual flight conditions requires a pilot to develop visual references for the correct approach angle when finding how plane aerodynamics work.
Aerodynamics of the Approach
Flying an approach is all about speed and aircraft attitude. The lift generated by an aircraft's wing is a function of the wing's coefficient of lift--CL--and the speed at which the wing is flying. The lift required in the approach is slightly less than the aircraft weight so the aircraft will descend at approximately a 3 degree angle to the landing zone. As an aircraft's speed changes, the angle of the wing in relation to the air flow must change to generate the desired amount of lift. At high speed the wing must be flat into the airflow and as speed slows the angle of the wing towards the airstream will increase to generate the same lift at the slower speed.
The result of this lift vs. speed stuff is that a landing approach should be flown at a constant speed so the aircraft attitude is fixed in relation to the flight path and the pilot has the correct visual references for the approach angle. The old ILS phrase, "on airspeed, on flight path", will make the pilot's visual picture correct for the landing approach.
Flying the Approach Angle
Flying the correct approach angle requires a combination of power and attitude control. Changing power is not to make the plane go slower or faster, it is to move the plane up or down to the correct approach angle. As power is added or retarded the yoke or stick must be pulled or pushed to help with the correction to the desired flight path. As the right approach angle is reached, the reverse power and control movements must be applied to set the planes's path back on the correct approach angle.
Some pilots think of adding power to fly up to the desired flight path and pulling power to descend. Flight attitude is controlled with the flight controls. Depending on the type of plane, thinking this way may make it easier to control the speed and approach angle. With practice , the use of power and controls should become a combined operation to smoothly fly the airplane down the desired approach angle at the correct airspeed.
NASA: Lift Formula
How to Land Airplanes: http://stoenworks.com/Tutorials/How%20to%20land%20airplanes.html
Photo Credit: by Global Jet on Flikr