Straight and level Flight Straight and level Flight

   Straight and level flight is just what the name implies - flight in which a constant heading and altitude are maintained. It is accomplished by making immediate corrections for deviations in direction and altitude from unintentional slight turns, descents, and climbs.

   The pitch attitude for level flight (constant altitude) is usually obtained by selecting some portion of the airplane's nose as a reference point, and then keeping that point in a fixed position relative to the horizon. That position should be cross checked occasionally against the altimeter to determine whether or not the pitch attitude is correct. If altitude is being gained or lost, the pitch attitude should be readjusted in relation to the horizon and then the altimeter rechecked to determine if altitude is now being maintained. The application of forward or back elevator pressure is used to control this attitude.
The pitch information obtained from the attitude indicator also will show the position of the nose relative to the horizon and will indicate whether elevator pressure is necessary to change the pitch attitude to return to level flight (Fig. 6-2).

   In all normal maneuvers the term "increase the pitch attitude" implies raising the nose in relation to the horizon; the term "decreasing the pitch" means lowering the nose.

   To achieve straight flight (constant heading), the pilot selects two or more outside visual reference points directly ahead of the airplane (such as fields, towns, lakes, or distant clouds, to form points along an imaginary line) and keeps the airplane's nose headed along that line. Roads and section lines on the ground also offer excellent references - straight flight can be maintained by flying parallel or perpendicular to them. While using these references, an occasional check of the heading indicator should be made to determine that the airplane is actually maintaining flight in a constant direction.

   Straight flight (laterally level flight) may also be accomplished by visually checking the relationship of the airplane's wingtips with the horizon. Both wingtips should be equidistant above or below the horizon (depending on whether the airplane is a high wing or low wing type), and any necessary adjustments should be made with the ailerons, noting the relationship of control pressure and the airplane's attitude.
Continually observing the wingtips has advantages other than being a positive check for leveling the wings. It also helps divert the pilot's attention from the airplane's nose, prevents a fixed stare, and automatically expands the radius of visual scanning (Fig. 6-3). In straight and level flight the wingtips can be used for both estimating the airplane's laterally level attitude or bank, and to a lesser degree, its pitch attitude.

   Any time the wings are banked, even though very slightly, the airplane will turn. Thus, close attention should be given to the attitude indicator to detect small indications of bank, and to the heading indicator to note any change of direction.

When the wings are approximately level, straight flight could be maintained by simply exerting the necessary forces on the rudder in the desired direction. However, the practice of using rudder  

alone is not correct and may make precise control of the airplane difficult. Straight and level flight requires almost no application of control pressure if the airplane is properly trimmed and the air is smooth. For that reason, the pilot must not form the habit of constantly moving the controls unnecessarily.

   When practicing this fundamental flight maneuver, the pilot should trim the airplane so it will fly straight and level without assistance. This is called "hands off flight." The trim controls, when correctly used, are aids to smooth and precise flying. Improper trim technique usually results in flying that is physically tiring, particularly in prolonged straight and level flight. By using the trim tabs to relieve all control pressures, the pilot will find that it is much easier to hold a given altitude and heading. The airplane should be trimmed by first applying control pressure to establish the desired attitude, and then adjusting the trim so that the airplane will maintain that attitude without control pressure in "hands off flight."

   For all practical purposes, the airspeed will remain constant in straight and level flight with a constant power setting. Practice of intentional airspeed changes by increasing or decreasing the power, will provide an excellent means of developing proficiency in maintaining straight and level flight at various speeds. Significant changes in airspeed will, of course, require considerable changes in pitch attitude and pitch trim to maintain altitude. Pronounced changes in pitch attitude and trim will also be necessary as the flaps and landing gear are operated.