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There’s a reason why basic airplane attitude instrument flying comes first in any Instrument curriculum – it’s the foundation for everything else you’ll do in IFR flying. If you master airplane attitude instrument flying, then everything else you will do that follows, from departure procedures to instrument approaches, will simply be combining your BAI skills with navigation.
STRAIGHT AND LEVEL
Like your visual flying, most of your instrument time will be spent flying straight and level. As the complete instrument pilot, you should be able to maintain heading, altitude, and airspeed at speeds ranging from cruise to approach. Within the normal speed range of an airplane, there are many combinations of power and pitch which will maintain altitude at different airspeeds. For example, a low power setting and nose high pitch will maintain altitude at low airspeed while a high power setting and low pitch attitude will bring about level flight at high airspeed.
The art of instrument flying involves finesse of the flight controls – fine inputs for precise control. Pitch corrections for level flight should be made using the attitude indicator and limited to half, full, and one and one half bar widths corrections. The pitch corrections to maintain level flight on instruments are smaller than those made using the natural horizon. When the airplane is properly trimmed, the control pressures needed for these small pitch changes are very light. For corrections of more than 100 feet, use a full bar width pitch change initially, changing to a half bar width when the remaining altitude correction is less than 100 feet.
HEADING AND BANK CONTROL
Heading and bank control are virtually the same thing. Heading will stay constant if the wings are kept level in coordinated flight. The wings of the miniature airplane and the horizon bar of the attitude indicator will give you an overall picture of the wing attitude, but small banks are difficult to detect. Small deviations from wings level attitude are more easily detected using the banking scale and center index. Odds are that bank control will require more practice than pitch control. There are several reasons for this. First, the airplane is more stable in pitch than bank and, if you are a typical VFR pilot, you refer to the altimeter more than to the heading indicator.
While the attitude indicator will show if the wings are being kept level, you still need to look at the heading indicator to be sure the heading accurate and that it is kept constant. The attitude and turn indicators provide supporting information regarding bank and everything should agree during straight flight.
The most common error in both pitch and bank control is over controlling. Just as an excessive climb or descent will cause you to overshoot altitude, an excessive rate of turn results in overshooting the target heading.
For heading corrections of five degrees or less, keep the wings level and use rudder pressure to change the heading. Five degrees of heading change doesn’t give you enough time to make a coordinated turn. If heading is off more than five degrees, make a coordinated turn but restrict the banks to half the number of degrees you want to turn but not more than standard rate.
Intentional airspeed changes in level flight are normally accomplished by changing the power. Adjust the power to the setting that you previously determined will produce the desired airspeed. Adjust the pitch attitude to maintain altitude as the airspeed changes. As the airspeed approaches the desired airspeed, the airspeed indicator becomes the primary power instrument and the altimeter is primary for pitch. Fine tune power and pitch as the airplane stabilizes at the new airspeed. And trim to relieve control pressures.
Now let’s take a look at climbs. To enter a constant airspeed climb, raise the nose to bring the miniature airplane the predetermined position above the horizon bar. As the pitch attitude is raised, increase the power to the climb setting and use right rudder to keep the airplane from turning to the left.
Adjustments of the climb attitude will be dictated by the indicated airspeed. If airspeed is too high or low, the pitch attitude must be changed. Don’t chase the airspeed indicator to make the change. Use the attitude indicator to make small changes of one half bar width, wait, and note the effect on the airspeed indicator.
As the desired altitude is approached, the level off must be started at about 10 percent of the rate of climb before reaching the altitude. If the climb is 500 feet per minute, the pitch attitude should be smoothly changed to the level flight attitude 50 feet before reaching the final altitude. Use the attitude indicator to set the level attitude and grade this attitude using the altimeter.
For a constant rate climb, increase the power to the approximate setting required for the desired rate of climb and simultaneously raise the nose to the approximate pitch attitude needed for that climb rate. As the vertical speed indicator stabilizes, it becomes the primary pitch instrument and the airspeed indicator is primary for power. Lead the level off by ten percent of the rate of climb and adjust the pitch and power to the appropriate settings for the desired level airspeed.
Now let’s look at descents. To enter a descent at constant airspeeds up to maximum structural cruise airspeed, simultaneously lower the pitch attitude and reduce power to the predetermined setting. When entering a descent at an airspeed less than cruise, reduce power to the predetermined setting and slow the airplane in level flight. As the airspeed approaches the descent speed, lower the nose to the predetermined attitude.
Make corrections for airspeed by changing pitch attitude and, at the risk of sounding like a broken record, use the attitude indicator to make small pitch changes. To correct a rate of descent at a specific airspeed requires changing both pitch and power. If you start with the predetermined power setting and pitch attitude, any corrections needed will be small.
In order to level off from a descent, you must start your level off before reaching your desired altitude. To do this, lead the level off by about ten percent of the rate of descent. As an example, if you are descending at a rate of 500 feet per minute, lead the level off by about 50 feet. To level off at an airspeed higher than descent speed, lead the level off by 20 to 30 percent of the rate of descent. In the 500 foot per minute example, you would add power and start your level off between 100 and 150 feet before reaching your desired altitude .
BUILD A CHEAT SHEET
It’s good practice to document specific pitch and power settings for various aircraft configurations. You can do this with a flight instructor or safety pilot to determine the most common instrument profiles for your training aircraft. And then when it comes time to execute and fly the specific profiles, it’s only a matter of establishing the predetermined pitch and power to give you the expected performance. Only small adjustments will then be needed for precise control – the art of basic attitude instrument flying.