Instrument flying concept

Instrument flying 

The concept of control and performance attitude instrument flying can be applied. to any aspect of instrument flight. Under this concept, instruments are divided into three broad categories: control, performance and navigation.

1. control instruments: Control instruments indicate attitude of the aircraft and power (thrust/drag) being supplied to the aircraft. These instruments are calibrated to permit adjustments in definite amounts. They include the attitude indicator and engine control instruments (tachometer, manifold pressure, RPM, EPR).

2. performance instruments: Performance instruments indicate the actual performance of the aircraft, which can be determined from

the airspeed/mach, turn-and-bank, vertical speed indicators, altimeters, heading indicator, turn co-ordinator, magnetic compass.

3. navigation instruments: Navigation instruments indicate the position of the aircraft in relation to a particular navigational aid that has been selected. These can include NDB, VOR, ILS, INS, GPS, Loran-C, and OMEGA.

C. Attitude and power control

Proper control of aircraft attitude is the result of knowing when and how much to change attitude, and then smoothly changing it by a definite amount. Aircraft attitude control is accomplished by proper use of the attitude indicator. The attitude indicator provides an immediate, direct and corresponding indication of any change in aircraft pitch and/or bank attitude.

Pitch changes are accomplished by changing the pitch attitude of the reference line by set amounts in relation to the horizon bar. These changes are made in bat widths or degrees, depending upon the type of attitude indicator. On most attitude indicators a bat width represents approximately 2º of pitch change.

Bank changes are accomplished. by changing the bank attitude or bank pointers by set amounts in relation to the bank scale. Normally, the bank scale is graduated by 0º, 10º 20º, 30º, 60º and 90º, and this scale may be located at the top or bottom of the attitude indicator. Generally, an angle of bank that approximates the degrees to be turned is recommended; however, it should not exceed 30º in instrument flight. The TAS and the desired rate of turn are factors to be considered.

Proper power control results from the ability to smoothly establish or maintain desired airspeeds in co-ordination with attitude changes. Power changes are accomplished by throttle adjustment and with reference to the power indicators. Little attention is required to ensure that the power indication remains constant once it is established, because these indications are not affected by such factors as turbulence, improper trim or inadvertent control pressures.