However remote you may consider the chance of your making an IFR departure under completely "blind" weather conditions, your competency in instrument takeoff will provide the proficiency and confidence necessary for use of flight instruments during departures under conditions of low visibility, rain, low ceilings, or disorientation at night. A sudden rapid transition from "visual" to "instrument" flight can result in serious disorientation and control problems.
Instrument takeoff techniques vary with different types of airplanes, but the method described below is applicable whether the airplane is single or twin-engine; tricycle-gear or conventional-gear.
Align the airplane with the centerline of the runway with the nosewheel or tailwheel straight. (Your instructor may align the airplane if he has been taxiing while you perform the instrument check under a hood or visor.) Lock the tailwheel, if so equipped, and hold the brakes firmly to avoid creeping while you prepare for takeoff. Set the heading indicator with the nose index on the 5° mark nearest the published runway heading, so that you can instantly detect slight changes in heading during the takeoff. Make certain that the instrument is uncaged (if it has a caging feature) by rotating the knob after uncaging and checking for constant heading indication. If you use an electric heading indicator with a rotatable needle, rotate the needle so that it points to the nose position, under the top index. Advance the throttle to an RPM that will provide partial rudder control. Release the brakes, advancing the power smoothly to takeoff setting. During the takeoff roll, hold the heading constant on the heading indicator by the use of rudder. In multiengine, propeller-driven airplanes, also use differential throttle to maintain direction. The use of brakes should be avoided, except as a last resort, as it usually results in overcontrolling and extending the take-off roll. Once you release the brakes, any deviation in heading must be corrected instantly.
As the airplane accelerates, cross-check both heading indicator and airspeed indicator rapidly. As flying speed is approached (approximately 15-25 knots below takeoff speed), apply elevator control smoothly for the desired takeoff attitude on the attitude indicator. This is approximately a 2-bar-width climb indication for most light airplanes.
Continue with a rapid cross-check of heading indicator and attitude
indicator as the airplane leaves the ground. Do not pull it off; let it
fly off while you hold the selected attitude constant. Maintain pitch and
bank control by reference to the attitude indicator, and make coordinated
corrections in heading when so indicated on the heading indicator. Cross-check
the altimeter and vertical-speed indicator for a positive rate of climb
(steady clockwise rotation of the altimeter needle at a rate that you can
interpret with experience, and a stable rate of climb appropriate to the
airplane shown on the vertical-speed indicator).
When the altimeter shows a safe altitude (approximately 100 feet), raise the landing gear and flaps, maintaining attitude by reference to the attitude indicator. Because of control pressure changes during gear and flap operation, overcontrolling is likely unless you note pitch indications accurately and quickly. Trim off control pressures necessary to hold the stable climb attitude. Check the altimeter, vertical-speed indicator, and airspeed for a smooth acceleration to predetermined climb speed (altimeter and airspeed increasing, vertical speed stable). At climb speed, reduce power to climb setting (unless full power is recommended for climb by your airplane flight handbook) and trim.
Throughout the instrument takeoff, cross-check and interpretation must be rapid, and control positive and smooth. During liftoff, gear and flap retraction, and power reduction, the changing control reactions demand rapid scanning, adjustment of control pressures, and accurate trim changes.
Common errors during the instrument takeoff include the following,
1. Failure to perform an adequate cockpit check before the takeoff.
Ridiculous as it seems, students have attempted instrument takeoffs with
inoperative airspeed indicators (pitot tube obstructed), gyros caged, controls
locked, and numerous other oversights due to haste or carelessness.
2. Improper alignment on the runway. This may result from improper brake application, allowing the airplane to creep after alignment, or from alignment with nosewheel or tailwheel cocked. In any case, the result is a built-in directional control problem as the takeoff starts.
3. Improper application of power. Abrupt application of power complicates directional control. Add power with a smooth, uninterrupted motion.
4. Improper use of brakes. Incorrect seat or rudder pedal adjustment, with your feet in an uncomfortable position, frequently causes inadvertent application of brakes and excessive heading changes.
5. Overcontrolling rudder pedals. This fault may be caused by late recognition of heading changes, tension on the controls, misinterpretation of the heading indicator (and correcting in the wrong direction), failure to appreciate changing effectiveness of rudder control as the aircraft accelerates, and other factors. If heading changes are observed and corrected instantly with small movement of the rudder pedals, swerving tendencies can be reduced.
6. Failure to maintain attitude after becoming airborne. If you react to "seat-of-the-pants" sensations when the airplane lifts off, your pitch control is guesswork. You may either allow excessive pitch or apply excessive forward elevator pressure, depending on your reaction to trim changes.
7. Inadequate cross-check. Fixations are likely during trim changes, attitude changes, gear and flap retractions, and power changes. Once you check an instrument or apply a control, continue the cross-check and note the effect of your control during the next cross-check sequence.
8. Inadequate interpretation of instruments. Failure to understand instrument indications immediately indicates that further study of the maneuver is necessary.