Common Errors in Straight-and-Level Flight
Pitch errors usually result from the following faults:
- Improper adjustment of the attitude indicator’s miniature aircraft to the wings-level attitude. Following the initial level off from a climb, check the attitude indicator and make any necessary adjustment in the miniature aircraft for level flight indication at normal cruise airspeed.
- Insufficient cross-check and interpretation of pitch instruments. For example, the airspeed indication is low. The pilot, believing a nose-high attitude exists, applies forward pressure without noting that a low power setting is the cause of the airspeed discrepancy. Increase cross-check speed to include all relevant instrument indications before making a control input.
- Uncaging the attitude indicator (if caging feature is present) when the airplane is not in level flight. The altimeter and heading indicator must be stabilized with airspeed indication at normal cruise before pulling out the caging knob to obtain correct indications in straight-and-level flight at normal cruise airspeed.
- Failure to interpret the attitude indicator in terms of the existing airspeed.
- Late pitch corrections. Pilots commonly like to leave well enough alone. When the altimeter indicates a 20 foot error, there is a reluctance to correct it, perhaps because of fear of overcontrolling. If overcontrolling is the anticipated error, practice small corrections and find the cause of overcontrolling. If any deviation is tolerated, errors increase.
- Chasing the vertical speed indications. This tendency can be corrected by proper cross-check of other pitch instruments, as well as by increasing overall understanding of instrument characteristics.
- Using excessive pitch corrections for the altimeter evaluation. Rushing a pitch correction by making a large pitch change usually aggravates the existing error, saving neither time nor effort.
- Failure to maintain established pitch corrections, a common error associated with cross-check and trim errors. For example, having established a pitch change to correct an altitude error, there is a tendency to slow down the cross-check, waiting for the airplane to stabilize in the new pitch attitude. To maintain the attitude, continue to cross-check and trim off the pressures.
- Fixations during cross-check. After initiating a heading correction, for example, there is a tendency to become preoccupied with bank control and miss errors in pitch attitude. Likewise, during an airspeed change, unnecessary gazing at the power instrument is common. A small error in power setting is of less consequence than large altitude and heading errors. The airplane will not decelerate any faster by staring at the manifold pressure gauge.
Heading errors usually result from the following faults:
- Failure to cross-check the heading indicator, especially during changes in power or pitch attitude.
- Misinterpretation of changes in heading, with resulting corrections in the wrong direction.
- Failure to note and remember a preselected heading.
- Failure to observe the rate of heading change and its relation to bank attitude.
- Overcontrolling in response to heading changes, especially during changes in power settings.
- Anticipating heading changes with premature application of rudder control.
- Failure to correct small heading deviations. Unless zero error in heading is the goal, a pilot will tolerate larger and larger deviations. Correction of a 1 degree error takes a lot less time and concentration than correction of a 20° error.
- Correcting with improper bank attitude. If correcting a 10° heading error with 20° of bank, the airplane rolls past the desired heading before the bank is established, requiring another correction in the opposite direction. Do not multiply existing errors with errors in corrective technique.
- Failure to note the cause of a previous heading error and thus repeating the same error. For example, the airplane is out of trim, with a left wing low tendency. Repeated corrections for a slight left turn are made, yet trim is ignored.
- Failure to set the heading indicator properly or failure to uncage it.
Power errors usually result from the following faults:
- Failure to know the power settings and pitch attitudes appropriate to various airspeeds and airplane configurations.
- Abrupt use of throttle.
- Failure to lead the airspeed when making power changes. For example, during airspeed reduction in level flight, especially with gear and flaps extended, adjust the throttle to maintain the slower speed before the airspeed actually reaches the desired speed. Otherwise, the airplane decelerates to a speed lower than that desired, resulting in additional power adjustments. The amount of lead depends upon how fast the airplane responds to power changes.
- Fixation on airspeed or manifold pressure instruments during airspeed changes, resulting in erratic control of both airspeed and power.
Trim errors usually result from the following faults:
- Improper adjustment of seat or rudder pedals for comfortable position of legs and feet. Tension in the ankles makes it difficult to relax rudder pressures.
- Confusion about the operation of trim devices that differ among various airplane types. Some trim wheels are aligned appropriately with the airplane’s axes; others are not. Some rotate in a direction contrary to what is expected.
- Faulty sequence in trim technique. Trim should be used not as a substitute for control with the wheel (stick) and rudders, but to relieve pressures already held to stabilize attitude. As proficiency is gained, little conscious effort is required to trim off the pressures as they occur.
- Excessive trim control. This induces control pressures that must be held until the airplane is trimmed properly. Use trim frequently and in small amounts.
- Failure to understand the cause of trim changes. Lack of understanding the basic aerodynamics related to basic instrument skills causes a pilot to continually lag behind the airplane.