Straight & Level Flight

Introduction:

  • Straight and level flight is flight in which a constant heading and altitude are maintained
  • Used during cross-countries when flying from point A to point B
  • Accomplished by making immediate and measured corrections for deviations in pitch, bank, and power
  • Fundamental flight maneuver which all other flight maneuvers are in essence a deviation from
  • When done correctly the airspeed will remain constant, the attitude indicator will be level, the altimeter will not move, the turn coordinator will read wings level with the ball in the center, the heading indicator will not move and the vertical speed indicator will indicate no climb
  • All forces are equal during unaccelerated flight

WARNING:
All procedures are GENERALIZED.
Fly the maneuver in accordance with the Pilot Operating Handbook (POH)
and/or current Standard Operating Procedures (SOPs)


Pitch Control:

  • Pitch is the angle between longitudinal axis and actual horizon

  • Attitude Indicator:

    • Direct indication of pitch
    • Supporting pitch indicator

  • Altimeter:

    • Primary pitch instrument
    • For errors of 100' or less, use half-bar width
    • For errors more than 100', use full-bar width initially, until within 100'
    • Over-controlling occurs when excessive corrections are applied

  • Vertical Speed Indicator:

    • Indirect indicator of trend and rate
    • Lag characteristics must be considered
    • Make attitude changes that will result in a vertical speed approximately double your error in altitude
    • Supporting pitch indicator

  • Airspeed Indicator:

    • Indirect indication of pitch
    • Constant pitch will result in constant airspeed, when stable

Bank Control:

  • The angle between the lateral axis (wingspan) and the natural horizon is bank

  • Attitude Indicator:

    • Directly and instantly shows changes in bank however it is considered a supporting bank instrument

  • Heading Indicator:

    • Primary bank indication instrument

  • Turn Coordinator:

    • Indirect indication of bank, supporting the same as the attitude indicator
    • Ball centered = straight and level
    • Ball right = right wing low, in a right turn
    • Ball left = left wing low, in a left turn
    • Ball indicators display the quality of turn (coordination)
    • Wings level with any deflection equals a skid

Power Control:

  • Thrust is created to overcome the forces of gravity and drag
  • Altitude and airspeed determine changes of pitch or power
  • Power Settings:
    • The airspeed indicator is the primary power instrument which will be thrown out of balance in under/over power conditions
    • Manifold Pressure (MP) and Tachometer instruments are primary instruments to set power, secondary once stable

Straight and Level Flight Procedure:

  1. Perform clearing turns
  2. Pick a reference point
    • The farther the better to prevent movement
    • Be sure to be sitting "normal" when picking a point
    • This point should not move in your "picture"
  3. Maintain pitch attitude
    • Set pitch so the reference point is motionless
    • Note the picture (horizon relative to dashboard)
    • The "finger" trick may also be used to judge distance from the horizon to the glare shield
  4. Glance at the instruments to see if the airplane is flying level
    • Corrections should be made with the elevator (light grip)
    • Adjust the pitch slowly making minor changes at a time
  5. Adjust trim
  6. Cross check instruments
  7. Maintain straight flight
    • Check the wingtips with the horizon, they should be equidistant with the horizon (above is high wing, below if low wing)
  8. Glance at the heading indicator to verify straight flight
    • Corrections should be made with the ailerons (light grip)
    • Check aircraft coordination in the turn coordinator
  9. Complete cruise checklist

Instrument Reference:

  • For any maneuver of condition of flight, the pitch, bank, and power control requirements are most clearly indicated by certain key instruments
  • Those instruments which provide the most pertinent and essential information will be referred to as primary instruments
  • Supporting instruments back up and supplement the information shown on the primary instruments
PITCH BANK POWER
Primary Altimeter Heading Indicator Airspeed Indicator
Supporting Attitude / VSI Attitude / Turn Coordinator MP and/or RPM

Straight and Level Flight Common Errors:

  • Failure to adequately clear the area, as appropriate
  • Attempting to use improper reference points on the airplane to establish attitude
  • Forgetting the location of pre-selected reference points on subsequent flights
  • Attempting to establish or correct airplane attitude using flight instruments rather than outside visual reference
  • Attempting to maintain direction using only rudder control
  • Habitually flying with one wing low
  • "Chasing" the flight instruments rather than adhering to the principles of attitude flying
  • Too tight a grip on the flight controls resulting in over control and lack of feel
  • Nudging the flight controls when performing other tasks
  • Pushing or pulling on the flight controls rather than exerting pressure against the air stream
  • Improper scanning and/or devoting insufficient time to outside visual reference (head in the cockpit)
  • Fixation on the nose (pitch attitude) reference point
  • Unnecessary or inappropriate control inputs
  • Failure to make timely and measured control inputs when deviations from straight-and-level flight are detected
  • Inadequate attention to sensory inputs in developing feel for the airplane
  • Over control the aircraft with trim adjustments
  • Un-caging the attitude indicator when the airplane is not in level flight
  • Insufficient cross-check and interpretation
  • Improper adjustment of the attitude indicator's miniature aircraft to the wing-level attitude
  • Heading:
    • 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 pre-selected heading
    • Failure to observe the rate of heading change and its relation to bank attitude
    • Over-controlling 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° 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 will roll 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 un-cage it
  • Power:
    • 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 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 will decelerate to speed lower than that desired, resulting in additional pitch adjustments. THe amount of lead depends on 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:
    • Improper adjustment of seat or rudder pedals for comfortable position of legs and feet. Tension in the angles makes it difficult to relax rudder pressures
    • Confusion about the operation of trim devices, which differ among various airplane types. Some trim wheels are aligned appropriately with the airplane's axis; 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 will be required to trim off the pressures as they occur
    • Excessive trim control. This induces control pressure 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 will cause a pilot to continually lag behind the airplane

Private Pilot - Straight-and-Level Flight Airman Certification Standards:


Private Pilot (Airplane) Straight-and-Level Flight Knowledge:

The applicant demonstrates understanding of:

  • PA.VIII.A.K1:

    Flight instruments as related to:
    • PA.VIII.A.K1a:
      Instrument limitations and potential errors.
    • PA.VIII.A.K1b:
      Indication of the aircraft attitude.
    • PA.VIII.A.K1c:
      Function and operation.
    • PA.VIII.A.K1d:
      Proper instrument cross-check techniques.

Private Pilot (Airplane) Straight-and-Level Flight Risk Management:

The applicant is able to identify, assess, and mitigate risk associated with:

  • PA.VIII.A.R1:

    Instrument flying hazards, including failure to maintain visual flight rules (VFR), spatial disorientation, loss of control, fatigue, stress, and emergency off airport landings.

  • PA.VIII.A.R2:

    When to seek assistance or declare an emergency in a deteriorating situationn.

  • PA.VIII.A.R3:

    Collision hazards.

  • PA.VIII.A.R4:

    Distractions, task prioritization, loss of situational awareness, or disorientation.

  • PA.VIII.A.R5:

    Fixation and omission.

  • PA.VIII.A.R6:

    Instrument Interpretation.

  • PA.VIII.A.R7:

    Control application solely by reference to instruments.

  • PA.VIII.A.R8:

    Trimming the aircraft.

Private Pilot (Airplane) Straight-and-Level Flight Skills:

The applicant exhibits the skill to:

  • PA.VIII.A.S1:

    Maintain straight-and-level flight using proper instrument cross-check and interpretation, and coordinated control application.

  • PA.VIII.A.S2:

    Maintain altitude ±200 feet, heading ±20°, and airspeed ±10 knots.

Conclusion:


References: