Flight Management & Autopilot Systems

Flight Management Systems accept inputs from a variety of sensors and provides guidance through all phases of flights to reduce workload.

Flight Management & Autopilot Systems

Introduction to Flight Management & Autopilot Systems

  • Flight Management Systems (FMS) accept inputs from a variety of sensors and provides guidance through all phases of flights in order to reduce workload
  • Employs a master computer interface
  • A common Control Display Unit (CDU) interfaces with the master computer
  • A pre-loaded database of global navigation information should be accessible to the pilot allowing for a quick flight plan setup (includes NAVAIDS, airways, and intersections, charts, etc.
  • GPS (Global Positioning System) currently a dominate sensor in use today
  • Modern systems utilize Vertical Navigation (VNAV) as well as Lateral Navigation (LNAV)
  • In addition to guidance, FMS' provide information on all systems and conditions of flight such as fuel and weather
  • Test your understanding of Flight Management & Autopilot Systems by applying your knowledge in the interactive scenario, comparing your performance against the applicable Airman Certification Standards, and concluding with the topic summary to reinforce the key concepts before moving on to the next lesson.
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    Flight Management & Autopilot Systems

    Flight Management & Autopilot Systems Key Highlights

    • Flight management and autopilot systems assist pilots with navigation, aircraft control, workload management, and flight automation.
    • Flight Management Systems (FMS) integrate navigation, performance, route planning, and avionics data into a centralized control system.
    • Autopilot systems can maintain heading, altitude, airspeed, navigation tracking, and vertical flight profiles automatically.
    • Modern avionics integrate GPS, RNAV (Area Navigation), autopilot, and electronic flight display systems to improve operational efficiency.
    • Pilots must understand system modes, annunciations, and automation logic to manage automated flight safely.
    • Improper automation management can lead to mode confusion, loss of situational awareness, and operational errors.
    • Pilots remain responsible for monitoring aircraft performance and maintaining overall command authority during automated flight.
    • Autopilot systems may disconnect automatically during system malfunctions, unusual attitudes, or excessive control inputs.
    • Regular cross-checking of flight guidance information and navigation data helps ensure automation accuracy and reliability.
    • Understanding flight management and autopilot systems improves workload management, navigation precision, and overall flight safety.
    Flight Management & Autopilot Systems

    Flight Director/Autopilot

    • Flight directors/autopilot systems provide mechanical means to control an aircraft using electrical, hydraulic, or digital systems.
    • The entire flight director/autopilot system is called an integrated flight control system (IFCS) by some manufacturers; Others may use the term automatic flight control system (AFCS).
    • Autopilots come in three general types:
      • Single-axis, autopilots that only perform a function along a single axis such as a heading hold or wings level.
      • Two-axis, adding elements of pitch control that may permit instrument approach functionality.
      • Three-axis, includes yaw control.
    • Autopilots may be driven by one or a combination of methods:
      • Position/attitude based: gyro senses wing position
        • Uses sensors to determine attitude, etc.
        • Precise, but expensive.
      • Rate-based: turn-and-bank sensor
        • Uses 3 axes of movement and combines information
        • Systems are cheaper, but less sensitive.
      • Accelerometers and AHRS (Attitude and Heading Reference System)
    • Modern systems may combine the above
    • Modern autopilots are digital

    • Autopilot Use During Climb:

      • Use of IAS (Indicated Airspeed) holds allow for Vx and Vy climbs
        • For a climb, IAS or flight-level-change mode generally provides better airspeed protection than vertical-speed mode because the autopilot adjusts pitch to maintain the selected airspeed as available climb performance decreases; a vertical-speed climb requires close airspeed monitoring because the autopilot may progressively increase pitch while airspeed decays.

    • Autopilot Use During Descent:

      • Use of VS holds allow for hitting descent planning numbers
        • For a typical piston-airplane descent, vertical-speed mode generally produces a predictable descent rate while the pilot adjusts power to control airspeed; IAS mode may be preferable when a specific airspeed must be protected, including during turbulence or certain terminal operations.

    • Autopilot Use in Controlled Airspace:

      • Use of functions like IAS hold allow for setting ATC (Air Traffic Control) restrictions
    Flight Management & Autopilot Systems

    Flight Director/Autopilot Controls

    • The FD/AP system may be employed at the following different levels:
      • Off (raw data).
      • Flight director (computed commands).
      • Autopilot.
    • With the system off, the FCI operates as an ordinary attitude indicator.
      • On most FCIs, the command bars are biased out of view when the FD is off.
      • The pilot maneuvers the airplane as though the system were not installed.
    • To maneuver the airplane using the FD, the pilot enters the desired modes of operation (heading, altitude, navigation (NAV) intercept, and tracking) on the FD/AP mode controller.
      • The computed flight commands are then displayed to the pilot through either a single-cue or dual-cue system in the FCI.
      • On a single-cue system, the commands are indicated by "V" bars.
      • On a dual-cue system, the commands are displayed on two separate command bars, one for pitch and one for roll.
      • To maneuver the airplane using computed commands, the pilot "flies" the symbolic airplane of the FCI to match the steering cues presented.
    • On most systems, the FD needs to be operating to engage the autopilot."
      • At any time thereafter, the pilot may engage the autopilot through the mode controller.
        • "
      • The autopilot then maneuvers the airplane to satisfy the computed commands of the FD.
    • Like any computer, the FD/AP system only does what it is told.
      • The pilot should ensure that it has been programmed properly for the particular phase of flight desired.
      • The armed and/or engaged modes are usually displayed on the mode controller or separate annunciator lights.
      • When the airplane is being hand-flown, if the FD is not being used at any particular moment, it should be off so that the command bars are pulled from view.
    • Prior to system engagement, all FD/AP computer and trim checks should be accomplished.
      • Many newer systems cannot be engaged without the completion of a self-test.
      • The pilot should also be familiar with various methods of disengagement, both normal and emergency.
      • System details, including approvals and limitations, can be found in the supplements section of the AFM/POH.
      • Additionally, many avionics manufacturers can provide informative pilot operating guides upon request.
    Flight Management & Autopilot Systems

    Flight Management System Failures

    • Pilots might expect to experience a troublesome autopilot, but not necessarily one that won't disengage
    Flight Management & Autopilot Systems

    Flight Management & Autopilot Systems Interactive Scenario

    Interactive Scenario

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    Flight Management & Autopilot Systems

    Flight Management & Autopilot Systems Lessons & Case Studies

    • National Transportation Safety Board Identification: ENG26LA011:
      • The NTSB determines the probable cause(s) of this incident to be: The elevator control restriction was caused by the failure of an elevator autopilot servo control cable which failed due to cyclic fatigue. The slack in the cable wrapped around the servo mount in such a way that it interfered with the rotation of the servo mount. The servo mount remained connected to the aft side of the elevator control quadrant by the intact aft cables. This condition resulted in the limited rotation of the elevator control quadrant in one direction.
    • National Transportation Safety Board Identification: ENG25LA009:
      • The NTSB determines the probable cause(s) of this incident to be: The elevator control restriction was caused by the failure of the elevator autopilot servo control cable, which failed due to cyclic fatigue. The slack in the broken cable wrapped around the elevator autopilot servo mount in such a way that it was bound between the servo mount and the servo mount cable guide pins. The bound cable interfered with the rotation of the servo mount, which remained connected to the aft side of the elevator control quadrant by the intact aft cables. This condition resulted in the limited rotation of the elevator control quadrant in one direction.
    • National Transportation Safety Board Identification: WPR24FA124:
      • The NTSB determines the probable cause(s) of this accident to be: The pilot’s continued use of the airplane’s autopilot after flight into moderate to severe icing conditions, which resulted in an exceedance of the airplane’s critical angle of attack and an aerodynamic stall.
    • National Transportation Safety Board Identification: CEN23FA190:
      • The NTSB determines the probable cause(s) of this accident to be: The pilot’s poor preflight decision to depart into known instrument meteorological conditions (IMC) without a functional autopilot system, which resulted in spatial disorientation and his failure to maintain aircraft control while flying in IMC during the instrument approach. Contributing to the accident was the pilot’s self-imposed pressure to conduct the flight.
    • National Transportation Safety Board Identification: ERA23LA135:
      • The NTSB determines the probable cause(s) of this accident to be: The flight crew’s failure to remove the right side pitot probe cover before flight, their decision to depart with a No-Go advisory message following an aborted takeoff, and their selection of the incorrect non-normal checklist in flight, which resulted in an in-flight upset that exceeded the maneuvering load factor limitations of the airplane and resulted in fatal injuries to a passenger whose seatbelt was not fastened. Contributing to the severity of the in-flight upset were the pilot-in-command’s (PIC) decision to continue the climb and use the autopilot while troubleshooting the non-normal situation, and the PIC’s pilot-induced oscillations following the autopilot disconnecting from the out-of-trim condition. Also contributing to the accident was the crew’s inadequate crew resource management.
    • National Transportation Safety Board Identification: WPR23MA113:
      • The NTSB determines the probable cause(s) of this accident to be: The pilot’s loss of control due to spatial disorientation while operating in night instrument meteorological conditions, which resulted in an in-flight breakup. Contributing to the accident was the disengagement of the autopilot for undetermined reasons, as well as the operator’s insufficient flight risk assessment process and lack of organizational oversight.
    • National Transportation Safety Board Identification: CEN23FA045:
      • The NTSB determines the probable cause(s) of this accident to be: The uncommanded activation of the CAPS autopilot mode due to corrosion of the system’s electrical components. Contributing to the accident was the pilot’s failure to identify the CAPS autopilot mode and promptly follow the procedures in the airplane flight manual.
    • NTSB Identification: DCA13MA120
      • NTSB report summary: Asiana Flight 214 struck the seawall while approaching San Francisco in visual conditions. The report identifies descent management, unintended deactivation of automatic airspeed control, inadequate airspeed monitoring, and a delayed go-around among the causes. Consult the linked report for the full findings and contributing factors.
    Flight Management & Autopilot Systems

    Flight Management & Autopilot Systems Conclusion

    • Autopilots, navigation systems, and automation in general is only as helpful and can only enhance situational awareness and safety if the pilot knows how to use and interpret it's data.
      • Pilots must take the time to understand their systems, as they can differ significantly from airplane to airplane.
      • Understand the autopilot's operating limitations, know when it will engage or disengage, and practice the applicable procedures.
      • Periodically practice appropriate training tasks without automation or moving-map guidance so that basic aircraft control, pilotage, navigation-radio use, flight planning, and workload-management skills remain available if electronic equipment fails.
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    Flight Management & Autopilot Systems References