Flight Management Systems (FMS)
Flight Management Systems accept inputs from a variety of sensors and provides guidance through all phases of flights to reduce workload.
Introduction
Introduction
- 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 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
Autopilot
Autopilot
- Mechanical means to control an aircraft using electrical, hydraulic, or digital systems
- 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
- Position/attitude based: gyro senses wing position
- Modern systems may combine the above
- Modern autopilots are digital
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Autopilot Use During Climb:
- Use of IAS holds allow for Vx and Vy climbs
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Autopilot Use During Descent:
- Use of VS holds allow for hitting descent planning numbers
-
Autopilot Use in Controlled Airspace:
- Use of functions like IAS hold allow for setting ATC restrictions
Flight Management System Failures
Flight Management System Failures
- Pilots might expect to experience a troublesome autopilot, but not necessarily one that won't disengage
- In the event an autopilot won't disengage, consider alternative means like moving the controls or trim and even pulling the appropriate circuit breaker
Conclusion
Conclusion
- It is good practice to notify the flight deck when autopilot systems are engaged/disengaged
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References
References