I did a quick summary for the 737 and A320 autopilot. Any advice to improve or clarifications?
I know it’s super-brief, but I figured that it would potentially help knowing what does what without explicitly listing pages and pages of procedures for each mode.
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737 Autopilot
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Autopilot Parameter Selectors
- Course Selector: Sets course in COURSE display for related VHF NAV receiver.
- IAS MACH Selector: Sets speed input to aircraft autopilot.
- C/O: Change over airspeed unit (IAS (indicated airspeed) vs Mach), usually used above FL260, or 26000 ft
- Heading Selector: Sets heading input to aircraft autopilot.
- Altitude Selector: Sets altitude input to aircraft autopilot.
- Vertical Speed Selector: Sets vertical speed input to aircraft autopilot.
Autopilot, Flight Director & Autothrottle Selectors
- Auto-throttle (A/T) ARM Switch : Arms A/T for engagement. Auto-throttle engages automatically when LVL CHG, V/S, VNAV, ALT HOLD modes are used.
- Flight Director (F/D) Switch: Arms flight director
- CMD A/B: Engages autopilot in selected mode.
- CWS A/B: Control Wheel Steering. Used as an “attitude hold” (CWS R = Roll Angle Maintained, CWS P = Pitch Angle Maintained)
- DISENGAGE Bar: Disengages autopilot.
Autoflight – Thrust/Speed Modes
- N1: Engages auto-throttle in N1 mode maintains thrust at N1 limit selected from FMC (or manually set via the N1 Set knob). Automatically engages in certain conditions.
- SPD: Engages auto-throttle in SPEED mode (maintains IAS/MACH value in display).
Autoflight – Vertical Modes
- VNAV: Vertical Navigation mode will follow the vertical components and restrictions of the flight plan entered in the FMC.
- LVL CHG (Level Change): Aircraft climbs or descends to selected ALTITUDE at selected IAS/MACH
- SPD INTV: Speed Intervention, aircraft limits its speed to selected IAS/MACH. Used while in VNAV mode. Used for speeds not set in FMC flight plan restrictions.
- ALT HLD: Aircraft levels off and holds its current altitude.
- V/S: Sets Vertical Speed to selected VERT SPEED.
- ALT INTV: Altitude Intervention, aircraft will climb or descend to selected ALTITUDE. Used for altitudes not set in FMC flight plan restrictions.
Autoflight – Lateral Modes
- LNAV: Lateral Navigation mode will follow the lateral components and restrictions of the flight plan entered in the FMC.
- HDG SEL: Heading and Bank Angle selector. Aircraft will roll towards the selected HEADING.
- VOR LOC: Tracks VHF Ominidirectional Range (VOR) localizer. Aircraft will only be controlled laterally.
Autoflight – Vertical + Lateral Mode
- APP: Tracks localizer and glideslope during approach. Aircraft will be controlled laterally and vertically.
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A320 Autopilot
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Autopilot Parameter Selectors
Tip: When pulling a knob, it’s YOUR aircraft (selected input will drive autopilot). When pushing a knob, the FMGS takes over (managed aircraft flight plan will drive autopilot).
- SPD MACH: Change over airspeed unit (IAS (indicated airspeed) vs Mach), usually used above FL260, or 26000 ft
- METRIC ALT: Toggles altitude unit system (metric vs imperial)
- SPEED Selector: When pulled, autopilot and auto-throttle will set the aircraft at the selected speed. When pushed, autopilot and auto-throttle will set the aircraft at the managed speed of the FMGS (flight plan).
- HEADING Selector: When pulled, autopilot and auto-throttle will set the aircraft at the selected heading. When pushed, autopilot and auto-throttle will set the aircraft at the managed heading of the FMGS (flight plan).
- ALTITUDE Selector: When pulled, autopilot and auto-throttle will set the aircraft at the selected altitude. When pushed, autopilot and auto-throttle will set the aircraft at the managed altitude of the FMGS (flight plan). Note that the autopilot will not go below waypoint altitude restrictions (in magenta on PFD altitude tape) in managed mode, while in selected mode it will ignore such restrictions (i.e. if you get clearance from an Air Traffic Controller).
- VERTICAL SPEED Selector: When pulled, aircraft will follow vertical speed selected. When pushed, aircraft will level off.
Note: These speed, heading, altitude and vertical speed autopilot commands can be combined together. It is very important to know whether you set them in “managed” (the FMGS flight plan restrictions drive the autopilot) or “selected” (your selected value drives the autopilot) mode.
Autopilot, Flight Director & Autothrottle Selectors
- Autothrottle (A/THR) ARM Switch : Arms A/T for engagement. Autothrottle engages automatically.
- Flight Director (FD) Switch: Arms flight director
- AP 1/2: Engages autopilot in selected mode.
Autoflight – Vertical Modes
- EXPED: Engages EXPED mode to reach the altitude window with maximum vertical gradient.
Autoflight – Lateral Modes
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- LOC: Tracks VHF Ominidirectional Range (VOR) localizer. Aircraft will only be controlled laterally. Used in case the ILS system is unserviceable.
- NOTE: LS is not an autopilot mode. Pressing this button displays ILS (Instrumented Landing System) information on the PFD.
Autoflight – Vertical + Lateral Mode
- APPR: Tracks localizer and glideslope during approach. Aircraft will be controlled laterally and vertically.