Learn to use the Boeing 737 autopilot in a flight simulator, including MCP setup, LNAV/VNAV, descent, ILS capture and common fixes.
To use the Boeing 737 autopilot in a flight simulator, switch on both flight directors, arm the autothrottle if required, set MCP speed, heading and altitude, then engage CMD after take-off. Select a lateral and vertical mode, and confirm every engagement on the Flight Mode Annunciator rather than trusting button lights alone.
For Aviation & Real-World Flying accuracy, treat the 737 autopilot as a mode-based system rather than an automatic pilot that decides where to go. The Mode Control Panel (MCP) supplies targets, while the Flight Management Computer (FMC) supplies the route and calculated vertical profile. The autopilot does not normally taxi or take off for you.
Button names are broadly consistent across simulated 737 NG and MAX aircraft, but system depth varies. Simplified models may omit Control Wheel Steering, dual-channel approaches or parts of the real engagement logic.
How do I engage the 737 autopilot after take-off?
Engage CMD only after the aircraft is airborne, stable and correctly trimmed, at or above the minimum engagement height represented by the aircraft. A common procedural minimum is about 400 feet above ground after take-off, although the exact restriction depends on the model and operating procedure.
- Prepare the FMC. If you intend to use LNAV or VNAV, enter and check the route, departure, cruise altitude, performance data and take-off settings. Follow our detailed 737 FMC programming sequence if the route or performance pages are unfamiliar.
- Set the MCP. Enter the initial speed, heading and cleared altitude. Set the course selectors when a departure or approach requires them.
- Switch on the flight directors. Standard operation uses both flight director switches. Arm the autothrottle when the procedure calls for it.
- Take off manually. Use the flight director guidance, establish a safe climb, retract the landing gear and follow the required flap schedule. Arm or select LNAV, HDG SEL, VNAV or another suitable mode as required.
- Engage one CMD channel. Press CMD A or CMD B once the aircraft is stable and there is no sustained pressure on the controls. One channel is sufficient for ordinary climb, cruise and descent.
- Read the FMA. Confirm the active roll, pitch and autothrottle modes immediately. If the annunciation is not what you expected, correct the mode selection before attending to another task.
Do not engage both CMD channels for normal flight. The second channel is associated with a properly configured dual-channel ILS approach or autoland, and many basic simulator aircraft do not model that function fully.
Which Boeing 737 autopilot mode should I use?
Choose the mode according to the guidance you need: LNAV or HDG SEL for direction, and VNAV, LVL CHG, V/S or ALT HLD for vertical control.
| Mode | Use it when | Main caution |
|---|---|---|
| LNAV | Following the active FMC route | The route must be valid, active and within suitable capture geometry. |
| HDG SEL | Following an ATC heading or positioning for an intercept | The aircraft turns towards the heading shown in the MCP heading window. |
| VNAV | Following the FMC climb, cruise or descent profile | It needs complete performance data, and the MCP altitude acts as a clearance limit. |
| LVL CHG | Making a direct climb or descent at a selected speed | Pitch controls speed while thrust normally moves towards climb thrust or idle. |
| V/S | Using a specific vertical rate for a modest climb or descent | An excessive rate can exhaust available thrust or produce an overspeed. Watch airspeed continuously. |
| ALT HLD | Maintaining the present or captured altitude | It will not start a climb or descent simply because a different altitude is set. |
| VOR/LOC or APP | Capturing localiser or complete ILS guidance | Correct tuning, course, intercept geometry and an approach signal are required. |
LVL CHG is usually the clearest choice for an immediate climb or descent while controlling speed. V/S is useful when a gentle, specific rate is needed, but it demands closer speed monitoring. VNAV is appropriate when the FMC route and performance data are complete and you want the calculated profile.
Why is the Flight Mode Annunciator so important?
The Flight Mode Annunciator tells you what the 737 is actually doing; MCP lights show only what has been selected or armed. On the PFD, active modes normally appear in green and armed modes in white, with autothrottle, roll and pitch modes displayed across the top.
Setting 10,000 feet in the altitude window does not itself command a descent. The FMA must show an active descending mode such as VNAV PTH, LVL CHG or V/S. If it still shows ALT HLD, the aircraft will remain level.
A mistake we see constantly is pressing several mode buttons and then watching the controls instead of the FMA. Make one selection, verify the new annunciation, then continue. If the display shows CWS P or CWS R, the autopilot is in Control Wheel Steering rather than following a normal pitch or roll command mode.
How do I use the 737 autopilot for descent and landing?
For descent, set the cleared lower altitude in the MCP and select a suitable vertical mode. VNAV will normally remain level at the MCP altitude or fail to begin its planned descent if the altitude window has not been lowered; LVL CHG starts a more direct speed-controlled descent, while V/S gives you a chosen rate.
Speed restrictions, the MCP altitude and FMC constraints can interact in ways that are not obvious from the MCP alone. Our 737 descent and approach setup explains when to use VNAV, LVL CHG and manual speed intervention.
For an ILS, tune and identify the approach where the simulated aircraft does not do so automatically, set the published course, approach on a sensible intercept and capture the localiser before the glide slope. APP mode arms both localiser and glide-slope capture; it does not rescue an aircraft approaching from above the glide slope or at an unsuitable angle. Use the complete 737 ILS capture sequence for the required mode order and autoland conditions.
For a manual landing, disconnect the autopilot with enough time to stabilise your hand flying and trim. The autothrottle may remain active after autopilot disconnection, so disconnect it separately if you want full manual thrust control. On typical 737 logic, the first autopilot-disconnect input disengages the system and the second silences the warning.
Why will the 737 autopilot not engage or follow the route?
Most 737 autopilot failures in a simulator come from an invalid FMC route, unsuitable capture geometry, an MCP restriction, control-axis noise or a missed FMA annunciation rather than a broken system.
- CMD will not engage: check that the autopilot disengage bar is up, the aircraft is above the permitted height, electrical and hydraulic systems are available, and the controls are close to neutral. Trim the aircraft instead of holding continuous yoke pressure.
- CMD disconnects immediately: remove duplicate controller assignments and increase a noisy axis dead zone slightly. A mapped disconnect switch, severe out-of-trim condition or modelled system failure can also cause repeated disconnections.
- LNAV will not engage: activate and verify the FMC route, remove route discontinuities and intercept the active leg from a reasonable position and heading.
- VNAV will not engage: complete the route and performance pages, check for missing cruise altitude or speed data, and look for an invalid or discontinuous flight plan.
- VNAV will not descend: lower the MCP altitude when cleared and verify that the aircraft has reached the calculated descent point. An altitude constraint may also be holding the aircraft level.
- The aircraft turns or climbs unexpectedly: read the active FMA modes and compare them with the MCP and FMC. HDG SEL may still be active instead of LNAV, or LVL CHG may be targeting an unintended MCP altitude.
- APP does not capture: confirm the ILS frequency, course and identifier, then intercept the localiser at a moderate angle from below the glide slope.
If LNAV or VNAV remains unavailable after those checks, work through the specific checks for failed 737 LNAV and VNAV engagement. Avoid repeatedly pressing the same button: the FMA and FMC messages normally reveal which condition is missing.