How do I use the heading bug and HDG mode in a simulator?

In an aviation flight simulator, set the heading bug to the magnetic heading you want, engage the flight director or autopilot, and select HDG mode. The aircraft will bank to capture and hold that heading. The bug is only a marker; moving it does nothing unless HDG mode is using it.

What do the heading bug and HDG mode do?

The heading bug is a movable reference marker on the heading indicator, HSI or glass-cockpit heading tape. Turning the heading selector moves this marker but does not, by itself, steer the aircraft.

HDG or HDG SEL mode commands the flight director and, when connected, the autopilot to turn towards the selected heading. It then adjusts bank as needed to maintain that heading. If heading, course and bearing are becoming mixed up, our comparison of heading, course and bearing in FSX explains the practical differences.

The selected value is normally a magnetic heading. A setting of 270° points west, while 000° and 360° represent the same direction. Aircraft capable of using true headings may behave differently when that reference is selected, especially at high latitudes.

How do I engage heading mode correctly?

Set and verify the desired heading, make HDG the active lateral mode, then monitor the commanded turn and rollout.

1. Check the heading reference. Confirm that the directional gyro, HSI or PFD shows a valid heading. In aircraft with a conventional directional gyro, align it with the magnetic compass periodically if instrument drift is modelled.
2. Set the heading bug. Rotate the heading selector until the bug or selected-heading readout shows the required value. Set it before connecting the autopilot when possible, preventing an unexpected turn.
3. Consider the turn direction. Most autopilots take the shortest turn towards the bug. If ATC specifies left or right, move the bug progressively around that side when the required direction would otherwise be ambiguous, particularly for a 180° change.
4. Enable the required guidance. A flight director displays steering commands for you to follow manually. The autopilot must be engaged if you expect the aircraft to turn itself, although some simple systems do not have a separate flight director.
5. Select HDG mode. Press the control labelled HDG, HDG SEL or its aircraft-specific equivalent. The order of selecting the mode and connecting the autopilot varies between systems.
6. Confirm the active mode. Check the flight mode annunciator or autopilot panel for an active HDG indication. A lit button is not always proof that the mode is controlling the aircraft.
7. Monitor the turn. Check the initial turn direction, bank angle and rollout. The aeroplane should settle on the selected heading, though turbulence may cause small corrections.

Control layouts differ considerably. Our practical KAP 140 heading-mode procedure covers a conventional general-aviation autopilot, while the guide to G1000 heading controls and mode indications in X-Plane 12 shows how the same logic appears in a glass cockpit.

When should I use HDG instead of NAV or TRK mode?

Use HDG for a pilot-selected direction or an ATC vector; use NAV or LOC when the aircraft must follow a defined lateral path.

For an instrument approach, heading mode is commonly used to fly the intercept vector. Arm NAV or LOC before reaching the course and confirm that it captures. If capture does not occur, the autopilot may remain in HDG and fly straight through the intended path.

Why is the aircraft not following the heading bug?

If the aircraft does not turn towards the bug, the active mode, heading source or autopilot connection is usually wrong.

• HDG is not active: the annunciator may still show NAV, LOC, ROL, CWS or another lateral mode. Trust the active-mode display rather than the button alone.
• Only the flight director is on: command bars will move, but the aircraft will not follow them automatically without the autopilot.
• The bug was synchronised accidentally: pressing some heading knobs copies the present heading into the bug. Rotate it again to the intended value.
• The wrong heading source is coupled: complex aircraft may have separate selectors, navigation sources or pilot-side references. Check which side and source control the autopilot.
• The heading indication is invalid or drifting: realigned conventional instruments and clear any heading or AHRS failure before relying on HDG mode.
• The autopilot has disconnected: excessive control input, an out-of-trim aircraft, low speed or operation outside the system's limits may disconnect it or reduce its ability to follow commands.
• A controller binding is interfering: joystick noise, duplicated assignments or a continuously triggered autopilot command can cancel the mode immediately after selection.

Mode names are not completely standardised. HDG SEL generally follows the bug, but a mode labelled HDG HOLD may capture the aircraft's present heading instead. The aircraft's active-mode indication resolves that distinction.

Why does the ground track differ from the selected heading?

Wind causes the aircraft's ground track to differ from the heading held by the autopilot. HDG mode points the nose at the selected magnetic heading; it does not normally correct that heading to maintain a particular path across the ground.

If ATC assigns a heading, leave the bug on that heading unless instructed otherwise. To follow a programmed route or fixed ground track, use NAV or TRK mode where available rather than manually compensating in HDG.

Can I use the heading bug without the autopilot?

Yes. The heading bug remains useful as a visual reminder when hand-flying: set the required heading, turn towards it and roll out as the aircraft approaches the marker. With the flight director active in HDG mode, follow its command bars while retaining manual control.