How do heading, course and bearing work in FSX?

In FSX and FSX: Steam Edition, heading is where the aircraft’s nose points, course is the intended ground path or the radio-navigation line selected with CRS/OBS, and bearing is the direction to or from a point. HDG controls a heading bug; CRS sets navigation guidance, not the aircraft’s nose.

These principles are the same in boxed FSX and FSX: Steam Edition. Add-on aircraft may have different knobs, source selectors and autopilot logic, but the underlying definitions do not change.

Bearing vs course vs heading — and where track fits

Heading describes the aircraft’s orientation, course describes a desired line, bearing connects two positions, and track describes the aircraft’s actual movement over the ground.

Directions are measured clockwise from north: 000° or 360° is north, 090° is east, 180° is south and 270° is west. FSX cockpit instruments normally use magnetic directions unless a display explicitly says otherwise.

Wind explains many apparent contradictions. An aircraft following an easterly course or track of 090° in a wind from the north might need a heading of roughly 085°. The nose points north of the desired path so the wind does not push the aircraft south of it.

CRS vs HDG: what is the difference?

HDG selects where you want the nose pointed, while CRS selects the navigation line you want to intercept or track.

• HDG knob: Moves the heading bug. The aircraft follows it only when the autopilot is engaged in HDG mode; otherwise, it is simply a visual reference for hand flying.
• CRS or OBS knob: Rotates the selected course on a VOR indicator, CDI or HSI. It affects how course deviation is presented, but it does not command a turn by itself.
• Bearing: Usually has no control knob because it is a measured direction. The bearing changes as the aircraft or destination moves.

A mistake we see often is reading the heading bug as the aircraft’s present heading. The current heading is read against the instrument’s fixed lubber line; the bug is only the selected target. Our guide to setting the heading bug and using autopilot HDG mode explains how the selection and active lateral mode work together.

Moving the heading bug may have no effect while NAV or APPR is active. Likewise, changing CRS does not make the aircraft turn unless an appropriate navigation mode is engaged and valid guidance is available. Check the autopilot’s active mode rather than assuming the most recently pressed button has control.

How do I use HDG and CRS together in FSX?

Use HDG to establish an intercept heading, then use CRS with NAV or APPR mode to capture and follow the selected navigation line.

1. Select the navigation source. Choose the appropriate NAV receiver for a VOR or ILS. Choose GPS when following an active GPS flight-plan leg on a panel with a NAV/GPS source selector.
2. Tune and identify the station. Put the VOR or ILS frequency in the correct receiver and confirm its identifier before trusting the needle. See our practical instructions for tuning NAV1 and interpreting its CDI guidance.
3. Set the desired course. Rotate CRS or OBS to the intended inbound course, outbound course or published localiser front course.
4. Choose an intercept heading. Use the heading bug and HDG mode to approach the course at a useful angle. Flying parallel to a displaced course will not intercept it.
5. Select the tracking mode. Use NAV for VOR or GPS tracking. Use APPR for an ILS on an aircraft whose autopilot supports localiser and glideslope capture.
6. Monitor the capture. Watch the CDI and mode indication. If the needle crosses the centre while the aircraft remains in HDG mode, NAV or APPR did not capture.

The autopilot is not a substitute for a sensible intercept. A weak or invalid signal, the wrong source, excessive displacement or poor intercept geometry can prevent capture. Glideslope capture also depends on the aircraft and autopilot; normally the aircraft should intercept it from below rather than descending through it from above.

What does the course selector do with VOR, ILS, GPS and ADF?

The effect of the CRS or OBS selector depends on the navigation source connected to the instrument.

• VOR: CRS selects an inbound or outbound course and the CDI shows displacement from that line. Radials are named in the direction from the station. If you are west of a VOR and want to fly inbound on 090°, select 090° with a TO indication; the aircraft is approaching along the station’s 270° radial.
• ILS: Set the published front course for correct orientation on an HSI and for any aircraft systems that use the selected course. The localiser transmitter defines the centreline, so rotating CRS cannot move it. On a basic VOR/ILS indicator, changing OBS may not alter localiser needle displacement at all.
• GPS: During normal leg sequencing, the active GPS leg supplies the desired track. Turning CRS may do nothing unless the fitted GPS or add-on avionics provide an OBS-style mode. The panel must also be using GPS rather than NAV as its guidance source.
• ADF/NDB: An ADF needle indicates bearing to the NDB and does not use VOR-style CRS selection. A rotatable ADF compass card may be aligned with the aircraft heading, but rotating that card does not change the bearing or command a course. Our guide to VOR tracking and NDB bearing techniques covers interception, tracking and wind correction.

Can you set bearing in FSX?

Bearing is normally read from an instrument rather than set by the pilot.

On a fixed-card ADF, the needle shows relative bearing clockwise from the aircraft’s nose. To estimate magnetic bearing to the station, add magnetic heading and relative bearing, then subtract 360° if necessary. With a heading of 070° and relative bearing of 040°, the magnetic bearing to the station is approximately 110°.

An RMI uses a heading card, so the needle head normally shows magnetic bearing to the station directly. Its tail shows the reciprocal bearing from the station. A slaved HSI may combine present heading, selected course, course deviation and separate bearing pointers; our detailed explanation of reading heading, course and bearing information on an HSI shows how to keep those indications separate.

Keeping an ADF needle on the nose is called homing. In a crosswind it produces a curved ground path towards the beacon. Tracking an NDB requires a wind-corrected heading that holds the required course instead.

Why do heading, course and bearing disagree?

Heading, course and bearing disagree when wind, intercept geometry, instrument references or navigation sources make them describe different directions.

• Wind: Heading must be offset into the wind to maintain the desired course and track.
• Interception: Heading should differ from CRS while joining a VOR radial or localiser.
• Changing geometry: Bearing points directly towards a station or waypoint. It need not match the planned course unless the aircraft is established on that direct line.
• Relative versus magnetic bearing: A fixed-card ADF gives an angle from the nose, while an RMI normally gives a direction from magnetic north.
• Different sources: The CDI may be connected to NAV1 while the autopilot is following GPS, or the expected signal may be tuned in NAV2.
• True versus magnetic direction: A map, planner or external reference may use a different north reference. FSX also uses magnetic and navigation data from its own data set, so modern real-world charts can show different figures.
• Gyro drift: If gyro drift is enabled, an unslaved heading indicator can gradually disagree with the magnetic compass. Synchronise it in straight, steady flight using the assigned heading-indicator adjustment or reset control.

Common FSX mistakes and their fixes

Most apparent instrument failures are caused by an inactive mode, wrong source or misunderstood indication rather than a broken gauge.

Which value should I use?

Choose the value according to what you need the aircraft or navigation system to do.

• Use heading and the HDG bug for ATC vectors, manual steering references and course interceptions.
• Use course and CRS/OBS for a VOR radial, localiser front course or other defined navigation line.
• Use bearing to determine where a station or waypoint lies relative to the aircraft.
• Use track to check where the aircraft is actually moving over the ground and whether the wind correction is working.