What should you do if the heading indicator fails in flight?
Heading indicator failed in flight? Learn how to confirm the fault, fly partial panel, handle VFR or IFR, use ATC and decide when to land.
In real-world aviation, if the heading indicator fails in flight, keep the aircraft under control, confirm the fault against the magnetic compass and independent instruments, then disregard the faulty display. Use visual references or partial-panel techniques, follow the aircraft checklist, advise ATC if IFR, and land if safe operation is in doubt.
Immediate actions after a heading indicator failure
Treat a suspect heading indicator, also called a directional gyro or DI, as failed until an instrument cross-check shows that it is merely mis-set.
- Fly the aircraft. Hold a safe attitude, airspeed and altitude using reliable instruments and outside references. If workload is high, stabilise in straight-and-level flight before troubleshooting.
- Cross-check the indication. Compare it with the magnetic compass, attitude indicator, turn coordinator and available navigation information. Make this comparison in steady, unaccelerated flight because the magnetic compass has turning and acceleration errors.
- Stop following the suspect instrument. A slowly drifting, frozen or spinning heading indication can tempt a pilot into an unnecessary turn. Remove it from the active scan once the fault is confirmed.
- Use the aircraft checklist. The approved flight manual or pilot's operating handbook determines which alternative instruments, power sources or reversionary modes are available. Do not reset a circuit breaker repeatedly or change electrical configurations unless the procedure authorises it.
- Reduce the risk. Stay out of cloud if VFR, advise ATC if receiving a service, and divert when weather, terrain, darkness or additional failures make continued flight unsafe.
How do you confirm that the heading indicator has failed?
A failed heading indicator disagrees persistently with independent references; a correctly operating mechanical gyro may only need routine realignment with the magnetic compass.
| Indication | Likely explanation | Response |
|---|---|---|
| Small error that increases gradually | Normal gyro precession, incorrect initial setting or excessive drift | Realign in straight, unaccelerated flight if the checklist permits. Review normal gyro precession and compass synchronisation. |
| Display is frozen, tumbling or changing rapidly | Gyro, instrument or data failure | Disregard it and use independent directional references. |
| Heading and attitude indications fail together | Possible shared vacuum, electrical or data-source failure | Move immediately to the remaining independent instruments and apply the relevant system-failure checklist. |
| HDG, AHRS or comparator warning appears on a glass display | Magnetometer, AHRS, display or data-source fault | Select an approved alternate source or standby display, but only if it does not depend on the same failed source. |
Many conventional aircraft use vacuum power for both the heading indicator and attitude indicator, although installations vary and either instrument may instead be electrically driven. Knowing which instruments a vacuum fault can take with it prevents the dangerous assumption that the attitude indicator remains reliable.
On a glass cockpit, changing screens may not solve the problem. Two displays can show the same incorrect heading because both receive data from one AHRS or magnetometer. Check source annunciations and the genuinely independent standby instruments.
What changes between VFR and IFR?
A single heading indicator failure is usually manageable in visual conditions, but it becomes far more serious in cloud, at night or when another instrument shares the failed power source.
| Conditions | Practical response |
|---|---|
| Day VMC | Remain oriented by outside references, use the magnetic compass for heading checks, avoid entering IMC and land at a suitable aerodrome if the indication cannot be restored. |
| Night VMC | Use a disciplined instrument cross-check because the external horizon may be weak or absent. Favour a nearby suitable airport with good weather and lighting. |
| IMC or IFR | Fly partial panel, advise ATC of the unreliable heading indication and request simpler routing or no-gyro vectors if needed. Declare urgency or an emergency if aircraft control, navigation or terrain clearance is threatened. |
No-gyro vectors replace assigned headings with instructions to start and stop turns. They reduce dependence on the failed indicator, but the pilot still has to control bank and turn rate using reliable instruments.
The nearest runway is not always the most suitable diversion. Consider weather, terrain, remaining fuel, runway facilities, maintenance support and whether reaching it requires more time in IMC.
Can you keep using the autopilot?
Disconnect the autopilot and flight director when they may be following the same suspect heading source, unless the aircraft manual confirms that the selected mode remains valid.
Changing from heading mode to navigation mode does not necessarily isolate the fault. An integrated autopilot may still use the failed AHRS for attitude, bank or heading data. Unexpected turns, persistent bank commands or disagreement with the standby compass are reasons to disconnect immediately and hand-fly.
How can you fly without a heading indicator?
Use the magnetic compass for direction and reliable attitude or turn instruments to control the aircraft, making small corrections and allowing the indications to settle.
- For straight flight: establish wings level with a reliable attitude indicator, turn coordinator or outside horizon, then read the compass after the aircraft stabilises.
- For turns: use a known turn rate and time the manoeuvre. At a standard rate of 3 degrees per second, a 90-degree turn takes about 30 seconds, but use the aircraft's approved technique and instrument markings.
- For compass roll-out: allow for magnetic turning error, which changes with heading, latitude and hemisphere. Do not apply a northern-hemisphere mnemonic blindly when flying elsewhere.
- For navigation: VOR, NDB or approved area-navigation course guidance can reduce reliance on raw heading. Our explanation of using radio-navigation guidance as a directional cross-check covers the underlying technique.
A GPS ground track is useful supporting information, but it is not the aircraft's heading. Wind can create a substantial difference between the direction the nose points and the path over the ground.
Practising the failure in a flight simulator
Practise conventional gyro, vacuum-system and glass-cockpit failures separately because they remove different combinations of information. Begin from a stable attitude, disable the autopilot, identify the failed source by cross-checking, and then fly compass headings, timed turns and a diversion without restoring the instrument.
Failure modelling varies between simulators and aircraft add-ons, particularly for electrical buses, dual AHRS installations and standby instruments. Use the model's documented systems rather than assuming every cockpit behaves like a basic trainer; our structured partial-panel preparation guidance explains how to turn this exercise into useful instrument practice.