From a technical standpoint, the main thing that differentiates the $2449 G5 heading indicator
from the $2195 G5 attitude indicator is a remote heading sensor.
If you were lucky--or wealthy--enough to have an RMI (remote magnetic indicator), which was really nothing more than that bearing pointer on a compass card that, instead of merely being fixed or manually adjustable, was slaved to your heading indicator
, life got a whole lot easier.
The D1's heading indicator
rotates in arc format and a magenta turn rate arc projects in the direction of the turn.
These include the artificial horizon/attitude indicator and the heading indicator
or directional gyro.
While I've had only one AHRS failure, I've lost three conventional attitude indicators and one vacuum pump that took both the AI and heading indicator
Finally, the HSI compass card can be slaved to a magnetic sensor or non-slaved like your basic heading indicator
Fail the heading indicator
and it just locks in place.
Halfway through an IFR cross country flight, it appears your instrument panel has suffered a couple deaths in the family: the attitude indicator, and the heading indicator
Better master that HSI; it's rapidly replacing the lowly heading indicator
For legal IFR, the panel would need an attitude indicator, heading indicator
, turn coordinator or turn-and-bank indicator, sideslip indicator and clock to meet the minimum equipment requirements for IFR flight.
On a vacuum pump, round-gauge airplane, you'll need to bring the power up to get minimum suction so the heading indicator
gyro is up to speed.
This can be caused by late recognition of heading changes, tension on the controls, misinterpretation of the heading indicator
(and correcting in the wrong direction), failure to appreciate changing effectiveness of rudder control as the aircraft accelerates and other factors.