Remote Compass readings inaccurate

[bobsk8]

This has happened a few times in the AT6, where the remote compass disagrees with the magnetic compass and heading indicator. I am flying now and the mag compass and heading indicator read 129 and the remote compass reads 45 degrees. I tried resetting the circuit breaker for the remote, and doesn't help. Any ideas. BTW, sometimes it works fine.

[gulredrel]

Normally the magnetic indicator and the remote compass should read the same and you have to adjust the heading indicator (below artificial horizon), as this will change because of gyro drift.
Never had a wrong remote compass reading.

[bobsk8]

Normally the magnetic indicator and the remote compass should read the same and you have to adjust the heading indicator (below artificial horizon), as this will change because of gyro drift.
Never had a wrong remote compass reading.

I have the heading indicator set and once set it stays locked to the magnetic compass. Sometimes the remote compass also gives me the same reading, but on several occasions it is way off, in other words this is an intermittant problem with the remote compass. At one time I worked in an avionics shop in real life, an would suspect a defective sending unit for the remote compass. Maybe I should try tapping on it....

[alan CXA651]

Hi Bobsk8.
Have you compared all 3 to the map , If any was out with an error i would say the stby compass was most liky to be out , but even so , they should all be within a reasonable toleerance of each other , i have just taken my t6 up and mine appear to tally to within a degree or so.
Also i would not expect this as a randam a2a fault , but you never can tell , i assume no hangar faults showing.
regards alan.

[bobsk8]

Hi Bobsk8.
Have you compared all 3 to the map , If any was out with an error i would say the stby compass was most liky to be out , but even so , they should all be within a reasonable toleerance of each other , i have just taken my t6 up and mine appear to tally to within a degree or so.
Also i would not expect this as a randam a2a fault , but you never can tell , i assume no hangar faults showing.
regards alan.

I just found the problem. If I start the T6, and check the remote compass and mag compass after turning on the power, the readings are the same. If I then turn off the power, and tow the aircraft, say 90 degrees to the right, and then reapply power to the aircraft, now the mag compass and remote compass are off by 90 degrees, and will stay that way for the entire flight, until the aircraft is reloaded. This is very easy to duplicate. In order to avoid this, don't tow the aircraft with the power off. Apparently when you load the aircraft into the sim, and then apply power, towing the aircraft, allows the remote compass to keep up with the direction it is pointed. If you cut the power off, then move the aircraft in direction, and power it back up, the remote compass starts up at it's last heading when the aircraft was first loaded into the sim.

[alan CXA651]

Hi Bobsk8.
I have just tried the same thing as you , set it up at KBFI on a stand for small aircraft , all compasses bang on 40 degrees with batt on , i got the same results as you initially , reason i say that , i did not go and fly , but played around with batt on / off untill i moved the aircraft in a position , where all compasses where once again reading 40 degrees , so if you do make the mistake of moveing aircraft with batt off , you can play around untill you get all compasses agreeing once more , its a bit of a fiddle factor , but can be done , maybe you have found a bug.
regards alan.

[mallcott]

Is the flight sim equivalent of hitting it with a hammer not the `D` key, and does that not work to realign?

[alan CXA651]

Hi Mallcott.
Yes it works just tried it.
regards alan.

[bobsk8]

Is the flight sim equivalent of hitting it with a hammer not the `D` key, and does that not work to realign?

I am using P3D and have never seen the D key programmed for anything in the default settings, so maybe that is an FSX default command. Anyway, I just programmed D for "heading reset", and that resets everything to actual aircraft heading.

[bobsk8]

Hi Bobsk8.
I have just tried the same thing as you , set it up at KBFI on a stand for small aircraft , all compasses bang on 40 degrees with batt on , i got the same results as you initially , reason i say that , i did not go and fly , but played around with batt on / off untill i moved the aircraft in a position , where all compasses where once again reading 40 degrees , so if you do make the mistake of moveing aircraft with batt off , you can play around untill you get all compasses agreeing once more , its a bit of a fiddle factor , but can be done , maybe you have found a bug.
regards alan.

From real world experience, I always move the aircraft out of parking space, before firing it up, so that is what caused the problem with the AT6. As long as battery is on and remote compass is active, then it can me towed with no problem. I have now programmed a key for "heading reset" in P3D, and that takes care of the issue.

[mallcott]

There is a widely known `two & four finger shuffle` that experienced simmer use on startup to make sure everything is in sync:

1: Num Lock OFF, hit keypad `5`, Num Lock back ON - this centralises all control surfaces in the sim (and as the real controllers use centralising springs, guarantees matched deflection). Thats three and the fourth is waggle the joystick or yoke slightly (not to the stops) to ensure it is being `read` by the sim, rather than inheriting the `last known` position setting from the previous flight.
This should be done every time the sim is started

2: `D` key by default realigns the compass. You will see A2A aircraft have the bezels slowly rotate. This is instantaneous and can also be used in aircraft that don't have a slaved compass, and to remove compass deviation.

3: The `B` key sets current barometric pressure and will match the sim and aircraft to weather - created or downloaded

It therefore follows that, for the desktop simmer who hasn't messed with the key settings, whenever you press `B`, you press `D` That the `two finger shuffle`.

[bobsk8]

There is a widely known `two & four finger shuffle` that experienced simmer use on startup to make sure everything is in sync:

1: Num Lock OFF, hit keypad `5`, Num Lock back ON - this centralises all control surfaces in the sim (and as the real controllers use centralising springs, guarantees matched deflection). Thats three and the fourth is waggle the joystick or yoke slightly (not to the stops) to ensure it is being `read` by the sim, rather than inheriting the `last known` position setting from the previous flight.
This should be done every time the sim is started

2: `D` key by default realigns the compass. You will see A2A aircraft have the bezels slowly rotate. This is instantaneous and can also be used in aircraft that don't have a slaved compass, and to remove compass deviation.

3: The `B` key sets current barometric pressure and will match the sim and aircraft to weather - created or downloaded

It therefore follows that, for the desktop simmer who hasn't messed with the key settings, whenever you press `B`, you press `D` That the `two finger shuffle`.

I stopped using those shortcut keys many years ago, and like to do everything as I would in the real aircraft. Never had any issue until the remote compass issue, which I believe is a minor bug. I am positive the real aircraft does not behave that way.

[gulredrel]

Can confirm this too. Having power off, the remote compass was a bit off. Switching battery on it aligned itself with the magnetic heading. Switching of power and towing the plane, the remote compass will not align after switching the power back on.

[bobsk8]

Think I found another little bug in this heading issue today. I used the D key to align the remote compass and the heading indicator with the magnetic compass after pushing back. I started a flight and noticed that when I used the autopilot to set the heading, my ATC kept telling me that I was not on the correct heading by 10 degrees or so. Then I noticed that the aircraft was on a heading of say 270, and that is what the mag compass and heading indicator read, but the autopilot heading indicator was telling me I was heading at 258. In other words the autopilot heading and the aircraft heading were now out of sync with each other.
,

[alan CXA651]

Hi Bob.
I dont have auto pilot on this aircraft , i decided it just does not look right in an old aircraft like this so hand flying for me when in this old girl.
Did you bring up the map when this happened , to see the hdg you was on , to varyify which was out.
regards alan.