HSI drift around the boat.

[RodWan Olds]

I've noticed that when you are spending a lot of time around the boat the 25-30deg drift can make running the CASE 1-3 downwind confusing sometimes. Switching compass mode to COMP seems to alleviate this and allows running the radial and reciprocal again without the need for head math.

Is this the intended behavior? Or should the INS slave mode switch automatically when an excessive drift is detected. Obviously this only matters when doing multiple traps in a row, but still it would be nice to confirm what actual pilots did on qual nights, and how it's suppose to work when inside the CVN bubble.  

[The_Tau]

4 hours ago, RodWan Olds said:

I've noticed that when you are spending a lot of time around the boat the 25-30deg drift can make running the CASE 1-3 downwind confusing sometimes. Switching compass mode to COMP seems to alleviate this and allows running the radial and reciprocal again without the need for head math.

Is this the intended behavior? Or should the INS slave mode switch automatically when an excessive drift is detected. Obviously this only matters when doing multiple traps in a row, but still it would be nice to confirm what actual pilots did on qual nights, and how it's suppose to work when inside the CVN bubble.  

As I recall CV is 100k ton of metal which has effect on magnetic compasses. If I understand correctly, using Comp should give you bad reading because of that. The CG - gyro should work independently from that if you aligned gyros properly before hand. Please correct me if I am wrong  

Edited July 3, 2022 by The_Tau

[Northstar98]

As The_Tau said, I wouldn't be surprised if Heatblur has modelled magnetic deviation (note, not variation or declination - which is the difference between true and magnetic north), where the magnetic compass gets influenced by local magnetic fields (such as an aircraft carrier).

Edited July 4, 2022 by Northstar98

[Karon]

@The_Tau and @Northstar98 have already answered, so I'll add just a quick note.

16 hours ago, RodWan Olds said:

Or should the INS slave mode switch automatically when an excessive drift is detected.

Check your TID, when discrepancies greater than (IIRC) 5° are detected, the VM acronym appears, and it alternates with the current nav mode. At this point, the crew can switch to a mode that bypasses the vC, thus offsetting the problem, at least partially.
 

On a general note, be careful when INS and related devices start acting funny because, although you can bypass or fix most of the issues, not all your displays are fed by the same systems. Namely, the BDHI is fed directly by the AHRS, whereas the info for other displays are provided by another piece of avionics (CSDC perhaps, I need to check). Therefore, depending on what you do, you may still have deviated indications here or there.

[draconus]

2 hours ago, Northstar98 said:

...I wouldn't be surprised if Heatblur has modelled magnetic deviation (note, not variation or declination), where the magnetic compass gets influenced by local magnetic fields (such as an aircraft carrier).

It is modeled.

http://www.heatblur.se/F-14Manual/general.html#carrier-alignment

Quote

Note that you will get erroneous heading readings on a carrier, even if fine align is complete. The heading can deviate up to 20 or 30 degrees, depending on the parking position on the carrier and the carrier’s heading, due to the carrier’s own magnetic field and induced magnetic field. It is important that the flight crew know the carrier’s BRC. The magnetic variation caused by the carrier’s magnetic distortion will go away shortly after take off. This magnetic distortion does not impact the alignment quality.