F-14B proper INS alignment procedure?

Hi folks,

In the 2018 dev update, https://forums.eagle.ru/showthread.php?t=206097 HB speaks of:

An INS device must be prepared before it is ready for navigation. This process is called alignment. Before the alignment begins, the RIO has to input aircraft coordinates and altitude.

In the RIO checklist, from the HB F-14 manual pages;

Step 5: NAV MODE switch - Align.

Step 14: CAP - Enter own aircraft latitude, longitude and field or ship elevation.

Which way is the proper way? Enter lat/long of own aircraft first, then switching to NAV Align GND or setting the switch first and then entering own aircraft position?

Or does it matter at all? Meaning the INS will take any data it is fed either before or after the nav mode switch has been set to align?

Recently, I have had two flights where I had a severely degraded INS system where the groundspeed would be in excess of 3600 knots and we ended up over greenland, 15000Nm away from Kutaisi airport. I know this since I had HomeBase waypoint hooked before it left the 400Nm range of the TID. We didn't do any hard manoevring, in fact, the INS was 9 miles off when we had to begin our taxi to the active, having spend 20 minutes on the ground and the alignment process ended with a nice diamond. I verified entered lat/long, elevation and magnetic variation and they did check out.

TACAN updates did somewhat alliviate the problem but in the end it really didn't matter that much when all the datalink targets went outside of 400Nm.

We're trying to see if I did something wrong or if there are netsync issues at hand or maybe version incompatibility between pilot and rio.

I'd like to know what the proper routine is to align the INS. I've had flights where it didn't act up as weird as it did the last time so there's something out there.

When setting the switch to ALIGN you have about 1-2 minutes to enter the respective data (lat/long + altitude in case of GND ALIGN). In those 2 minutes some basic gyro alignment happens that does not require said data. You can of course always enter the data before starting the alignment.

When setting the switch to ALIGN you have about 1-2 minutes to enter the respective data (lat/long + altitude in case of GND ALIGN). In those 2 minutes some basic gyro alignment happens that does not require said data. You can of course always enter the data before starting the alignment.

Right, the Alignment of your Gyros is independent of the co-ordinates you enter. The alignment is the calibration of your Aircraft to accurately sense forces applied to the A/C and those translate into changes in co-ordinates through the Gyros, Accelerometers and an integral computer. Think of the co-ordinates you enter in terms of a CNC machine. They are so it can display your positions in your work space, so you know where you are, which is also why you can apply the inflight visual or tacan fix. Therefor it doesn't matter when you enter it during the process or even what order.

If your system had been degraded, likely the Gyros/Accelerometers have been damaged (yes in this case its simulated before someone feels the need to point that out.) and no longer able to accurately sense forces and/or integrate those into accurate delta distances / co-ordinate changes, regardless of how you entered your starting co-ordinates or even the fixes you applied.

As to how it got damaged is a good question. I think you are on the right path with a desync between the pilot and RIO?

well, we tested it a bit more and eventually it came down to operator error. Instead of entering magvar 6.2 degrees, I edited own aircraft heading to 62 degrees.

I'll make a separate post about this because I am curious about the observed behavior.