I was flying over the north pole tonight, and received a message in the FMC I have never seen before. "Split IRS Operations". Does anyone know what this means and what I need to do about it?

Here's an excerpt from an old B747 operations manual:FMC Polar OperationsPolar operation begins when the FMC calculated airplane position passes north of84°N or south of 84°S. FMCs revert to split IRS operation, the CDU messageSPLIT IRS OPERATION displays, and each FMC connects to a different IRU.Radio update corrections are lost and FMCs incrementally remove the differencebetween FMC and IRU positions.Split IRS operation may result in differences between Captain’s and F/O’s NDs ifGPS updating is not available.When GPS is available, GPS updating continues until the FMC position passesnorth of 88.5°N or south of 88.5°S. At this point, GPS update corrections are lostand the FMC position becomes a single IRU position. When the FMC positionpasses south of 88.5°N or north of 88.5°S, GPS updating resumes.When both FMC positions pass south of 83.5°N or north of 83.5°S latitude, FMCsreturn to normal operation using the triple mixed IRU position.Hope this helps as I have no expertise.Dugald Walker

Here's an excerpt from an old B747 operations manual:FMC Polar OperationsPolar operation begins when the FMC calculated airplane position passes north of84°N or south of 84°S. FMCs revert to split IRS operation, the CDU messageSPLIT IRS OPERATION displays, and each FMC connects to a different IRU.Radio update corrections are lost and FMCs incrementally remove the differencebetween FMC and IRU positions.Split IRS operation may result in differences between Captain’s and F/O’s NDs ifGPS updating is not available.When GPS is available, GPS updating continues until the FMC position passesnorth of 88.5°N or south of 88.5°S. At this point, GPS update corrections are lostand the FMC position becomes a single IRU position. When the FMC positionpasses south of 88.5°N or north of 88.5°S, GPS updating resumes.When both FMC positions pass south of 83.5°N or north of 83.5°S latitude, FMCsreturn to normal operation using the triple mixed IRU position.Hope this helps as I have no expertise.Dugald Walker

Yeah it does thanks....I read through the manual, and didn't find this aparently. Thanks for this

This is the Boeing manual, not the PMDG manual. It's on page 11.31.7 of my version. I just searched for "split irs".Dugald Walker.