Aircraft limited to < 85 deg North

[Grum]

My aircraft is limited to operations between North / South 85 degrees, and I would like to know why we can not navigate over the poles. In reality we have no need to do so but I'd like to know the reason.

We have 3 IRS using ring lasor gyros, 2 GPS and FMS using all resources including DME/DME etc

At N75deg the system automatically changes to TRUE north to cope with rapid variation changes.

So why can I not fly over the pole?

Thanks

[FlyingStone]

Perhaps it has do to something with FMS software not being able (or not allowed, since the airline didn't pay enough) to perform calculations near the poles. I don't think the normal FMS can fly something like this.

[FlightPathOBN]

http://www.pprune.org/tech-log/38960...-latitude.html

[Microburst2002]

Do any airlinera use grid north as a reference for polar navigation?

I mean, true jeading are useless too in the poles. Or they just keep the magenta line with whatever heading is displayed in the ND?

[FlightPathOBN]

I have done a few RNP procedures that use grid north, DeadHorse, AK is one that comes to mind.

[Spooky 2]

The 777 and the 787 both have a Grid Navigation option. Maybe the 747 also, but I'm not sure. I know that Korean Air has developed some modest procedures for this. Not sure who else is using it.

[BUGS/BEARINGS/BOXES]

Diversions are hard to come by. Iqualuit, Thule, erm............. Somewhere with a log fire? And lots of logs! Some aircraft are prohibited to enter the compass unreliable and unusable areas due to certification/ flight testing.

[Grum]

Thanks FlightpathOBN for the link. That seems to explain.

[Dan Winterland]

It disturbs the polar bears.

[compressor stall]

Do any airliners use grid north as a reference for polar navigation?

This should answer your question. The pic has appeared a couple of times before on here. There are also enough clues on the screen to work out where in the world it is to the nearest tens of miles. The bright sparks who have previously answered this are to remain silent.