UTM Confusion during Campaign

Last night, I played Mission 6-1-0 in the Georgian Cross and there were 2 JTAC's as well as a Predator UAV giving me targets.

Everything was going ok until JTAC started giving me 5 digit coordinates, which threw up an error on the CDU.

I have read about this problem, so I tried entering the coordinates with a 0 in front, then again in position 4 but this provided me with targets marked on the HUD as up to 400nm away.

I checked the area in my reference card (below) and in Google Earth, using the first two letters and numbers, KN79, and the target wasn't 400nm away but it was still more than 100nm from my current position.

After JTAC 1 was killed, JTAC 2 and the UAV controller continued to provide me with targets over 400nm away six times.

If JTAC gives me the coordinates KN82264, what do I have to enter as a UTM waypoint - KN082264 OR KN822064?

Because I tried both of these and the HUD showed roughly 400nm to target both times.

I have read several posts on here about this problem but I don't understand if I am the problem, JTAC doesn't like me or if it's a bug.

Thanks for your help.

Are you on the same grid? either 37T or 38T? Look on your map (your attached thumbnail) and along the G and K grid lines they are not square, that is because they are in different grid references. More than likely your target is in the other grid to the one you are in, and you need to tell the CDU this. This has been mentioned in other threads, try reading through this one

http://forums.eagle.ru/showthread.php?t=69021

Andy, you're right. I was in GG but I don't understand how I am supposed to enter to tell the CDU I'm on the other grid? I only have the coordinates JTAC gives me.

I've read through the document you linked but I still don't get it.

What am I missing?

also mentioned here, the entry on page 3 has a thumbnail that shows it pretty well.

http://forums.eagle.ru/showthread.php?t=76127&highlight=38T&page=2

I should have said "Spheroids" above.

In a nutshell, you take off in say grid GG which is in Spheroid 37T, JTAC gives you a target in grid KN which is in Spheroid 38T. Because you set off in 37T, that is where your CDU thinks all your coordinates are for, you give it the UTM but only put in XXNNNNNN, missing off the initial 38T, so your CDU points to that spot in Spheroid 37T. It mentions in the last link above how to put the right Spheroid into the CDU.

Thanks Andy, that last link cleared it up for me.

I should have said "Spheroids" above.

You should have said 'grid zone'. ;)

37T and 38T = grid zones.

GG, KN etc = grid squares.

First character of the grid square designator should be all you need to determine if it is 37T or 38T. Before H in the alphabet - it's 37T. After H - it's 38T.