Changing grid for UTM coords

[Topgun505]

So, contacted a JTAC for a mission, got the UTM coords and plugged them into the CDU.  No problem.  Flipped over to mission and cycled to the inputted target point and .... it's several hundred miles away.  Upon examination of the F10 map I believe it is because the JTAC was in one of the large grids on the map 38T (on Caucus map) , and evidently when you plug in UTM coords the A-10C CDU automatically puts the grid part in for you based on what grid you are currently in ... so if you happen to not be in the same grid (so, for example, if you are in 37T while the JTAC is in 38T) then you just plugged in the coordinates ... for the wrong grid.  The problem, however, is from looking at the CDU that line of the coords is in format of 37T XXXXX (I forget exactly how many characters was after the grid, but it wasn't just simply 37T or 38T, etc.  So what exact syntax is it looking for on that line of the CDU?  And if it really is more than just 37T, how do you determine the the rest of that line?  

[Yurgon]

Well spotted.  

 

The grid zone designator goes on its own line. Just punch in "37T" and hit the LSK above the one where you normally input in the rest of the grid.

 

The base-grid is always the one for the waypoint that's currently selected in the CDU (on the waypoint page; I'm NOT referring to the steerpoint here), so if you add new waypoints, you don't have to update the grid every single time, as long as the GZD remains the same.

 

Likewise, the two-letter designation doesn't actually need to be entered if it remains the same. So if the currently selected waypoint in the CDU waypoint page is at, say, "KM 568 145" and you want to update it to "KM 600 509", you can just enter "600509" and it'll put it into (aka retain) KM automatically.

[Topgun505]

Hmm.  When I ran into that situation I tried to do just that (just put in 37T and input it on that line), but it kicked back a CDU error.  I'll have to try that again.