If you create two calculation fields that parse out the number and text portions you need for sorting you can get the sort order you want by sorting on those two calculation fields.
Let's assume your call signs are entered into a text field named CallSign. Define the first field, cSort1, as simply CallSign but set its return value to number--not text. Sorting on this field will sort them by the number portion of the call sign.
Define a second field, cSort2, to parse out only the text to the right of the last numerical digit in the call sign:
RightWords ( Substitute(CallSign ; [0 ; " "] ; [1 ; " "] ; [2 ; " "] ; [3 ; " "] ; [4 ; " "] ; [5 ; " "] ; [6 ; " "] ; [7 ; " "] ; [8 ; " "] ; [9 ; " "] ) ; 1 )
Now, if you specify cSort1, then cSort2 in your sort order, you should get the order you've specified.
Thank you very much!