First try it with the joins un-nested. Note, you will no longer be able to use the View Designer to modify this view. You will have to maintain all the code for this in a PRG.[e.g., Create SQL View MyView as...]:

SELECT operation.CODE, operation.description, cRpt011.*, cRpt012.*,;
	cRpt013.*, cRpt014.*;
	FROM  operation ;
                    LEFT OUTER JOIN cRpt011;
                             ON  operation.CODE = cRpt011.operation1;
                    LEFT OUTER JOIN cRpt012;
	               ON  operation.CODE = cRpt012.operation2 ;
	      LEFT OUTER JOIN cRpt013;
	               ON  operation.CODE = cRpt013.operation3 ;
	      LEFT OUTER JOIN cRpt014 ;
	               ON  operation.CODE = cRpt014.operation4 ;
	ORDER BY 1;
	INTO CURSOR cLast