AN INSTRUCTOR AND HIS STUDENT ENTER THE PATTERN AT A BUSY ARPT IMPROPERLY BECAUSE THE INSTRUCTOR WAS HAVING THE STUDENT TRACK THE LOC FOR THE RECIPROCAL OF THE ACTIVE RWY.

Narrative

MID-AFTERNOON VFR TRAINING FLT; CONDUCTED BY A CFII; WITH A PVT PLT TRANSITIONING FROM A C172 TO A PIPER WARRIOR. WX WAS VFR (CEILING 8000 FT OVCST; VISIBILITY 5 MI IN HAZE). TRAVELING EBOUND TO HOME ARPT; DPA; FROM THE PRACTICE AREA; PLTS RPTED IN; FROM ABOUT 25 NM AWAY; TO DPA CTL TWR AND WERE TOLD TO RPT 'XING THE RIVER FOR L DOWNWIND TO RWY 28.' RWY 28 IS NOT SERVED BY AN INST APCH; BUT ITS RECIPROCAL; RWY 10; HAS A FULL ILS. IN ORDER TO PROVIDE SOME ILS TRACKING EXPERIENCE TO THE PVT PLT; CFII SET UP THE PLT ON THE ILS RWY 10 APCH AFTER ASSESSING; BY MONITORING BOTH DPA TWR AND CHICAGO APCH; THAT NO TFC CONFLICTS EXISTED. PVT PLT FLEW APCH AND; AT PROPER TIME; CFII RPTED TO DPA TWR THAT THE PIPER WAS 'OVER THE RIVER' ('THE RIVER' IS LOCATED ABOUT 4 NM W OF DPA). ABOUT 1 NM AWAY FROM DPA; THE ACFT STARTED A CIRCLING MANEUVER FOR A DOWNWIND ENTRY TO RWY 28. THE DPA TWR REQUESTED THE MANEUVER DUE TO AN ACFT DEPARTING RWY 28. NEITHER CHICAGO APCH NOR THE DPA TWR CLRED THE PIPER FOR THE APCH BECAUSE THE PIPER WAS FLYING UNDER VFR AND NOT UNDER IFR. HOWEVER; IN ACCORDANCE WITH THE 'SEE AND AVOID' TFC AVOIDANCE CONCEPT; THE PIPER MAINTAINING ADEQUATE VIGILANCE FOR POTENTIALLY CONFLICTING TFC; OF WHICH THERE WAS NONE UNTIL THE RWY 28 DEP. LESSONS LEARNED: THE CFII SHOULD HAVE INFORMED THE DPA TWR OF THE PIPER'S INTENTIONS. THE DPA TWR SHOULD HAVE NOTICED; AT AN EARLIER TIME; THE PIPER TRACKING THE LOC BECAUSE THE DPA TWR HAS THE APPROPRIATE RADAR SYS IN PLACE. BOTH OF THESE IMPROVEMENTS WOULD HAVE CONTRIBUTED FURTHER THE SAFETY AROUND DPA.