An Instructor pilot took evasive action from a Bonanza whose pilot was making intermittent traffic calls as both aircraft were doing practice approaches at CGZ.

Narrative

While practicing instrument approaches at Casa Grande (CGZ) airport; my students and I were operating under the guidelines set forth by the Arizona Flight Training Workgroup regarding making frequent position reports; requesting the 'Top of Stack' at the Stanfield (TFD) VORTAC; and entering the approach in the prescribed manner. Unfortunately; there was a Bonanza operating in the area. The pilot in command of this aircraft was apparently unaware of the recommended procedures; or didn't care. His radio calls were infrequent; and usually after he heard someone else was already in the location where he was heading. As my student and I approached TFD; I called and determined that there was no aircraft at the VOR; and entered the procedure turn hold at 3;500 FT. The pilot of the Bonanza called that he was on a one mile final for the GPS approach to Runway 23 at CGZ. (This was the only call this pilot made on the entire approach). My student began the procedure turn inbound for the ILS Runway 5 approach into CGZ; and I reported that we were; 'Procedure turn inbound at Stanfield VOR at 3;500 FT.' Just as we approached the VOR; I was about to report that we were 'VOR Inbound' on the approach; the same Bonanza passed overhead approximately 100 FT higher than us. At no point did this pilot make any radio call that he was approaching the TFD VOR; let alone request traffic information. Upon spotting the Bonanza; I took immediate control of the aircraft; and pushed into a sharp dive for about 300 FT. In an admittedly unprofessional move; I screamed over the radio that we 'were over the TFD VOR at 3;500 FT and that 'someone' just passed over us at the same altitude.' Again; there was no call from this Bonanza until two minutes later when he reported that he was 'procedure turn inbound for the ILS approach.' In the future; if I detect a pilot who seems determine to not follow the outlined procedures in this area; I will declare the airspace unsafe and vector my students to another aerodrome for exercises. I did file a company safety report on this event. Unfortunately; the pilot of the Bonanza in question never used his full call sign. During the infrequent calls that he did make; he simply referred to himself as 'Bonanza-XX.'