Narrative:

Problem arose when on an IFR cross country training flight from osh (oshkosh) to cwa (mosinee/central wi) to grb (green bay) and return to osh. A clearance was received. Prior to arrival of the ste (stevens point) VOR on victor 63, it went something like this: small aircraft aircraft, cleared to the danci OM (on the ILS runway 8 approach at mosinee/central wi) via the 17 DME arc transition off the auw VOR, maintain 4000. We passed the ste VOR and proceeded directly toward the auw VOR to intercept the 17 DME arc. After we were established on the arc, I mistakenly told my student that we were allowed to be at 3000 ft, the published arc altitude. After continuing on the arc for a while, the student started a descent from 4000 to 3000. I then started to wonder if the ATC controller wanted us at 3000 or not, so I was going to ask over the radio. The ATC controller was busy talking to other aircraft at the time so by the time I was able to communicate, we had already lost 600 ft. I told him that we were descending from 4000 to 3000 and that we were established on the arc. He then said that I was supposed to maintain 4000 and that I should climb back up. So we did. As we were climbing, his radar contact was lost, because their radar cannot reach that area. We lost a total of 700 ft before we commenced our climb back up. The rest of the approach and trip went fine. The event that went wrong is that we descended 700 ft before we were supposed to, being misled by what was printed on the approach plate and the clearance given by the center controller. To me it is misleading hearing the words 'cleared to danci intersection via the 17 DME arc transition,' and seeing a published min altitude on the arc transition. This gives you the idea that once you are on a published segment of an approach with a min altitude specified, that you are allowed to be at that published altitude.

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Original NASA ASRS Text

Title: FLT INSTRUCTOR ON IFR XCOUNTRY DSNDED BELOW ASSIGNED ALT DURING A DME APCH TRANSITION ARC.

Narrative: PROBLEM AROSE WHEN ON AN IFR XCOUNTRY TRAINING FLT FROM OSH (OSHKOSH) TO CWA (MOSINEE/CENTRAL WI) TO GRB (GREEN BAY) AND RETURN TO OSH. A CLRNC WAS RECEIVED. PRIOR TO ARR OF THE STE (STEVENS POINT) VOR ON VICTOR 63, IT WENT SOMETHING LIKE THIS: SMA ACFT, CLRED TO THE DANCI OM (ON THE ILS RWY 8 APCH AT MOSINEE/CENTRAL WI) VIA THE 17 DME ARC TRANSITION OFF THE AUW VOR, MAINTAIN 4000. WE PASSED THE STE VOR AND PROCEEDED DIRECTLY TOWARD THE AUW VOR TO INTERCEPT THE 17 DME ARC. AFTER WE WERE ESTABLISHED ON THE ARC, I MISTAKENLY TOLD MY STUDENT THAT WE WERE ALLOWED TO BE AT 3000 FT, THE PUBLISHED ARC ALT. AFTER CONTINUING ON THE ARC FOR A WHILE, THE STUDENT STARTED A DSCNT FROM 4000 TO 3000. I THEN STARTED TO WONDER IF THE ATC CTLR WANTED US AT 3000 OR NOT, SO I WAS GOING TO ASK OVER THE RADIO. THE ATC CTLR WAS BUSY TALKING TO OTHER ACFT AT THE TIME SO BY THE TIME I WAS ABLE TO COMMUNICATE, WE HAD ALREADY LOST 600 FT. I TOLD HIM THAT WE WERE DSNDING FROM 4000 TO 3000 AND THAT WE WERE ESTABLISHED ON THE ARC. HE THEN SAID THAT I WAS SUPPOSED TO MAINTAIN 4000 AND THAT I SHOULD CLB BACK UP. SO WE DID. AS WE WERE CLBING, HIS RADAR CONTACT WAS LOST, BECAUSE THEIR RADAR CANNOT REACH THAT AREA. WE LOST A TOTAL OF 700 FT BEFORE WE COMMENCED OUR CLB BACK UP. THE REST OF THE APCH AND TRIP WENT FINE. THE EVENT THAT WENT WRONG IS THAT WE DSNDED 700 FT BEFORE WE WERE SUPPOSED TO, BEING MISLED BY WHAT WAS PRINTED ON THE APCH PLATE AND THE CLRNC GIVEN BY THE CTR CTLR. TO ME IT IS MISLEADING HEARING THE WORDS 'CLRED TO DANCI INTXN VIA THE 17 DME ARC TRANSITION,' AND SEEING A PUBLISHED MIN ALT ON THE ARC TRANSITION. THIS GIVES YOU THE IDEA THAT ONCE YOU ARE ON A PUBLISHED SEGMENT OF AN APCH WITH A MIN ALT SPECIFIED, THAT YOU ARE ALLOWED TO BE AT THAT PUBLISHED ALT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.