Narrative:

IFR x-county for part 141 commercial pilot syllabus, returning to offutt for a full stop. I was the cfii, my student was flying the aircraft and talking on the radio. We were given vectors for a right downwind to ILS runway 30 at offutt. We were cruising at 7000' and oma approach cleared us to 6000' at pilot's discretion; we opted to stay at 7000'. Later we were cleared to maintain 5000', and in the descent cleared to 4000'. While descending down to 4000', my student (I believe) acknowledged a clearance to descend to 3000', which was assigned to another aircraft. The controller heard our readback and did not correct us. Descending through 3300' now, the controller requested us to say our altitude and we responded with 3000'. The controller informed us that we were assigned 4000' and to climb immediatley, and we did. About 400' in the climb, the controller called traffic at 10 O'clock on final at 3000' for an approach to runway 32L at eppley; we called traffic in sight. The controller cleared us back down to 3000' and advised us to maintain visibility sep. Throughout the descent from 7000' the controller gave us numerous heading changes. Apparently he was laterally trying to space us in between the final approach course for runway 30 at offutt and runway 32L at omaha (eppley). There were at least 2 aircraft, one on each of the 2 final approachs, and I saw a third being turned to base leg for runway 30 at offutt. Everybody was being assigned 3000', which is the standard vectoring altitude here. I had all of the traffic in sight. In summary, I feel that there was confusion between us and the controller that neither party felt at the time existed because readbacks were occurring. Checks and balances, standard procedures, etc, lead us to think that 3000' was our assigned altitude, when the controller had other ideas. Instead of threading us through the needle between 2 approach courses, a vector over offutt for a left downwind may have been more prudent and less confusing. Supplemental information from acn 141620: nearing 4000' I became unsure of the altitude to which we were cleared, so I asked my instrument if we were cleared to 3000'. He confirmed we were, so I continued to descend to 3000'. It is possible that we were not cleared to 3000', although my instrument and I thought we were. I had only 4 hours of actual or simulated INS flight since my INS chkride on 4/X/89, and 1.5 hours of those were on the day of the incident. I was very rusty and somewhat saturated. I was unsure of the altitude to which I was cleared and, although my instrument confirmed 3000', I should have queried approach control.

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Original NASA ASRS Text

Title: IFR SMA DESCENDED BELOW ASSIGNED ALT AND CONFLICTED WITH ANOTHER IFR ACFT.

Narrative: IFR X-COUNTY FOR PART 141 COMMERCIAL PLT SYLLABUS, RETURNING TO OFFUTT FOR A FULL STOP. I WAS THE CFII, MY STUDENT WAS FLYING THE ACFT AND TALKING ON THE RADIO. WE WERE GIVEN VECTORS FOR A RIGHT DOWNWIND TO ILS RWY 30 AT OFFUTT. WE WERE CRUISING AT 7000' AND OMA APCH CLRED US TO 6000' AT PLT'S DISCRETION; WE OPTED TO STAY AT 7000'. LATER WE WERE CLRED TO MAINTAIN 5000', AND IN THE DSNT CLRED TO 4000'. WHILE DSNDING DOWN TO 4000', MY STUDENT (I BELIEVE) ACKNOWLEDGED A CLRNC TO DSND TO 3000', WHICH WAS ASSIGNED TO ANOTHER ACFT. THE CTLR HEARD OUR READBACK AND DID NOT CORRECT US. DSNDING THROUGH 3300' NOW, THE CTLR REQUESTED US TO SAY OUR ALT AND WE RESPONDED WITH 3000'. THE CTLR INFORMED US THAT WE WERE ASSIGNED 4000' AND TO CLB IMMEDIATLEY, AND WE DID. ABOUT 400' IN THE CLB, THE CTLR CALLED TFC AT 10 O'CLOCK ON FINAL AT 3000' FOR AN APCH TO RWY 32L AT EPPLEY; WE CALLED TFC IN SIGHT. THE CTLR CLRED US BACK DOWN TO 3000' AND ADVISED US TO MAINTAIN VIS SEP. THROUGHOUT THE DSNT FROM 7000' THE CTLR GAVE US NUMEROUS HDG CHANGES. APPARENTLY HE WAS LATERALLY TRYING TO SPACE US IN BTWN THE FINAL APCH COURSE FOR RWY 30 AT OFFUTT AND RWY 32L AT OMAHA (EPPLEY). THERE WERE AT LEAST 2 ACFT, ONE ON EACH OF THE 2 FINAL APCHS, AND I SAW A THIRD BEING TURNED TO BASE LEG FOR RWY 30 AT OFFUTT. EVERYBODY WAS BEING ASSIGNED 3000', WHICH IS THE STANDARD VECTORING ALT HERE. I HAD ALL OF THE TFC IN SIGHT. IN SUMMARY, I FEEL THAT THERE WAS CONFUSION BTWN US AND THE CTLR THAT NEITHER PARTY FELT AT THE TIME EXISTED BECAUSE READBACKS WERE OCCURRING. CHKS AND BALS, STANDARD PROCS, ETC, LEAD US TO THINK THAT 3000' WAS OUR ASSIGNED ALT, WHEN THE CTLR HAD OTHER IDEAS. INSTEAD OF THREADING US THROUGH THE NEEDLE BTWN 2 APCH COURSES, A VECTOR OVER OFFUTT FOR A LEFT DOWNWIND MAY HAVE BEEN MORE PRUDENT AND LESS CONFUSING. SUPPLEMENTAL INFO FROM ACN 141620: NEARING 4000' I BECAME UNSURE OF THE ALT TO WHICH WE WERE CLRED, SO I ASKED MY INSTR IF WE WERE CLRED TO 3000'. HE CONFIRMED WE WERE, SO I CONTINUED TO DSND TO 3000'. IT IS POSSIBLE THAT WE WERE NOT CLRED TO 3000', ALTHOUGH MY INSTR AND I THOUGHT WE WERE. I HAD ONLY 4 HRS OF ACTUAL OR SIMULATED INS FLT SINCE MY INS CHKRIDE ON 4/X/89, AND 1.5 HRS OF THOSE WERE ON THE DAY OF THE INCIDENT. I WAS VERY RUSTY AND SOMEWHAT SATURATED. I WAS UNSURE OF THE ALT TO WHICH I WAS CLRED AND, ALTHOUGH MY INSTR CONFIRMED 3000', I SHOULD HAVE QUERIED APCH CTL.

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.