Narrative:

While on an IFR cross country flight for training purposes; the aircraft was flown below the MVA for that area. The student pilot was flying at the time of the event. We were told to descend from 6000 ft to what the student and instructor heard as 3000 ft and fly a 150 degree heading for vectors to an ILS approach to pou. The descent was started and the assigned heading flown. Approximately 5-6 mins later the controller instructed us to climb back to 4000 ft and told us that we were below the MVA. He also asked us if we had visual contact with the ground. We informed him that we were VMC and had visual contact with the surface. At that time; I looked at the altimeter and saw that we had descended to 3400 ft MSL which appeared to be at least 2000-2500 ft AGL. I then told the controller that we were instructed to descend to 3000 ft; not 4000 ft. I never got a reply from the controller regarding my query. I then asked my student what altitude he had heard and he said he heard 3000 ft as well. The controller was very busy with other traffic so I did not question further and he made no further comments to us. The remainder of the flight went without incident. It is very possible that both myself and my student misunderstood our assigned altitude but I am confident we read back 'descend to 3000 ft' to the controller. Since we were not corrected at that time both the controller and ourselves could have missed the error. The controller was working extremely hard and was dealing with many VFR and IFR aircraft as well as a radar problem earlier in the morning from what I picked up so I do not know if he may have misspoke in his instructions. Even though the airplane may have been below the MVA; at no point in time were we too close to the ground or obstructions and visual contact was never lost. However; I feel that future diligence to make sure altitudes and assignments are clear to both pilots and controllers can eliminate confusion and possible problems.

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Original NASA ASRS Text

Title: A C172 INSTRUCTOR AND HIS STUDENT HEARD AND READ BACK AN ATC ASSIGNED ALT OF 3000 FT WHICH WAS BELOW MVA. ATC REASSIGNED A HIGHER ALT.

Narrative: WHILE ON AN IFR XCOUNTRY FLT FOR TRAINING PURPOSES; THE ACFT WAS FLOWN BELOW THE MVA FOR THAT AREA. THE STUDENT PLT WAS FLYING AT THE TIME OF THE EVENT. WE WERE TOLD TO DSND FROM 6000 FT TO WHAT THE STUDENT AND INSTRUCTOR HEARD AS 3000 FT AND FLY A 150 DEG HDG FOR VECTORS TO AN ILS APCH TO POU. THE DSCNT WAS STARTED AND THE ASSIGNED HDG FLOWN. APPROX 5-6 MINS LATER THE CTLR INSTRUCTED US TO CLB BACK TO 4000 FT AND TOLD US THAT WE WERE BELOW THE MVA. HE ALSO ASKED US IF WE HAD VISUAL CONTACT WITH THE GND. WE INFORMED HIM THAT WE WERE VMC AND HAD VISUAL CONTACT WITH THE SURFACE. AT THAT TIME; I LOOKED AT THE ALTIMETER AND SAW THAT WE HAD DSNDED TO 3400 FT MSL WHICH APPEARED TO BE AT LEAST 2000-2500 FT AGL. I THEN TOLD THE CTLR THAT WE WERE INSTRUCTED TO DSND TO 3000 FT; NOT 4000 FT. I NEVER GOT A REPLY FROM THE CTLR REGARDING MY QUERY. I THEN ASKED MY STUDENT WHAT ALT HE HAD HEARD AND HE SAID HE HEARD 3000 FT AS WELL. THE CTLR WAS VERY BUSY WITH OTHER TFC SO I DID NOT QUESTION FURTHER AND HE MADE NO FURTHER COMMENTS TO US. THE REMAINDER OF THE FLT WENT WITHOUT INCIDENT. IT IS VERY POSSIBLE THAT BOTH MYSELF AND MY STUDENT MISUNDERSTOOD OUR ASSIGNED ALT BUT I AM CONFIDENT WE READ BACK 'DSND TO 3000 FT' TO THE CTLR. SINCE WE WERE NOT CORRECTED AT THAT TIME BOTH THE CTLR AND OURSELVES COULD HAVE MISSED THE ERROR. THE CTLR WAS WORKING EXTREMELY HARD AND WAS DEALING WITH MANY VFR AND IFR ACFT AS WELL AS A RADAR PROB EARLIER IN THE MORNING FROM WHAT I PICKED UP SO I DO NOT KNOW IF HE MAY HAVE MISSPOKE IN HIS INSTRUCTIONS. EVEN THOUGH THE AIRPLANE MAY HAVE BEEN BELOW THE MVA; AT NO POINT IN TIME WERE WE TOO CLOSE TO THE GND OR OBSTRUCTIONS AND VISUAL CONTACT WAS NEVER LOST. HOWEVER; I FEEL THAT FUTURE DILIGENCE TO MAKE SURE ALTS AND ASSIGNMENTS ARE CLR TO BOTH PLTS AND CTLRS CAN ELIMINATE CONFUSION AND POSSIBLE PROBS.

Data retrieved from NASA's ASRS site as of January 2009 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.