Narrative:

On dec/xx/94, I was the PNF on airlines flight xx. We were shooting the ILS runway 3 into hobbs municipal airport, hobbs, NM. The captain was flying through the approach, past the OM and before the decision ht he was at full scale deflection on the localizer and the GS. We went through the standard go around and missed approach procedure. The missed approach was to climb to 5000 ft then a climbing left turn to the VOR and out the 243 degree radial to prett intersection and hold. We had briefed the approach and the missed procedure prior to going missed approach. While in the left hand turn back to the VOR, we broke out of the clouds on top. The first thing I saw was the cessna 208 a few mi to my right. As a courtesy to ATC I reported the traffic in sight as I checked in from the tower frequency. ATC replied and told us to maintain 5000 ft. At this time we were climbing through 5600 ft. The captain heard the call and we started down. ATC asked me to say my altitude. I called out approaching 6000 ft after looking at my altimeter which works off a separate system then the captain's altimeter. We continued to the VOR and soon picked up the IFR clearance to abq. We fly the rest of the day without any knowledge that there was a problem. After the same shift the next day, approximately 30 hours later, we heard that we had been in violation. After hearing of the report on us I came to realize that the mode C on that aircraft had given abq controllers a few false readings, but that was on a common call until I found out later that, that could be 1 possible problem. I believe that we could have slowed down on the approach and used a little foresight. The entire flight has made me more conscientious about my flying today: supplemental information from acn 292519: I told him to report our altitude, and he called us at 6000 ft. I look at his altimeter it was at 5900 ft mine was at 5800 ft. I started an immediate descent, we never reached 6000 ft on either altimeter. We were told to maintain 5000 ft and the other aircraft was told to maintain 7000 ft.

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Original NASA ASRS Text

Title: ALT BUST.

Narrative: ON DEC/XX/94, I WAS THE PNF ON AIRLINES FLT XX. WE WERE SHOOTING THE ILS RWY 3 INTO HOBBS MUNICIPAL ARPT, HOBBS, NM. THE CAPT WAS FLYING THROUGH THE APCH, PAST THE OM AND BEFORE THE DECISION HT HE WAS AT FULL SCALE DEFLECTION ON THE LOC AND THE GS. WE WENT THROUGH THE STANDARD GAR AND MISSED APCH PROC. THE MISSED APCH WAS TO CLB TO 5000 FT THEN A CLBING L TURN TO THE VOR AND OUT THE 243 DEG RADIAL TO PRETT INTXN AND HOLD. WE HAD BRIEFED THE APCH AND THE MISSED PROC PRIOR TO GOING MISSED APCH. WHILE IN THE L HAND TURN BACK TO THE VOR, WE BROKE OUT OF THE CLOUDS ON TOP. THE FIRST THING I SAW WAS THE CESSNA 208 A FEW MI TO MY R. AS A COURTESY TO ATC I RPTED THE TFC IN SIGHT AS I CHKED IN FROM THE TWR FREQ. ATC REPLIED AND TOLD US TO MAINTAIN 5000 FT. AT THIS TIME WE WERE CLBING THROUGH 5600 FT. THE CAPT HEARD THE CALL AND WE STARTED DOWN. ATC ASKED ME TO SAY MY ALT. I CALLED OUT APCHING 6000 FT AFTER LOOKING AT MY ALTIMETER WHICH WORKS OFF A SEPARATE SYS THEN THE CAPT'S ALTIMETER. WE CONTINUED TO THE VOR AND SOON PICKED UP THE IFR CLRNC TO ABQ. WE FLY THE REST OF THE DAY WITHOUT ANY KNOWLEDGE THAT THERE WAS A PROB. AFTER THE SAME SHIFT THE NEXT DAY, APPROX 30 HRS LATER, WE HEARD THAT WE HAD BEEN IN VIOLATION. AFTER HEARING OF THE RPT ON US I CAME TO REALIZE THAT THE MODE C ON THAT ACFT HAD GIVEN ABQ CTLRS A FEW FALSE READINGS, BUT THAT WAS ON A COMMON CALL UNTIL I FOUND OUT LATER THAT, THAT COULD BE 1 POSSIBLE PROB. I BELIEVE THAT WE COULD HAVE SLOWED DOWN ON THE APCH AND USED A LITTLE FORESIGHT. THE ENTIRE FLT HAS MADE ME MORE CONSCIENTIOUS ABOUT MY FLYING TODAY: SUPPLEMENTAL INFO FROM ACN 292519: I TOLD HIM TO RPT OUR ALT, AND HE CALLED US AT 6000 FT. I LOOK AT HIS ALTIMETER IT WAS AT 5900 FT MINE WAS AT 5800 FT. I STARTED AN IMMEDIATE DSCNT, WE NEVER REACHED 6000 FT ON EITHER ALTIMETER. WE WERE TOLD TO MAINTAIN 5000 FT AND THE OTHER ACFT WAS TOLD TO MAINTAIN 7000 FT.

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.