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.