Narrative:

Flight plan shv-afw. Arriving in fort worth area, during descent, altimeters were set to local afw ATIS report at 29.95. During descent, ATC did not give a local altimeter setting until clearance altitude deviation noticed. Last assigned altitude was 3400 ft. ATC notified us mode C indicted 3000 ft, 'altimeter dfw 29.55, maintain 3000 ft.' ATC did not give altimeter setting when altitude assignment below flight levels. Supplemental information from acn 504332: I recorded the afw airport ATIS about 100 NM out. The transmission was fast and had some static. At first, the altimeter setting was not clear. So I listened to the broadcast 3 times and thought the setting was 29.95. It was actually 29.55. I prepared the landing data card (with the incorrect altimeter setting) and passed it to the pilots. At transition altitude, the pilots set their altimeters to 29.95. When the low altitude sector controller was contacted he did not give us the local altimeter setting. We were assigned a minimum altitude of 3400 ft MSL. After a couple of mins at this altitude, the controller gave us the correct local altimeter setting and informed us we were 300 ft below our minimum altitude. The correct setting of 29.55, once reset, gave us an indicated altitude of 3100 ft. No further discussion of the error. We had no traffic or terrain conflicts and were at the incorrect altitude for only a min or two. I think if ATC had given us the local setting when we transitioned through FL180, we may have avoided this error.

Google
 

Original NASA ASRS Text

Title: A B727 CARGO FLT FLIES 400 FT UNDER HIS MINIMUM ALT ASSIGNMENT WITH THE WRONG ALTIMETER SETTING 15 MI NW OF DFW, TX.

Narrative: FLT PLAN SHV-AFW. ARRIVING IN FORT WORTH AREA, DURING DSCNT, ALTIMETERS WERE SET TO LCL AFW ATIS RPT AT 29.95. DURING DSCNT, ATC DID NOT GIVE A LCL ALTIMETER SETTING UNTIL CLRNC ALTDEV NOTICED. LAST ASSIGNED ALT WAS 3400 FT. ATC NOTIFIED US MODE C INDICTED 3000 FT, 'ALTIMETER DFW 29.55, MAINTAIN 3000 FT.' ATC DID NOT GIVE ALTIMETER SETTING WHEN ALT ASSIGNMENT BELOW FLT LEVELS. SUPPLEMENTAL INFO FROM ACN 504332: I RECORDED THE AFW ARPT ATIS ABOUT 100 NM OUT. THE XMISSION WAS FAST AND HAD SOME STATIC. AT FIRST, THE ALTIMETER SETTING WAS NOT CLR. SO I LISTENED TO THE BROADCAST 3 TIMES AND THOUGHT THE SETTING WAS 29.95. IT WAS ACTUALLY 29.55. I PREPARED THE LNDG DATA CARD (WITH THE INCORRECT ALTIMETER SETTING) AND PASSED IT TO THE PLTS. AT TRANSITION ALT, THE PLTS SET THEIR ALTIMETERS TO 29.95. WHEN THE LOW ALT SECTOR CTLR WAS CONTACTED HE DID NOT GIVE US THE LCL ALTIMETER SETTING. WE WERE ASSIGNED A MINIMUM ALT OF 3400 FT MSL. AFTER A COUPLE OF MINS AT THIS ALT, THE CTLR GAVE US THE CORRECT LCL ALTIMETER SETTING AND INFORMED US WE WERE 300 FT BELOW OUR MINIMUM ALT. THE CORRECT SETTING OF 29.55, ONCE RESET, GAVE US AN INDICATED ALT OF 3100 FT. NO FURTHER DISCUSSION OF THE ERROR. WE HAD NO TFC OR TERRAIN CONFLICTS AND WERE AT THE INCORRECT ALT FOR ONLY A MIN OR TWO. I THINK IF ATC HAD GIVEN US THE LCL SETTING WHEN WE TRANSITIONED THROUGH FL180, WE MAY HAVE AVOIDED THIS ERROR.

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.