Narrative:

On dec/xx/91 I was PIC and PF of an mdt on a scheduled flight from dutch harbor to anchorage international. We had been vectored onto the localizer and given approach clearance for the ILS runway 6R. While descending through 1900 MSL to our initial approach altitude of 1600 MSL, we got a 'terrain' warning on the ground proximity warning system. At that point I advanced the power levers and initiated a climb. Simultaneously anchorage approach advised that we were at an unsafe altitude for our sector and check altimeter 28.98. The first officer responded that the altimeter was already at 29.98. The controller then said 'no sir I said 28.98.' by the time this exchange took place I had reset my altimeter from 29.98 to 28.98 and was back on the correct altitude (1600 MSL). The first officer then reset his altimeter to the correct setting of 28.98. (He also had 29.98 in his side.) with our altimeters reset and crosschecked and our altitude confirmed by approach control, we continued the approach and landed without incident. It is my opinion that the primary cause of this incident was the fact that the altimeter setting was copied down incorrectly (as 29.98 rather than 28.98) by the first officer and this error was not noticed by me. A contributing factor was that the first officer and I were particularly busy on the radio. There were several times that we were using both radios simultaneously. This was because we needed constant updates on alternate airport WX and flight planning information on the company frequency. We were keeping a close watch on this because dutch harbor to anchorage is a maximum range trip for the aircraft and we were experiencing unforecast low WX throughout the anchorage bowl. In addition, I am a high 'mins' captain (less than 100 hours PIC in type) and anchorage WX 1000 RVR less than my min of 4500 RVR for the hour before our ETA. This made for a very busy pre descent and descent phase and I was unable to supervise the first officer's duties as closely as I would like. The first officer is just as new to the type as I am. Normal procedure at my airline is to reset altimeters to field pressure through 18000 MSL on descent and check them again on the 'descent and approach check.' all checklists and procedures were followed in a normal manner. Simply put, the main cause of this incident was error on the part of both crew members. One way which ATC could have helped might have been to point out that our radio transmissions, i.e., 'flight number is out of 7500 for 5000, etc' were 1000 ft low from the time we were below 18000. This was not noticed. I can't remember if the word 'low' was used to precede the altimeter of 28.98 by ATC or on the ATIS. I feel that this could have been prevented by a more thorough xchking between my first officer and I. I usually always listen ATIS myself even while acting as the PF. On this day I didn't listen to the entire ATIS (#2 communication) because of workload on the other radio (#1 communication). This is a perfect example of how each crew member needs to take care of his individual side of the aircraft then xchk each other for accuracy, rather than one pilot simply matching the information that the other one has.

Google
 

Original NASA ASRS Text

Title: ACR MDT ALTDEV OVERSHOT DURING DSCNT FOR IAP ILS APCH TO ANC. ACFT WAS BELOW CLRNC ALT OUTSIDE FAF ACTIVATING GND PROX WARNING SYS AND MIN SAFE ALT WARNING.

Narrative: ON DEC/XX/91 I WAS PIC AND PF OF AN MDT ON A SCHEDULED FLT FROM DUTCH HARBOR TO ANCHORAGE INTL. WE HAD BEEN VECTORED ONTO THE LOC AND GIVEN APCH CLRNC FOR THE ILS RWY 6R. WHILE DSNDING THROUGH 1900 MSL TO OUR INITIAL APCH ALT OF 1600 MSL, WE GOT A 'TERRAIN' WARNING ON THE GND PROX WARNING SYS. AT THAT POINT I ADVANCED THE PWR LEVERS AND INITIATED A CLB. SIMULTANEOUSLY ANCHORAGE APCH ADVISED THAT WE WERE AT AN UNSAFE ALT FOR OUR SECTOR AND CHK ALTIMETER 28.98. THE FO RESPONDED THAT THE ALTIMETER WAS ALREADY AT 29.98. THE CTLR THEN SAID 'NO SIR I SAID 28.98.' BY THE TIME THIS EXCHANGE TOOK PLACE I HAD RESET MY ALTIMETER FROM 29.98 TO 28.98 AND WAS BACK ON THE CORRECT ALT (1600 MSL). THE FO THEN RESET HIS ALTIMETER TO THE CORRECT SETTING OF 28.98. (HE ALSO HAD 29.98 IN HIS SIDE.) WITH OUR ALTIMETERS RESET AND XCHKED AND OUR ALT CONFIRMED BY APCH CTL, WE CONTINUED THE APCH AND LANDED WITHOUT INCIDENT. IT IS MY OPINION THAT THE PRIMARY CAUSE OF THIS INCIDENT WAS THE FACT THAT THE ALTIMETER SETTING WAS COPIED DOWN INCORRECTLY (AS 29.98 RATHER THAN 28.98) BY THE FO AND THIS ERROR WAS NOT NOTICED BY ME. A CONTRIBUTING FACTOR WAS THAT THE FO AND I WERE PARTICULARLY BUSY ON THE RADIO. THERE WERE SEVERAL TIMES THAT WE WERE USING BOTH RADIOS SIMULTANEOUSLY. THIS WAS BECAUSE WE NEEDED CONSTANT UPDATES ON ALTERNATE ARPT WX AND FLT PLANNING INFO ON THE COMPANY FREQ. WE WERE KEEPING A CLOSE WATCH ON THIS BECAUSE DUTCH HARBOR TO ANCHORAGE IS A MAX RANGE TRIP FOR THE ACFT AND WE WERE EXPERIENCING UNFORECAST LOW WX THROUGHOUT THE ANCHORAGE BOWL. IN ADDITION, I AM A HIGH 'MINS' CAPT (LESS THAN 100 HRS PIC IN TYPE) AND ANCHORAGE WX 1000 RVR LESS THAN MY MIN OF 4500 RVR FOR THE HR BEFORE OUR ETA. THIS MADE FOR A VERY BUSY PRE DSCNT AND DSCNT PHASE AND I WAS UNABLE TO SUPERVISE THE FO'S DUTIES AS CLOSELY AS I WOULD LIKE. THE FO IS JUST AS NEW TO THE TYPE AS I AM. NORMAL PROC AT MY AIRLINE IS TO RESET ALTIMETERS TO FIELD PRESSURE THROUGH 18000 MSL ON DSCNT AND CHK THEM AGAIN ON THE 'DSCNT AND APCH CHK.' ALL CHKLISTS AND PROCS WERE FOLLOWED IN A NORMAL MANNER. SIMPLY PUT, THE MAIN CAUSE OF THIS INCIDENT WAS ERROR ON THE PART OF BOTH CREW MEMBERS. ONE WAY WHICH ATC COULD HAVE HELPED MIGHT HAVE BEEN TO POINT OUT THAT OUR RADIO TRANSMISSIONS, I.E., 'FLT NUMBER IS OUT OF 7500 FOR 5000, ETC' WERE 1000 FT LOW FROM THE TIME WE WERE BELOW 18000. THIS WAS NOT NOTICED. I CAN'T REMEMBER IF THE WORD 'LOW' WAS USED TO PRECEDE THE ALTIMETER OF 28.98 BY ATC OR ON THE ATIS. I FEEL THAT THIS COULD HAVE BEEN PREVENTED BY A MORE THOROUGH XCHKING BTWN MY FO AND I. I USUALLY ALWAYS LISTEN ATIS MYSELF EVEN WHILE ACTING AS THE PF. ON THIS DAY I DIDN'T LISTEN TO THE ENTIRE ATIS (#2 COM) BECAUSE OF WORKLOAD ON THE OTHER RADIO (#1 COM). THIS IS A PERFECT EXAMPLE OF HOW EACH CREW MEMBER NEEDS TO TAKE CARE OF HIS INDIVIDUAL SIDE OF THE ACFT THEN XCHK EACH OTHER FOR ACCURACY, RATHER THAN ONE PLT SIMPLY MATCHING THE INFO THAT THE OTHER ONE HAS.

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.