Air carrier crew misset altimeter by 1000' during period low extremely low barometric pressure.

Attributes
ACN	160762
Time
Date	199010
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : anc
State Reference	AK
Altitude	msl bound lower : 9000 msl bound upper : 10000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : anc
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 5500 flight time type : 800
ASRS Report	160762
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were issued a clearance to descend maintain FL100 (10000') altimeter 28.85. No special emphasis in the extremely low altimeter. The first officer erroneously read back 'cleared to 10000' 29.85.' no challenge to the readback was received. ATIS at anchorage was off the air. Upon leveling at 10000', I heard another flight cleared to a lower altitude and issued an altimeter of 28.85. We immediately asked the controller to verify the altimeter and received an acknowledgement that anc altimeter is 28.85. We reset our altimeters and climbed to 10000' as we were 1000' lower from our assigned altitude due to the erroneous altimeter setting. We were at the lower altitude for approximately one min. It is my cockpit procedure to copy the ATIS and compare that with the ATIS that the second officer copies down on the data card as a doublechk of the landing data information. The simultaneous occurrence of an inopertive ATIS, a lock of a challenge to our readback of our descent clearance and no special emphasis on the extremely low altimeter setting by the ATC approach controller, were all contributing factors. There was not any traffic conflict as a result of our descent below our assigned altitude nor any inquiry from ATC as to our altitude.

Original NASA ASRS Text

Title: ACR CREW MISSET ALTIMETER BY 1000' DURING PERIOD LOW EXTREMELY LOW BAROMETRIC PRESSURE.

Narrative: WE WERE ISSUED A CLRNC TO DSND MAINTAIN FL100 (10000') ALTIMETER 28.85. NO SPECIAL EMPHASIS IN THE EXTREMELY LOW ALTIMETER. THE F/O ERRONEOUSLY READ BACK 'CLRED TO 10000' 29.85.' NO CHALLENGE TO THE READBACK WAS RECEIVED. ATIS AT ANCHORAGE WAS OFF THE AIR. UPON LEVELING AT 10000', I HEARD ANOTHER FLT CLRED TO A LOWER ALT AND ISSUED AN ALTIMETER OF 28.85. WE IMMEDIATELY ASKED THE CTLR TO VERIFY THE ALTIMETER AND RECEIVED AN ACKNOWLEDGEMENT THAT ANC ALTIMETER IS 28.85. WE RESET OUR ALTIMETERS AND CLBED TO 10000' AS WE WERE 1000' LOWER FROM OUR ASSIGNED ALT DUE TO THE ERRONEOUS ALTIMETER SETTING. WE WERE AT THE LOWER ALT FOR APPROX ONE MIN. IT IS MY COCKPIT PROC TO COPY THE ATIS AND COMPARE THAT WITH THE ATIS THAT THE S/O COPIES DOWN ON THE DATA CARD AS A DOUBLECHK OF THE LNDG DATA INFO. THE SIMULTANEOUS OCCURRENCE OF AN INOPERTIVE ATIS, A LOCK OF A CHALLENGE TO OUR READBACK OF OUR DSNT CLRNC AND NO SPECIAL EMPHASIS ON THE EXTREMELY LOW ALTIMETER SETTING BY THE ATC APCH CTLR, WERE ALL CONTRIBUTING FACTORS. THERE WAS NOT ANY TFC CONFLICT AS A RESULT OF OUR DSNT BELOW OUR ASSIGNED ALT NOR ANY INQUIRY FROM ATC AS TO OUR ALT.

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.