Altitude deviation caused by a very low altimeter setting.

Attributes
ACN	299990
Time
Date	199503
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	msl bound lower : 16000 msl bound upper : 17000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau tower : bjc
Operator	common carrier : air carrier
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	enroute airway : zau
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : private pilot : commercial pilot : flight engineer pilot : instrument pilot : atp
Experience	flight time last 90 days : 180 flight time total : 5500 flight time type : 390
ASRS Report	299990
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 150 flight time total : 19000 flight time type : 1900
ASRS Report	299626
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : became reoriented
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation
Situations
ATC Facility	procedure or policy : unspecified

Narrative:

Cleared to descend to 17000 ft MSL. I was busy flying the airplane and missed the radio call from center giving the altimeter setting. I asked the captain for the setting. I heard 'xx.38.' unsure of what the first 2 numbers were, I just assumed 30.38 and put that setting in the altimeter. The captain also put a setting in his altimeter, ie, I saw him move his hand toward the altimeter. Neither of us made a '1000 ft above' callout. At about 17500 ft on my altimeter, I announced 'leveling at 17000 ft.' the captain said 'we're leveling at 16000 ft, get back up to altitude.' I climbed to correct altitude. No traffic on TCASII or observed. No conflict resulted. Center made no comment about the incident. The fault was mine for not setting and verifying the correct altimeter, for assuming 29.38 as being unreasonably low altimeter setting and jumping on 30.38. I went through the motions of the descent checklist without calling for it, and the captain was too busy with radio calls and ATIS to xchk my setting. He missed the '1000 ft above' call which would have been correct on his altimeter. I did not xchk his altimeter at any time -- merely noted his setting something by moving his hand and assumed we had the same number set. I now do a descent checklist before 18000 ft MSL and pay more attention to the xchk. Callback conversation with reporter revealed the following information: the reporter flies the B-767-300 for a major united states air carrier. At the time of the incident, 'we weren't paying attention to each other.' at no time did the center say anything like 'altimeter setting 29.38 low.' apparently this is standard procedure in alaska and canada where there are more wild swings in altimeter settings. The first officer 'just jumped at conclusions' at a more normal setting of 30.38. ARTCC did not seem to notice the transgression as nothing was said. The first officer immediately climbed when his captain noticed the error.

Original NASA ASRS Text

Title: ALTDEV CAUSED BY A VERY LOW ALTIMETER SETTING.

Narrative: CLRED TO DSND TO 17000 FT MSL. I WAS BUSY FLYING THE AIRPLANE AND MISSED THE RADIO CALL FROM CTR GIVING THE ALTIMETER SETTING. I ASKED THE CAPT FOR THE SETTING. I HEARD 'XX.38.' UNSURE OF WHAT THE FIRST 2 NUMBERS WERE, I JUST ASSUMED 30.38 AND PUT THAT SETTING IN THE ALTIMETER. THE CAPT ALSO PUT A SETTING IN HIS ALTIMETER, IE, I SAW HIM MOVE HIS HAND TOWARD THE ALTIMETER. NEITHER OF US MADE A '1000 FT ABOVE' CALLOUT. AT ABOUT 17500 FT ON MY ALTIMETER, I ANNOUNCED 'LEVELING AT 17000 FT.' THE CAPT SAID 'WE'RE LEVELING AT 16000 FT, GET BACK UP TO ALT.' I CLBED TO CORRECT ALT. NO TFC ON TCASII OR OBSERVED. NO CONFLICT RESULTED. CTR MADE NO COMMENT ABOUT THE INCIDENT. THE FAULT WAS MINE FOR NOT SETTING AND VERIFYING THE CORRECT ALTIMETER, FOR ASSUMING 29.38 AS BEING UNREASONABLY LOW ALTIMETER SETTING AND JUMPING ON 30.38. I WENT THROUGH THE MOTIONS OF THE DSCNT CHKLIST WITHOUT CALLING FOR IT, AND THE CAPT WAS TOO BUSY WITH RADIO CALLS AND ATIS TO XCHK MY SETTING. HE MISSED THE '1000 FT ABOVE' CALL WHICH WOULD HAVE BEEN CORRECT ON HIS ALTIMETER. I DID NOT XCHK HIS ALTIMETER AT ANY TIME -- MERELY NOTED HIS SETTING SOMETHING BY MOVING HIS HAND AND ASSUMED WE HAD THE SAME NUMBER SET. I NOW DO A DSCNT CHKLIST BEFORE 18000 FT MSL AND PAY MORE ATTN TO THE XCHK. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES THE B-767-300 FOR A MAJOR UNITED STATES ACR. AT THE TIME OF THE INCIDENT, 'WE WEREN'T PAYING ATTN TO EACH OTHER.' AT NO TIME DID THE CTR SAY ANYTHING LIKE 'ALTIMETER SETTING 29.38 LOW.' APPARENTLY THIS IS STANDARD PROC IN ALASKA AND CANADA WHERE THERE ARE MORE WILD SWINGS IN ALTIMETER SETTINGS. THE FO 'JUST JUMPED AT CONCLUSIONS' AT A MORE NORMAL SETTING OF 30.38. ARTCC DID NOT SEEM TO NOTICE THE TRANSGRESSION AS NOTHING WAS SAID. THE FO IMMEDIATELY CLBED WHEN HIS CAPT NOTICED THE 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.