First officer of a widebody transport air carrier aircraft inadvertently set millibars instead of in...

Attributes
ACN	253204
Time
Date	199310
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ham
State Reference	FO
Altitude	msl bound lower : 2500 msl bound upper : 3000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	enroute airway : ham
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 160 flight time total : 6000 flight time type : 160
ASRS Report	253204
Person 2
Affiliation	company : air carrier
Function	other personnel other
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 160 flight time total : 10000 flight time type : 160
ASRS Report	253129
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : became reoriented other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Received ATIS about 200 mi out and it was coming in kind of broken. Mistook 991 millibars for 2991 inches for the altimeter setting. So when approach control also said 991 for the altimeter setting we were locked into thinking 2991 inches (a common altimeter setting in united states). We were cleared to descend to 3000 ft and we descended to 2500 ft and then immediately pulled back up to 3000 ft as we noticed our mistake. We were in no conflict with other aircraft and we were 2500 ft above the ground. It would be helpful if international controllers or ATIS would give altimeter settings in both millibars and inches to foreign aircraft! Supplemental information from acn 253129: crew consisted of a brand new captain on first trip, a copilot who hadn't flown in 5 weeks, and myself as relief pilot. I usually fly with very experienced crew members and did not adequately back up my fellow pilots. Approach control questioned our altitude. We immediately discovered our mistake and returned to the correct altitude. This episode was caused by fatigue, inexperience, and unwarranted assumptions. The problem was able to develop, I feel, because of no standardized way of reporting altimeter settings in europe. Some airports report only millibars and some (to be helpful) report both millibars and inches of mercury. Then, some report qnh, abc, xyz and whatever else they can come up with. We were led down the primrose path by our own shortcomings, but it can and will happen to other crews operating in this theater of operations.

Original NASA ASRS Text

Title: FO OF A WDB ACR ACFT INADVERTENTLY SET MILLIBARS INSTEAD OF INCHES IN THE ALTIMETER RESULTING IN OVERSHOOTING DSCNT ALT.

Narrative: RECEIVED ATIS ABOUT 200 MI OUT AND IT WAS COMING IN KIND OF BROKEN. MISTOOK 991 MILLIBARS FOR 2991 INCHES FOR THE ALTIMETER SETTING. SO WHEN APCH CTL ALSO SAID 991 FOR THE ALTIMETER SETTING WE WERE LOCKED INTO THINKING 2991 INCHES (A COMMON ALTIMETER SETTING IN UNITED STATES). WE WERE CLRED TO DSND TO 3000 FT AND WE DSNDED TO 2500 FT AND THEN IMMEDIATELY PULLED BACK UP TO 3000 FT AS WE NOTICED OUR MISTAKE. WE WERE IN NO CONFLICT WITH OTHER ACFT AND WE WERE 2500 FT ABOVE THE GND. IT WOULD BE HELPFUL IF INTL CTLRS OR ATIS WOULD GIVE ALTIMETER SETTINGS IN BOTH MILLIBARS AND INCHES TO FOREIGN ACFT! SUPPLEMENTAL INFORMATION FROM ACN 253129: CREW CONSISTED OF A BRAND NEW CAPT ON FIRST TRIP, A COPLT WHO HADN'T FLOWN IN 5 WKS, AND MYSELF AS RELIEF PLT. I USUALLY FLY WITH VERY EXPERIENCED CREW MEMBERS AND DID NOT ADEQUATELY BACK UP MY FELLOW PLTS. APCH CTL QUESTIONED OUR ALT. WE IMMEDIATELY DISCOVERED OUR MISTAKE AND RETURNED TO THE CORRECT ALT. THIS EPISODE WAS CAUSED BY FATIGUE, INEXPERIENCE, AND UNWARRANTED ASSUMPTIONS. THE PROB WAS ABLE TO DEVELOP, I FEEL, BECAUSE OF NO STANDARDIZED WAY OF RPTING ALTIMETER SETTINGS IN EUROPE. SOME ARPTS RPT ONLY MILLIBARS AND SOME (TO BE HELPFUL) RPT BOTH MILLIBARS AND INCHES OF MERCURY. THEN, SOME RPT QNH, ABC, XYZ AND WHATEVER ELSE THEY CAN COME UP WITH. WE WERE LED DOWN THE PRIMROSE PATH BY OUR OWN SHORTCOMINGS, BUT IT CAN AND WILL HAPPEN TO OTHER CREWS OPERATING IN THIS THEATER OF OPS.

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.

First officer of a widebody transport air carrier aircraft inadvertently set millibars instead of inches in the altimeter resulting in overshooting descent altitude.