B737 descends below cleared altitude when flight crew misset altimeters.

Attributes
ACN	622234
Time
Date	200304
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : den.airport
State Reference	CO
Altitude	msl bound lower : 10500 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : d01.tracon
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : commercial pilot : instrument
Experience	flight time last 90 days : 50 flight time total : 6500 flight time type : 150
ASRS Report	622234
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued advisory flight crew : overcame equipment problem flight crew : became reoriented flight crew : returned to assigned altitude
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While descending to 11000 ft, ATC advised us that we were going below 11000 ft. Both pilots crosschecked and realized that their altimeter settings did not agree. Copilot had 29.58 inches and captain had 39.58 inches. We were at 10560 ft on the copilot's altimeter. The captain quickly disconnected the autoplt, climbed back to 11000 ft and reset his altimeter. Captain called approach control on the ground and was advised by the supervisor that no paperwork would be filed.

Original NASA ASRS Text

Title: B737 DSNDS BELOW CLRED ALT WHEN FLT CREW MISSET ALTIMETERS.

Narrative: WHILE DSNDING TO 11000 FT, ATC ADVISED US THAT WE WERE GOING BELOW 11000 FT. BOTH PLTS XCHKED AND REALIZED THAT THEIR ALTIMETER SETTINGS DID NOT AGREE. COPLT HAD 29.58 INCHES AND CAPT HAD 39.58 INCHES. WE WERE AT 10560 FT ON THE COPLT'S ALTIMETER. THE CAPT QUICKLY DISCONNECTED THE AUTOPLT, CLBED BACK TO 11000 FT AND RESET HIS ALTIMETER. CAPT CALLED APCH CTL ON THE GND AND WAS ADVISED BY THE SUPVR THAT NO PAPERWORK WOULD BE FILED.

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.