A CL65 crew, on descent into cvg, overshot a STAR crossing restr.

Attributes
ACN	534814
Time
Date	200201
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : charz
State Reference	OH
Altitude	msl bound lower : 7200 msl bound upper : 8000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid.artcc tracon : cvg.tracon
Operator	common carrier : air carrier
Make Model Name	Regional Jet CL65, Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival star : cince.cince4
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : cfi pilot : private pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 200 flight time total : 2500 flight time type : 900
ASRS Report	534814
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : overshoot non adherence : clearance non adherence : far non adherence : published procedure
Independent Detector	atc equipment other atc equipment : radar other controllera other flight crewa
Resolutory Action	flight crew : returned to assigned altitude
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Environmental Factor Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were descending on the cince four arrival into cvg. Descending through FL180 we set the altimeters to 29.72, the local altimeter setting given to us by the center controller. We performed the descent checklist and the captain verbally confirmed the altimeter setting per the checklist. We were then cleared to descend to 8000 ft. I was setting up for the approach and looked up at the instruments and noticed my altimeter was showing us descending through 7300 ft. I immediately called out we were assigned 8000 ft to the captain, and noticed his altimeter read 8300 ft. We determined his altimeter had changed to 30.72, reset it to the correct setting of 29.72 and began a climb back to 8000 ft. As we were leveling at 8000 ft center asked us about our altitude. We confirmed we were low and correcting. There were no traffic conflicts during the altitude deviation. The incorrect altimeter setting caused a 1000 ft difference between the 2 altimeters. I do not know how or why the altimeter setting changed. The only way I can think of to avoid this situation in the future is to have an altimeter setting comparator to warn of a difference between 2 altimeters.

Original NASA ASRS Text

Title: A CL65 CREW, ON DSCNT INTO CVG, OVERSHOT A STAR XING RESTR.

Narrative: WE WERE DSNDING ON THE CINCE FOUR ARR INTO CVG. DSNDING THROUGH FL180 WE SET THE ALTIMETERS TO 29.72, THE LCL ALTIMETER SETTING GIVEN TO US BY THE CTR CTLR. WE PERFORMED THE DSCNT CHKLIST AND THE CAPT VERBALLY CONFIRMED THE ALTIMETER SETTING PER THE CHKLIST. WE WERE THEN CLRED TO DSND TO 8000 FT. I WAS SETTING UP FOR THE APCH AND LOOKED UP AT THE INSTS AND NOTICED MY ALTIMETER WAS SHOWING US DSNDING THROUGH 7300 FT. I IMMEDIATELY CALLED OUT WE WERE ASSIGNED 8000 FT TO THE CAPT, AND NOTICED HIS ALTIMETER READ 8300 FT. WE DETERMINED HIS ALTIMETER HAD CHANGED TO 30.72, RESET IT TO THE CORRECT SETTING OF 29.72 AND BEGAN A CLB BACK TO 8000 FT. AS WE WERE LEVELING AT 8000 FT CTR ASKED US ABOUT OUR ALT. WE CONFIRMED WE WERE LOW AND CORRECTING. THERE WERE NO TFC CONFLICTS DURING THE ALTDEV. THE INCORRECT ALTIMETER SETTING CAUSED A 1000 FT DIFFERENCE BTWN THE 2 ALTIMETERS. I DO NOT KNOW HOW OR WHY THE ALTIMETER SETTING CHANGED. THE ONLY WAY I CAN THINK OF TO AVOID THIS SIT IN THE FUTURE IS TO HAVE AN ALTIMETER SETTING COMPARATOR TO WARN OF A DIFFERENCE BTWN 2 ALTIMETERS.

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.