MD80 flight crew discovered altitude deviation was the result of a wrong altimeter setting.

Attributes
ACN	497257
Time
Date	200101
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : dtw.airport
State Reference	MI
Altitude	msl bound lower : 11000 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : d21.tracon
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : spica.spica2
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp pilot : instrument
Experience	flight time last 90 days : 210 flight time total : 9100 flight time type : 2800
ASRS Report	497257
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : published procedure
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to assigned altitude
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

After leveling off at 12000 ft for spica intersection (spica 2 arrival dtw), the first officer noticed an altitude deviation. He verified it with ATIS and the altimeter was 29.56 instead of 30.56 which put me 1000 ft low. It was immediately corrected and ATC (dtw approach) said nothing. After landing, I contacted detroit approach and they showed nothing on their system as a deviation. I also contacted cleveland approach who handed us off prior to dtw and they showed no deviation.

Original NASA ASRS Text

Title: MD80 FLC DISCOVERED ALTDEV WAS THE RESULT OF A WRONG ALTIMETER SETTING.

Narrative: AFTER LEVELING OFF AT 12000 FT FOR SPICA INTXN (SPICA 2 ARR DTW), THE FO NOTICED AN ALTDEV. HE VERIFIED IT WITH ATIS AND THE ALTIMETER WAS 29.56 INSTEAD OF 30.56 WHICH PUT ME 1000 FT LOW. IT WAS IMMEDIATELY CORRECTED AND ATC (DTW APCH) SAID NOTHING. AFTER LNDG, I CONTACTED DETROIT APCH AND THEY SHOWED NOTHING ON THEIR SYS AS A DEV. I ALSO CONTACTED CLEVELAND APCH WHO HANDED US OFF PRIOR TO DTW AND THEY SHOWED NO DEV.

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.