DC9 altitude deviation dtw.

Attributes
ACN	458780
Time
Date	199912
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : fwa.vortac
State Reference	IN
Altitude	msl bound lower : 11600 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude descent : vacating altitude
Route In Use	arrival star : mizar 3
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 8500 flight time type : 600
ASRS Report	458780
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : multi engine
Events
Anomaly	aircraft equipment problem : critical altitude deviation : overshoot inflight encounter other non adherence : far non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : attitude gyro other flight crewa other flight crewb
Resolutory Action	flight crew : returned to assigned altitude
Consequence	faa : reviewed incident with flight crew other
Supplementary
Problem Areas	Aircraft ATC Human Performance Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

First officer was flying/descending on the mizar 3 arrival into dtw on the autoplt. It appears that the #2 gyro failed and the autoplt failed to level off at 12000 ft MSL as selected. Additionally, the first officer's ADI was giving erroneous bank and descent information. We were busy trying to determine which ADI was incorrect while accelerating to a requested speed of 340 KIAS, which caused us to deviate from altitude by 400 ft.

Original NASA ASRS Text

Title: DC9 ALTDEV DTW.

Narrative: FO WAS FLYING/DSNDING ON THE MIZAR 3 ARR INTO DTW ON THE AUTOPLT. IT APPEARS THAT THE #2 GYRO FAILED AND THE AUTOPLT FAILED TO LEVEL OFF AT 12000 FT MSL AS SELECTED. ADDITIONALLY, THE FO'S ADI WAS GIVING ERRONEOUS BANK AND DSCNT INFO. WE WERE BUSY TRYING TO DETERMINE WHICH ADI WAS INCORRECT WHILE ACCELERATING TO A REQUESTED SPD OF 340 KIAS, WHICH CAUSED US TO DEVIATE FROM ALT BY 400 FT.

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.