Altitude deviation descent through assigned altitude.

Attributes
ACN	315720
Time
Date	199509
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : oxi
State Reference	IN
Altitude	msl bound lower : 15500 msl bound upper : 16000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 240 flight time total : 16000 flight time type : 8000
ASRS Report	315720
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : became reoriented
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Captain disconnected autoplt when it failed to capture 16000 ft and altitude alerter came on. He returned aircraft to 16000 ft. ZAU said there was 'no problem' when asked if there was a problem with our altitude deviation. ZAU cleared us immediately to descend to 11000 ft. There was no traffic conflict. On subsequent dscnts into O'hare, autoplt also failed to capture altitude and descended through altitude alerter altitude. We were ready for situation in ATC approach area and didn't bust the 200 ft buffer on altitude. At 1000 FPM rate of descent, there was less altitude deviation than we were told the first time by ZAU to use a good rate of descent, and to increase airspeed to 320 KTS. First officer was out of loop getting ATIS when ZAU told captain to descend to 16000 ft. First officer came back in loop when altitude alerter went off. First officer heard ZAU say there was 'no problem' with altitude and heard center tell us to continue descent to 11000 ft. When at O'hare, captain made autoplt write-up in logbook. Autoplt was put on MEL at chicago and released for flight.

Original NASA ASRS Text

Title: ALTDEV DSCNT THROUGH ASSIGNED ALT.

Narrative: CAPT DISCONNECTED AUTOPLT WHEN IT FAILED TO CAPTURE 16000 FT AND ALT ALERTER CAME ON. HE RETURNED ACFT TO 16000 FT. ZAU SAID THERE WAS 'NO PROB' WHEN ASKED IF THERE WAS A PROB WITH OUR ALTDEV. ZAU CLRED US IMMEDIATELY TO DSND TO 11000 FT. THERE WAS NO TFC CONFLICT. ON SUBSEQUENT DSCNTS INTO O'HARE, AUTOPLT ALSO FAILED TO CAPTURE ALT AND DSNDED THROUGH ALT ALERTER ALT. WE WERE READY FOR SIT IN ATC APCH AREA AND DIDN'T BUST THE 200 FT BUFFER ON ALT. AT 1000 FPM RATE OF DSCNT, THERE WAS LESS ALTDEV THAN WE WERE TOLD THE FIRST TIME BY ZAU TO USE A GOOD RATE OF DSCNT, AND TO INCREASE AIRSPD TO 320 KTS. FO WAS OUT OF LOOP GETTING ATIS WHEN ZAU TOLD CAPT TO DSND TO 16000 FT. FO CAME BACK IN LOOP WHEN ALT ALERTER WENT OFF. FO HEARD ZAU SAY THERE WAS 'NO PROB' WITH ALT AND HEARD CTR TELL US TO CONTINUE DSCNT TO 11000 FT. WHEN AT O'HARE, CAPT MADE AUTOPLT WRITE-UP IN LOGBOOK. AUTOPLT WAS PUT ON MEL AT CHICAGO AND RELEASED FOR FLT.

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.