F28 crew dealing with malfunctioning altitude alerter overshoots assigned altitude on descent.

Attributes
ACN	460953
Time
Date	199912
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zdc.artcc
State Reference	VA
Altitude	msl bound lower : 15600 msl bound upper : 16000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	F28 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 250 flight time total : 10000 flight time type : 900
ASRS Report	460953
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : returned to assigned altitude
Consequence	faa : investigated other other
Supplementary
Problem Areas	Aircraft Company Flight Crew Human Performance
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

We were cleared to 16000 ft. The altitude alert did not go off at 17000 ft. We descended through 16000 ft to approximately 15600 ft when the alerter went off at 15700 ft. We climbed back up to 16000 ft immediately. ZDC asked us to confirm we were at 16000 ft as we were climbing back up through 15750 ft. I told the controller that we were climbing back to 16000 ft and that we were through 15800 ft, which we were at that time. ZDC later (5 mins?) advised us that 'the machine went off on that one' and that it would be looked into. The altitude alert had been erratic all day, but was most erratic on this flight. We had flown the plane for 6 legs and the alerter had gone off at odd altitudes but hadn't missed an altitude yet, ie, it went off at 10000 ft when cleared to 6000 ft and at FL180 when cleared to an altitude lower than 17000 ft, but it had not failed to go off 1000 ft above, before this instance. The TCASII system was not working and MEL'ed.

Original NASA ASRS Text

Title: F28 CREW DEALING WITH MALFUNCTIONING ALT ALERTER OVERSHOOTS ASSIGNED ALT ON DSCNT.

Narrative: WE WERE CLRED TO 16000 FT. THE ALT ALERT DID NOT GO OFF AT 17000 FT. WE DSNDED THROUGH 16000 FT TO APPROX 15600 FT WHEN THE ALERTER WENT OFF AT 15700 FT. WE CLBED BACK UP TO 16000 FT IMMEDIATELY. ZDC ASKED US TO CONFIRM WE WERE AT 16000 FT AS WE WERE CLBING BACK UP THROUGH 15750 FT. I TOLD THE CTLR THAT WE WERE CLBING BACK TO 16000 FT AND THAT WE WERE THROUGH 15800 FT, WHICH WE WERE AT THAT TIME. ZDC LATER (5 MINS?) ADVISED US THAT 'THE MACHINE WENT OFF ON THAT ONE' AND THAT IT WOULD BE LOOKED INTO. THE ALT ALERT HAD BEEN ERRATIC ALL DAY, BUT WAS MOST ERRATIC ON THIS FLT. WE HAD FLOWN THE PLANE FOR 6 LEGS AND THE ALERTER HAD GONE OFF AT ODD ALTS BUT HADN'T MISSED AN ALT YET, IE, IT WENT OFF AT 10000 FT WHEN CLRED TO 6000 FT AND AT FL180 WHEN CLRED TO AN ALT LOWER THAN 17000 FT, BUT IT HAD NOT FAILED TO GO OFF 1000 FT ABOVE, BEFORE THIS INSTANCE. THE TCASII SYS WAS NOT WORKING AND MEL'ED.

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.