B727 PIC overshoots his assigned altitude while on autoplt descent over rbv, nj.

Attributes
ACN	509050
Time
Date	200104
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : rbv.vortac
State Reference	NJ
Altitude	msl bound lower : 7500 msl bound upper : 8000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Flight Phase	descent : intermediate altitude descent : holding
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : multi engine pilot : private pilot : instrument pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 220 flight time total : 5000 flight time type : 1000
ASRS Report	509050
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance non adherence : published procedure
Resolutory Action	flight crew : became reoriented flight crew : returned to assigned altitude flight crew : overrode automation
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	FAA
Air Traffic Incident	Pilot Deviation

Narrative:

On the robinsville 1 arrival into ewr, we were on autoplt and given a descent to 8000 ft MSL. Over rbv, altitude alert sounded. I looked up and noticed altitude descending through 7600 ft MSL. Told the captain our clearance was to 8000 ft. He disengaged the autoplt and climbed back to 8000 ft. The lowest altitude I saw as 7500 ft.

Original NASA ASRS Text

Title: B727 PIC OVERSHOOTS HIS ASSIGNED ALT WHILE ON AUTOPLT DSCNT OVER RBV, NJ.

Narrative: ON THE ROBINSVILLE 1 ARR INTO EWR, WE WERE ON AUTOPLT AND GIVEN A DSCNT TO 8000 FT MSL. OVER RBV, ALT ALERT SOUNDED. I LOOKED UP AND NOTICED ALT DSNDING THROUGH 7600 FT MSL. TOLD THE CAPT OUR CLRNC WAS TO 8000 FT. HE DISENGAGED THE AUTOPLT AND CLBED BACK TO 8000 FT. THE LOWEST ALT I SAW AS 7500 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.