A319 flight crew overshot leveloff while the PF was programming the FMGS.

Attributes
ACN	783300
Time
Date	200804
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : phl.airport
State Reference	PA
Altitude	msl single value : 8000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : phl.tracon
Operator	common carrier : air carrier
Make Model Name	A319
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival star : n/s
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 19535 flight time type : 2400
ASRS Report	783300
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Captain flying in managed descent to 8000 ft leveling off 5 NM from vcn VOR; phl approach issued heading 330 degrees for radar vectors to visual runway 27R phl. 250 KTS was selected. While clearing STAR and programming FMGC for ILS runway 27L phl; I noticed that aircraft was descending through 7700 ft and altitude in FMS had changed to 7000 ft for unknown reason. I stopped descent and returned to 8000 ft just as phl approach asked what altitude we were descending to. There was not a conflict. Selecting heading; airspeed; and heads down programming FMGC contributed to not noticing aircraft failed to level at 8000 ft.

Original NASA ASRS Text

Title: A319 FLT CREW OVERSHOT LEVELOFF WHILE THE PF WAS PROGRAMMING THE FMGS.

Narrative: CAPT FLYING IN MANAGED DSCNT TO 8000 FT LEVELING OFF 5 NM FROM VCN VOR; PHL APCH ISSUED HDG 330 DEGS FOR RADAR VECTORS TO VISUAL RWY 27R PHL. 250 KTS WAS SELECTED. WHILE CLRING STAR AND PROGRAMMING FMGC FOR ILS RWY 27L PHL; I NOTICED THAT ACFT WAS DSNDING THROUGH 7700 FT AND ALT IN FMS HAD CHANGED TO 7000 FT FOR UNKNOWN REASON. I STOPPED DSCNT AND RETURNED TO 8000 FT JUST AS PHL APCH ASKED WHAT ALT WE WERE DSNDING TO. THERE WAS NOT A CONFLICT. SELECTING HDG; AIRSPD; AND HEADS DOWN PROGRAMMING FMGC CONTRIBUTED TO NOT NOTICING ACFT FAILED TO LEVEL AT 8000 FT.

Data retrieved from NASA's ASRS site as of May 2009 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.