First officer of a DC9-30 overshot descent intermediate altitude when becoming distraction.

Attributes
ACN	474330
Time
Date	200005
Day	Mon
Local Time Of Day	1801 To 2400
Place
State Reference	DE
Altitude	msl bound lower : 3700 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : phl.tracon
Operator	common carrier : air carrier
Make Model Name	DC-9 30
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 14000 flight time type : 800
ASRS Report	474330
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine pilot : instrument
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued alert flight crew : returned to assigned altitude
Consequence	Other
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were on descent to phl, being vectored by approach control, cleared to 4000 ft. It was a clear night and the first officer, who was flying the aircraft on autoplt, asked if I knew the name of the airport on the nose. I said I thought it was wilmington, and we both commented on how bright the runway lights were. Suddenly we noticed we were passing 4000 ft, still descending. The first officer was using the vertical speed wheel on the autoplt. The aircraft was slow to respond to the inputs so the autoplt was disconnected and the aircraft was hand flown back up to 4000 ft. As the descent was halted, I heard the altitude warning horn sound, so we must have gotten down to 3700 ft. At the same time, approach control confirmed our clearance was 4000 ft and called traffic at 2 O'clock and 8 1/2 mi at 3000 ft. I think the main contributing factor was that approach control was unusually quiet. It seemed like we were the only ones flying, and we allowed ourselves to relax and divert our attention from the task at hand.

Original NASA ASRS Text

Title: FO OF A DC9-30 OVERSHOT DSCNT INTERMEDIATE ALT WHEN BECOMING DISTR.

Narrative: WE WERE ON DSCNT TO PHL, BEING VECTORED BY APCH CTL, CLRED TO 4000 FT. IT WAS A CLR NIGHT AND THE FO, WHO WAS FLYING THE ACFT ON AUTOPLT, ASKED IF I KNEW THE NAME OF THE ARPT ON THE NOSE. I SAID I THOUGHT IT WAS WILMINGTON, AND WE BOTH COMMENTED ON HOW BRIGHT THE RWY LIGHTS WERE. SUDDENLY WE NOTICED WE WERE PASSING 4000 FT, STILL DSNDING. THE FO WAS USING THE VERT SPD WHEEL ON THE AUTOPLT. THE ACFT WAS SLOW TO RESPOND TO THE INPUTS SO THE AUTOPLT WAS DISCONNECTED AND THE ACFT WAS HAND FLOWN BACK UP TO 4000 FT. AS THE DSCNT WAS HALTED, I HEARD THE ALT WARNING HORN SOUND, SO WE MUST HAVE GOTTEN DOWN TO 3700 FT. AT THE SAME TIME, APCH CTL CONFIRMED OUR CLRNC WAS 4000 FT AND CALLED TFC AT 2 O'CLOCK AND 8 1/2 MI AT 3000 FT. I THINK THE MAIN CONTRIBUTING FACTOR WAS THAT APCH CTL WAS UNUSUALLY QUIET. IT SEEMED LIKE WE WERE THE ONLY ONES FLYING, AND WE ALLOWED OURSELVES TO RELAX AND DIVERT OUR ATTN FROM THE TASK AT HAND.

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.