MD80 crew had altitude overshoot in pit class east.

Attributes
ACN	491950
Time
Date	200011
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : pit.airport
State Reference	PA
Altitude	msl bound lower : 12725 msl bound upper : 13000
Environment
Flight Conditions	IMC
Weather Elements	Rain other
Light	Night
Aircraft 1
Controlling Facilities	tracon : pit.tracon
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 18500 flight time type : 8500
ASRS Report	491950
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : overshoot inflight encounter : weather inflight encounter other non adherence : published procedure other anomaly other
Independent Detector	atc equipment other atc equipment : radar other controllera
Resolutory Action	controller : issued alert flight crew : returned to assigned altitude none taken : detected after the fact
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance Weather
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

En route from clt to pit descended in vicinity of ekn, was given altimeter 29.75, (descending to 13000 ft). ATC handed us over to approach to pit just north of mgw. Several mins approach advised that we were low and to adjust altimeter to 29.45. After adjusting our altimeters read 12725 ft. A large low pressure system over pit area had caused a steep gradient in atmospheric pressure. After resetting altimeters we climbed back to 13000 ft.

Original NASA ASRS Text

Title: MD80 CREW HAD ALT OVERSHOOT IN PIT CLASS E.

Narrative: ENRTE FROM CLT TO PIT DSNDED IN VICINITY OF EKN, WAS GIVEN ALTIMETER 29.75, (DSNDING TO 13000 FT). ATC HANDED US OVER TO APCH TO PIT JUST N OF MGW. SEVERAL MINS APCH ADVISED THAT WE WERE LOW AND TO ADJUST ALTIMETER TO 29.45. AFTER ADJUSTING OUR ALTIMETERS READ 12725 FT. A LARGE LOW PRESSURE SYS OVER PIT AREA HAD CAUSED A STEEP GRADIENT IN ATMOSPHERIC PRESSURE. AFTER RESETTING ALTIMETERS WE CLBED BACK TO 13000 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.