AA5 pilot departs gai with incorrect altimeter setting.

Attributes
ACN	614335
Time
Date	200404
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bwi.airport
State Reference	MD
Altitude	msl single value : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pct.tracon
Operator	general aviation : personal
Make Model Name	Tiger (F11)
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	DVR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 5 flight time total : 1500 flight time type : 500
ASRS Report	614335
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	aircraft equipment problem : critical altitude deviation : undershoot non adherence : far
Independent Detector	other controllera
Resolutory Action	controller : issued advisory flight crew : became reoriented flight crew : overrode automation flight crew : returned to assigned altitude
Supplementary
Problem Areas	ATC Human Performance Airport Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Incorrectly set departure altimeter to 480 ft rather than 048 ft. Recently re-based to cgs (first flight after moving from gai). Field elevation at gai was 540 ft, so I was pre-conditioned to expect 'roughly' 500 ft. Unable to receive AWOS, so set altimeter using field elevation. Potomac did not catch or correct mode C discrepancy when I checked on and reported altitude leaving. Was asked to descend from 2500 ft to 2000 ft. When I checked on with next controller, the 500 ft discrepancy was caught and corrected. Error caused by misreading chart and contributing factor was failure of first potomac controller to verify mode C readout.

Original NASA ASRS Text

Title: AA5 PLT DEPARTS GAI WITH INCORRECT ALTIMETER SETTING.

Narrative: INCORRECTLY SET DEP ALTIMETER TO 480 FT RATHER THAN 048 FT. RECENTLY RE-BASED TO CGS (FIRST FLT AFTER MOVING FROM GAI). FIELD ELEVATION AT GAI WAS 540 FT, SO I WAS PRE-CONDITIONED TO EXPECT 'ROUGHLY' 500 FT. UNABLE TO RECEIVE AWOS, SO SET ALTIMETER USING FIELD ELEVATION. POTOMAC DID NOT CATCH OR CORRECT MODE C DISCREPANCY WHEN I CHKED ON AND RPTED ALT LEAVING. WAS ASKED TO DSND FROM 2500 FT TO 2000 FT. WHEN I CHKED ON WITH NEXT CTLR, THE 500 FT DISCREPANCY WAS CAUGHT AND CORRECTED. ERROR CAUSED BY MISREADING CHART AND CONTRIBUTING FACTOR WAS FAILURE OF FIRST POTOMAC CTLR TO VERIFY MODE C READOUT.

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.