C172 pilot missed qnh by 1 inch in N90 class east.

Attributes
ACN	581867
Time
Date	200305
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : cmk.vor
State Reference	NY
Altitude	msl single value : 4000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90.tracon
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Navigation In Use	other vortac
Flight Phase	climbout : initial climbout : intermediate altitude
Route In Use	departure sid : westchester
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot oversight : pic
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 55 flight time total : 210 flight time type : 140
ASRS Report	581867
Person 2
Affiliation	government : faa
Function	controller : departure controller : approach
Events
Anomaly	altitude deviation : overshoot inflight encounter : weather inflight encounter other non adherence : far non adherence : published procedure other anomaly other
Independent Detector	atc equipment other atc equipment : mode c other controllera
Resolutory Action	controller : issued advisory flight crew : returned to assigned altitude
Supplementary
Problem Areas	Weather Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was cleared on the westchester 1 departure from hpn. Cleared to maintain 3000 ft, I inadvertently climbed to 4000 ft. The controller questioned me about this, and I realized what had happened. My altimeter did read 3000 ft, but I realized that the wrong altimeter setting had been inputted, thus giving me a false altimeter reading of 1000 ft too low. This was human error on my part. On the ground, I did monitor the ATIS, and I did input the altimeter setting I heard, but I entered it incorrectly. I also misread the altimeter. I thought it showed 480 ft, but actually, it was reading -480 ft. I did question the 480 as the known field elevation was 400 ft. I figured the local altimeter setting had changed as the ATIS was almost an hour old. I didn't count on misreading the altimeter, and I should have asked ATC for a new altimeter setting. Unfortunately, the incorrectly inputted altimeter setting too closely resembled the field elevation in hundreds. In retrospect, after takeoff and on a downwind departure, as I passed through 1000 ft, I thought I seemed higher above the runway environment, but I didn't make the connection. There was no way I was going to pick up the mistake once I was airborne. I feel embarrassed and depressed about this, as it could have resulted in serious injury to myself and others. I need to be more careful about routine tasks like inputting altimeter settings, and I need to doublechk everything, which I will do in the future.

Original NASA ASRS Text

Title: C172 PLT MISSED QNH BY 1 INCH IN N90 CLASS E.

Narrative: I WAS CLRED ON THE WESTCHESTER 1 DEP FROM HPN. CLRED TO MAINTAIN 3000 FT, I INADVERTENTLY CLBED TO 4000 FT. THE CTLR QUESTIONED ME ABOUT THIS, AND I REALIZED WHAT HAD HAPPENED. MY ALTIMETER DID READ 3000 FT, BUT I REALIZED THAT THE WRONG ALTIMETER SETTING HAD BEEN INPUTTED, THUS GIVING ME A FALSE ALTIMETER READING OF 1000 FT TOO LOW. THIS WAS HUMAN ERROR ON MY PART. ON THE GND, I DID MONITOR THE ATIS, AND I DID INPUT THE ALTIMETER SETTING I HEARD, BUT I ENTERED IT INCORRECTLY. I ALSO MISREAD THE ALTIMETER. I THOUGHT IT SHOWED 480 FT, BUT ACTUALLY, IT WAS READING -480 FT. I DID QUESTION THE 480 AS THE KNOWN FIELD ELEVATION WAS 400 FT. I FIGURED THE LCL ALTIMETER SETTING HAD CHANGED AS THE ATIS WAS ALMOST AN HR OLD. I DIDN'T COUNT ON MISREADING THE ALTIMETER, AND I SHOULD HAVE ASKED ATC FOR A NEW ALTIMETER SETTING. UNFORTUNATELY, THE INCORRECTLY INPUTTED ALTIMETER SETTING TOO CLOSELY RESEMBLED THE FIELD ELEVATION IN HUNDREDS. IN RETROSPECT, AFTER TKOF AND ON A DOWNWIND DEP, AS I PASSED THROUGH 1000 FT, I THOUGHT I SEEMED HIGHER ABOVE THE RWY ENVIRONMENT, BUT I DIDN'T MAKE THE CONNECTION. THERE WAS NO WAY I WAS GOING TO PICK UP THE MISTAKE ONCE I WAS AIRBORNE. I FEEL EMBARRASSED AND DEPRESSED ABOUT THIS, AS IT COULD HAVE RESULTED IN SERIOUS INJURY TO MYSELF AND OTHERS. I NEED TO BE MORE CAREFUL ABOUT ROUTINE TASKS LIKE INPUTTING ALTIMETER SETTINGS, AND I NEED TO DOUBLECHK EVERYTHING, WHICH I WILL DO IN THE FUTURE.

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.