Near midair collision between GA-small aircraft and air carrier-small transport.

Attributes
ACN	85894
Time
Date	198804
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : jfk airport : frg
State Reference	NY
Altitude	msl bound lower : 5600 msl bound upper : 6000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Flight Plan	None
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Plan	IFR
Person 1
Affiliation	Other
Qualification	pilot : commercial pilot : instrument pilot : cfi
Experience	flight time last 90 days : 100 flight time total : 990 flight time type : 150
ASRS Report	85894
Person 2
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude conflict : nmac non adherence : clearance
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	Other
Miss Distance	horizontal : 200 vertical : 400
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation other

Narrative:

My altimeter was set at current setting and reading 5500' (my assigned altitude). Ny departure called and reminded me my altitude was 5500'. I confirmed setting and reading as 5500'. Two mins later an small transport passed overhead and to my right. Ny departure said my squawk was showing 5800'. On continuing the flight, I made several more checks with other approach controls and no one else reported any unusual readouts. After landing at farmingdale, ny my altimeter read 20' below field elevation. Apparently my readout was off. I'm not sure why the small transport passed so close unless he had another altimeter setting.

Original NASA ASRS Text

Title: NMAC BETWEEN GA-SMA AND ACR-SMT.

Narrative: MY ALTIMETER WAS SET AT CURRENT SETTING AND READING 5500' (MY ASSIGNED ALT). NY DEP CALLED AND REMINDED ME MY ALT WAS 5500'. I CONFIRMED SETTING AND READING AS 5500'. TWO MINS LATER AN SMT PASSED OVERHEAD AND TO MY RIGHT. NY DEP SAID MY SQUAWK WAS SHOWING 5800'. ON CONTINUING THE FLT, I MADE SEVERAL MORE CHKS WITH OTHER APCH CTLS AND NO ONE ELSE RPTED ANY UNUSUAL READOUTS. AFTER LNDG AT FARMINGDALE, NY MY ALTIMETER READ 20' BELOW FIELD ELEVATION. APPARENTLY MY READOUT WAS OFF. I'M NOT SURE WHY THE SMT PASSED SO CLOSE UNLESS HE HAD ANOTHER ALTIMETER SETTING.

Data retrieved from NASA's ASRS site as of August 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.