Possible intrusion into class 'B' airspace.

Attributes
ACN	324558
Time
Date	199512
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : 0a6
State Reference	NC
Altitude	msl bound lower : 1680 msl bound upper : 1760
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	VFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 30 flight time total : 480 flight time type : 420
ASRS Report	324558
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We departed 0a6 for a flight direct to lkr at an altitude of approximately 1700 ft MSL. 1700 ft MSL was chosen so as to stay clear of clt class B airspace in the path of flight. We had set our altitude to the field elevation of 0a6 and felt confident that 1700 ft MSL was clear of class B. During our first phase of flight under class B we stayed between 1760 ft and 1680 ft MSL. When we felt we were clear of class B airspace we then climbed to 2000 ft MSL for the flight to lkr. Our climb was initiated approximately 5 mi from rockhill airport. At no time did we purposely enter class B airspace. Our concern stems from the possibility that our mode C encoder showed our altitude to be greater than or equal to 1800 ft MSL in class B airspace when in reality our altimeter showed less than 1800 ft MSL.

Original NASA ASRS Text

Title: POSSIBLE INTRUSION INTO CLASS 'B' AIRSPACE.

Narrative: WE DEPARTED 0A6 FOR A FLT DIRECT TO LKR AT AN ALT OF APPROX 1700 FT MSL. 1700 FT MSL WAS CHOSEN SO AS TO STAY CLR OF CLT CLASS B AIRSPACE IN THE PATH OF FLT. WE HAD SET OUR ALT TO THE FIELD ELEVATION OF 0A6 AND FELT CONFIDENT THAT 1700 FT MSL WAS CLR OF CLASS B. DURING OUR FIRST PHASE OF FLT UNDER CLASS B WE STAYED BTWN 1760 FT AND 1680 FT MSL. WHEN WE FELT WE WERE CLR OF CLASS B AIRSPACE WE THEN CLBED TO 2000 FT MSL FOR THE FLT TO LKR. OUR CLB WAS INITIATED APPROX 5 MI FROM ROCKHILL ARPT. AT NO TIME DID WE PURPOSELY ENTER CLASS B AIRSPACE. OUR CONCERN STEMS FROM THE POSSIBILITY THAT OUR MODE C ENCODER SHOWED OUR ALT TO BE GREATER THAN OR EQUAL TO 1800 FT MSL IN CLASS B AIRSPACE WHEN IN REALITY OUR ALTIMETER SHOWED LESS THAN 1800 FT MSL.

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.