Narrative:

Upon departure off runway 32 at frg a climb to 2900 feet MSL was conducted for our flight northbound. Upon landing we were advised to call new york TRACON. TRACON advised that they showed us cruising at 3100 feet MSL which would have put our aircraft inside the class B airspace. At no time did the aircraft climb above 2900 indicated altitude. Altimeters were set and cross checked both before departure from frg and before arrival at [our destination] with the respective local barometric pressures. On the subsequent flight we asked TRACON for a mode C check while in cruise at 10;500 feet which agreed with our indicated altitude.

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Original NASA ASRS Text

Title: Citation pilot departing from FRG northbound at 2900 feet to avoid the New York Class B airspace is informed after landing that his mode C transponder indicated he was at 3100 feet and inside the Bravo.

Narrative: Upon departure off Runway 32 at FRG a climb to 2900 feet MSL was conducted for our flight northbound. Upon landing we were advised to call New York TRACON. TRACON advised that they showed us cruising at 3100 feet MSL which would have put our aircraft inside the Class B airspace. At no time did the aircraft climb above 2900 indicated altitude. Altimeters were set and cross checked both before departure from FRG and before arrival at [our destination] with the respective local barometric pressures. On the subsequent flight we asked TRACON for a mode C check while in cruise at 10;500 feet which agreed with our indicated Altitude.

Data retrieved from NASA's ASRS site 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.