Narrative:

Approaching dover (dov) I felt that there was no need to transition the dov class D airspace before climbing and decided to avoid that airspace by flying northwest. I contacted dover approach for radar advisories and was told to contact dover tower. The tower controller admonished me for entering class D airspace without first establishing radio communications. I replied that my GPS moving map had me positioned outside class D airspace though he contended I was .5 mi inside. Resolution of this problem in my case would appear being conservative regarding interping moving map information and erring on the wide side airspace boundaries. Callback conversation with reporter revealed the following information: reporter advised that HSI GPS system is an older unit from a vendor no longer actively engaged in providing hardware to the aviation community. He nonetheless is able to update his database regularly from a commercial database supplier. This GPS unit was digitally connected to another vendor's moving map display. He stated he was not aware that the class D areas generated from that database were not a geometrically accurate depiction of the actual tailored airspace. He further stated that nowhere in the documentation for his unit was there any mention that the class D's displayed were not intended to be accurate representations. He also did not recall any disclaimer in the GPS documentation regarding the appropriateness of using the unit as the sole source of navigation information.

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Original NASA ASRS Text

Title: PLT OF C177, UTILIZING GPS MOVING MAP DISPLAY FOR VFR NAV PURPOSES ENTERED THE DOV CLASS D AIRSPACE NOTWITHSTANDING THE GPS INDICATION OF NOT DOING SO.

Narrative: APCHING DOVER (DOV) I FELT THAT THERE WAS NO NEED TO TRANSITION THE DOV CLASS D AIRSPACE BEFORE CLBING AND DECIDED TO AVOID THAT AIRSPACE BY FLYING NW. I CONTACTED DOVER APCH FOR RADAR ADVISORIES AND WAS TOLD TO CONTACT DOVER TWR. THE TWR CTLR ADMONISHED ME FOR ENTERING CLASS D AIRSPACE WITHOUT FIRST ESTABLISHING RADIO COMS. I REPLIED THAT MY GPS MOVING MAP HAD ME POSITIONED OUTSIDE CLASS D AIRSPACE THOUGH HE CONTENDED I WAS .5 MI INSIDE. RESOLUTION OF THIS PROB IN MY CASE WOULD APPEAR BEING CONSERVATIVE REGARDING INTERPING MOVING MAP INFO AND ERRING ON THE WIDE SIDE AIRSPACE BOUNDARIES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ADVISED THAT HSI GPS SYS IS AN OLDER UNIT FROM A VENDOR NO LONGER ACTIVELY ENGAGED IN PROVIDING HARDWARE TO THE AVIATION COMMUNITY. HE NONETHELESS IS ABLE TO UPDATE HIS DATABASE REGULARLY FROM A COMMERCIAL DATABASE SUPPLIER. THIS GPS UNIT WAS DIGITALLY CONNECTED TO ANOTHER VENDOR'S MOVING MAP DISPLAY. HE STATED HE WAS NOT AWARE THAT THE CLASS D AREAS GENERATED FROM THAT DATABASE WERE NOT A GEOMETRICALLY ACCURATE DEPICTION OF THE ACTUAL TAILORED AIRSPACE. HE FURTHER STATED THAT NOWHERE IN THE DOCUMENTATION FOR HIS UNIT WAS THERE ANY MENTION THAT THE CLASS D'S DISPLAYED WERE NOT INTENDED TO BE ACCURATE REPRESENTATIONS. HE ALSO DID NOT RECALL ANY DISCLAIMER IN THE GPS DOCUMENTATION REGARDING THE APPROPRIATENESS OF USING THE UNIT AS THE SOLE SOURCE OF NAV INFO.

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.