Narrative:

While approaching the houston class B airspace from the east at 2500 ft MSL; the class B ring floor/ceiling information was referenced from a GPS connected laptop computer program named vista version 3.90. The information provided indicated the floor of the second ring to the north of iah was 3000 ft MSL and the ceiling 10000 ft MSL. When the tower controller indicated the correct class B airspace parameters in that location to be a floor of 2000 ft and a ceiling of 10000 ft; the aircraft descended below the class B and landed dwh without incident or request to communicate with airspace auths. Later reference to the houston sectional confirmed the tower information as correct. Afterthoughts: this error would not have occurred if the houston sectional had been the selected map type; rather than the world map used. Callback conversation with reporter revealed the following information: pilot stated that the software manufacturer provides a general disclaimer about the accuracy and validity of this information. The reporter did in fact call the manufacturer after this incident and was told that only so much information could be provided for a given task and the algorithm determined the amount of information necessary. For general use in this geographical area; therefore; some non critical information was withheld because it was deemed unimportant. The user was advised to use the full 'official' overlay if more detail is necessary. User felt the lesson to be learned is that all electronic navaids are subject to operator error; so user beware.

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Original NASA ASRS Text

Title: A BE25 PLT INCURRED ON IAH CLASS B AIRSPACE BECAUSE HE SELECTED THE INCORRECT MAP TYPE ON A LAPTOP GPS NAV SYS.

Narrative: WHILE APCHING THE HOUSTON CLASS B AIRSPACE FROM THE E AT 2500 FT MSL; THE CLASS B RING FLOOR/CEILING INFO WAS REFED FROM A GPS CONNECTED LAPTOP COMPUTER PROGRAM NAMED VISTA VERSION 3.90. THE INFO PROVIDED INDICATED THE FLOOR OF THE SECOND RING TO THE N OF IAH WAS 3000 FT MSL AND THE CEILING 10000 FT MSL. WHEN THE TWR CTLR INDICATED THE CORRECT CLASS B AIRSPACE PARAMETERS IN THAT LOCATION TO BE A FLOOR OF 2000 FT AND A CEILING OF 10000 FT; THE ACFT DSNDED BELOW THE CLASS B AND LANDED DWH WITHOUT INCIDENT OR REQUEST TO COMMUNICATE WITH AIRSPACE AUTHS. LATER REF TO THE HOUSTON SECTIONAL CONFIRMED THE TWR INFO AS CORRECT. AFTERTHOUGHTS: THIS ERROR WOULD NOT HAVE OCCURRED IF THE HOUSTON SECTIONAL HAD BEEN THE SELECTED MAP TYPE; RATHER THAN THE WORLD MAP USED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: PLT STATED THAT THE SOFTWARE MANUFACTURER PROVIDES A GENERAL DISCLAIMER ABOUT THE ACCURACY AND VALIDITY OF THIS INFO. THE RPTR DID IN FACT CALL THE MANUFACTURER AFTER THIS INCIDENT AND WAS TOLD THAT ONLY SO MUCH INFO COULD BE PROVIDED FOR A GIVEN TASK AND THE ALGORITHM DETERMINED THE AMOUNT OF INFO NECESSARY. FOR GENERAL USE IN THIS GEOGRAPHICAL AREA; THEREFORE; SOME NON CRITICAL INFO WAS WITHHELD BECAUSE IT WAS DEEMED UNIMPORTANT. THE USER WAS ADVISED TO USE THE FULL 'OFFICIAL' OVERLAY IF MORE DETAIL IS NECESSARY. USER FELT THE LESSON TO BE LEARNED IS THAT ALL ELECTRONIC NAVAIDS ARE SUBJECT TO OPERATOR ERROR; SO USER BEWARE.

Data retrieved from NASA's ASRS site as of January 2009 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.