Narrative:

I was flying to placerville (pvf) and using my GPS to avoid violating airspace. I have 2 garmin 430's in my warrior III. I had just weaved my way between 2 other airspaces when I noticed that my second GPS was displaying an 'inside airspace' message. However; the airspace was not displayed on the GPS I had been using for primary guidance; and was not displaying and 'inside airspace' message. I turned and flew out of the airspace as quickly as I could. I am still not sure that I was actually in the airspace. I am pretty sure that I was at 2800 ft; so I should have been above the ceiling of the airspace. I have re-read my garmin manual and cannot find any information about why one unit would show the airspace on the map when the other unit did not display it. It may have something to do with the 'declutter' feature; but I have not found any specific information in the manual. There is also a 'cushion' built in to the airspace warnings that adds 500 ft to the airspace; but it is not clear from the manual whether I would have received an 'inside airspace' message if I was within the cushion but not the real airspace. I am continuing to investigate this to make sure it does not happen again. I will make a test flight with a safety pilot (and appropriate clrncs!) to test the cushion feature. I was being very careful to avoid airspace; and would not have entered the airspace had it been displayed on the GPS. Callback conversation with reporter revealed the following information: the reporter noted that he had subsequently experimented with the GPS units and learned that the presentation of restr airspace was not universally available on all zoom levels of the display. He advised restr airspace was only shown on zoom levels of 20 NM or less. He suggested that he may not have had the GPS which failed to display the warning in an appropriate zoom level. He did not know whether the lack of display of a restr airspace precludes the GPS aural and/or visual warning for entering same. He intends to contact the manufacturer suggesting that restr airspace display be given higher priority for displays at all levels of zoom. The normal inclination during cross country flight is to leave the display at larger displays which might not display the restr airspace; making inadvertent entry more likely.

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Original NASA ASRS Text

Title: PLT OF PA28 MAY HAVE ENTERED CLASS D AIRSPACE OF SAC WITHOUT CLRNC.

Narrative: I WAS FLYING TO PLACERVILLE (PVF) AND USING MY GPS TO AVOID VIOLATING AIRSPACE. I HAVE 2 GARMIN 430'S IN MY WARRIOR III. I HAD JUST WEAVED MY WAY BTWN 2 OTHER AIRSPACES WHEN I NOTICED THAT MY SECOND GPS WAS DISPLAYING AN 'INSIDE AIRSPACE' MESSAGE. HOWEVER; THE AIRSPACE WAS NOT DISPLAYED ON THE GPS I HAD BEEN USING FOR PRIMARY GUIDANCE; AND WAS NOT DISPLAYING AND 'INSIDE AIRSPACE' MESSAGE. I TURNED AND FLEW OUT OF THE AIRSPACE AS QUICKLY AS I COULD. I AM STILL NOT SURE THAT I WAS ACTUALLY IN THE AIRSPACE. I AM PRETTY SURE THAT I WAS AT 2800 FT; SO I SHOULD HAVE BEEN ABOVE THE CEILING OF THE AIRSPACE. I HAVE RE-READ MY GARMIN MANUAL AND CANNOT FIND ANY INFO ABOUT WHY ONE UNIT WOULD SHOW THE AIRSPACE ON THE MAP WHEN THE OTHER UNIT DID NOT DISPLAY IT. IT MAY HAVE SOMETHING TO DO WITH THE 'DECLUTTER' FEATURE; BUT I HAVE NOT FOUND ANY SPECIFIC INFO IN THE MANUAL. THERE IS ALSO A 'CUSHION' BUILT IN TO THE AIRSPACE WARNINGS THAT ADDS 500 FT TO THE AIRSPACE; BUT IT IS NOT CLR FROM THE MANUAL WHETHER I WOULD HAVE RECEIVED AN 'INSIDE AIRSPACE' MESSAGE IF I WAS WITHIN THE CUSHION BUT NOT THE REAL AIRSPACE. I AM CONTINUING TO INVESTIGATE THIS TO MAKE SURE IT DOES NOT HAPPEN AGAIN. I WILL MAKE A TEST FLT WITH A SAFETY PLT (AND APPROPRIATE CLRNCS!) TO TEST THE CUSHION FEATURE. I WAS BEING VERY CAREFUL TO AVOID AIRSPACE; AND WOULD NOT HAVE ENTERED THE AIRSPACE HAD IT BEEN DISPLAYED ON THE GPS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR NOTED THAT HE HAD SUBSEQUENTLY EXPERIMENTED WITH THE GPS UNITS AND LEARNED THAT THE PRESENTATION OF RESTR AIRSPACE WAS NOT UNIVERSALLY AVAILABLE ON ALL ZOOM LEVELS OF THE DISPLAY. HE ADVISED RESTR AIRSPACE WAS ONLY SHOWN ON ZOOM LEVELS OF 20 NM OR LESS. HE SUGGESTED THAT HE MAY NOT HAVE HAD THE GPS WHICH FAILED TO DISPLAY THE WARNING IN AN APPROPRIATE ZOOM LEVEL. HE DID NOT KNOW WHETHER THE LACK OF DISPLAY OF A RESTR AIRSPACE PRECLUDES THE GPS AURAL AND/OR VISUAL WARNING FOR ENTERING SAME. HE INTENDS TO CONTACT THE MANUFACTURER SUGGESTING THAT RESTR AIRSPACE DISPLAY BE GIVEN HIGHER PRIORITY FOR DISPLAYS AT ALL LEVELS OF ZOOM. THE NORMAL INCLINATION DURING XCOUNTRY FLT IS TO LEAVE THE DISPLAY AT LARGER DISPLAYS WHICH MIGHT NOT DISPLAY THE RESTR AIRSPACE; MAKING INADVERTENT ENTRY MORE LIKELY.

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.