Cessna pilot reported a malfunctioning GPS receiver.

Attributes
ACN	1682977
Time
Date	201909
Local Time Of Day	0601-1200
Place
Locale Reference	DFW.Airport
State Reference	TX
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Cessna Aircraft Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Descent
Flight Plan	None
Component
Aircraft Component	GPS & Other Satellite Navigation
Person 1
Function	Single Pilot
Qualification	Flight Crew Multiengine Flight Crew Flight Instructor Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Experience	Flight Crew Total 15600 Flight Crew Type 150
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Other / Unknown

Narrative:

During a local VFR flight on a clear weather day I was flying and my aircraft lost GPS signal to the avidyne ifd 500 instrument and might have affected the mode south transponder that is also linked together with waas GPS position. I did notice a message that the GPS position had lost signal on my ifd 500 panel mounted instrument; but I didn't realize during my flight that the mode south transponder may have been without GPS signal also which provides position and altitude to the local ATC radar. My flight had me flying 'below class B' airspace in the dfw area to my local airport. My two month old avionics upgrade to include IFR waas GPS and a remote mounted mode south transponder is still something I'm getting used to seeing the visual displays and all associated messages. After talking with my avionics shop and resetting the GPS and avidyne ifd 500 unit at our airport I realized the mode south transponder may not have been sending the proper info to the dfw 'regional approach' radar folks. In the future I feel the transponder itself should send a message to the pilot if it has lost GPS signal or better yet fail to the 'send position and altitude' mode south function straight from the GPS waas antenna if the ifd 550 display messes up.

Original NASA ASRS Text

Title: Cessna pilot reported a malfunctioning GPS receiver.

Narrative: During a local VFR flight on a clear weather day I was flying and my aircraft lost GPS signal to the Avidyne IFD 500 instrument and might have affected the Mode S transponder that is also linked together with WAAS GPS position. I did notice a message that the GPS position had lost signal on my IFD 500 panel mounted instrument; but I didn't realize during my flight that the Mode S transponder may have been without GPS signal also which provides position and altitude to the local ATC radar. My flight had me flying 'Below Class B' airspace in the DFW area to my local airport. My two month old avionics upgrade to include IFR WAAS GPS and a remote mounted Mode S transponder is still something I'm getting used to seeing the visual displays and all associated messages. After talking with my avionics shop and resetting the GPS and Avidyne IFD 500 unit at our airport I realized the Mode S transponder may not have been sending the proper info to the DFW 'Regional Approach' radar folks. In the future I feel the transponder itself should send a message to the pilot if it has lost GPS signal or better yet fail to the 'send position and altitude' Mode S function straight from the GPS WAAS antenna if the IFD 550 display messes up.

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.