Narrative:

I was on a ferry flight taking a C172G around the south side of ZZZ airspace and later around the north side of [restricted airspace] to ZZZ1 to have an inoperative ads-B transponder fixed. The aircraft did not have any operative transponder of any kind for this flight and as a result I planned a course to avoid any controlled airspace. Departure was uneventful as was the short climb to 3500 feet heading southeast. I was visually scanning 180 degrees in front of me every couple minutes and fine tuning my course around ZZZ airspace via an ipad on a ram mount on the yoke and a panel mounted GPS. I was double checking my course on the GPS when I noticed a flash of movement out my left window and below me. Crossing directly under me 50 ft. Maybe less was a white DA40NG. I was also able to clearly identify the emblem of [FBO] shortly after the passage. I did not observe any maneuvers on their part for the 10-15 seconds after the passage before I proceeded to look for any additional aircraft. There is a chance they changed course after I started looking for other aircraft I might have missed as this close call made me question the quality of my scan and as such I increased my frequency of my traffic scan. Based on the 90 degree angle they passed and the fact they were below me makes me theorize my right wing strut likely blocked direct view of them and prevented me from spotting them earlier and initiating course change or evasive action as required. I did not hear any radio calls on the unicom frequency for the two nearest airports which I was monitoring. I am aware of the equipment in these DA40NGs and hearing from students who attend the program feel there was an over-reliance on the twas system in the DA40NG and as such miss non-transponder equip aircraft. For myself I feel I should have factored in the blind spots caused by the wing struts and as such performed a slight wing rock during my scan to temporarily eliminate the blind spot to ensure I did not miss an aircraft it was blocking.

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Original NASA ASRS Text

Title: Private pilot reported a near mid-air collision in cruise while ferrying C-172 with inoperative transponder.

Narrative: I was on a ferry flight taking a C172G around the south side of ZZZ airspace and later around the north side of [Restricted Airspace] to ZZZ1 to have an inoperative ADS-B transponder fixed. The aircraft did not have any operative transponder of any kind for this flight and as a result I planned a course to avoid any controlled airspace. Departure was uneventful as was the short climb to 3500 feet heading southeast. I was visually scanning 180 degrees in front of me every couple minutes and fine tuning my course around ZZZ airspace via an iPad on a RAM mount on the yoke and a panel mounted GPS. I was double checking my course on the GPS when I noticed a flash of movement out my left window and below me. Crossing directly under me 50 ft. maybe less was a white DA40NG. I was also able to clearly identify the emblem of [FBO] shortly after the passage. I did not observe any maneuvers on their part for the 10-15 seconds after the passage before I proceeded to look for any additional aircraft. There is a chance they changed course after I started looking for other aircraft I might have missed as this close call made me question the quality of my scan and as such I increased my frequency of my traffic scan. Based on the 90 degree angle they passed and the fact they were below me makes me theorize my right wing strut likely blocked direct view of them and prevented me from spotting them earlier and initiating course change or evasive action as required. I did not hear any radio calls on the UNICOM frequency for the two nearest airports which I was monitoring. I am aware of the equipment in these DA40NGs and hearing from students who attend the program feel there was an over-reliance on the TWAS system in the DA40NG and as such miss non-transponder equip aircraft. For myself I feel I should have factored in the blind spots caused by the wing struts and as such performed a slight wing rock during my scan to temporarily eliminate the blind spot to ensure I did not miss an aircraft it was blocking.

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.