Narrative:

I departed dayton moraine wbound climbing to 3000 ft MSL. My cruise heading would be 315 degrees, however, I went west so I could cross the runway 6 localizer (day) several mi out. I was 4-6 mi outside of the day arsa at all times, when about 8 mi west of moraine, I turned to 315 degrees. I was on 122.7 with day approach in the standby frequency. As I got on the localizer to cross it, I saw a large aircraft 15 degrees to the right of my nose and same altitude (3000 ft). As I knew he was tracking or intercepting the localizer, I climbed and turned left to 270 degrees. Other aircraft passed below and to right. As I turned, I brought up day approach. I heard the controller tell the medium large transport he went through the localizer. The medium large transport said he was watching the 'little guy' and missed the localizer. I saw and avoided the other aircraft safely. If I had the approach control frequency active, I would have known his location before I saw him. I suspect the other aircraft was on a training flight as it was severe clear and he was intercepting the localizer 14 mi out when you could see the airport 50 mi out. This is a CAT ii approach, with the other aircraft flying a missed approach. Why would an air carrier be 2900-3000 ft when 14 1/2 mi from the airport in a high density GA environment? The other aircraft did not have his approach or landing lights on, which made it harder to see him. I suspect the other aircraft entered the arsa at or below the 2400 floor at its outer ring. When I was inbound to moraine, the dayton traffic was only cleared down to 4000 ft in this area. All aircraft should have lights on in high traffic areas.

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Original NASA ASRS Text

Title: POTENTIAL CONFLICT AVOIDED AS SMA PERFORMS EVASIVE ACTION CLB.

Narrative: I DEPARTED DAYTON MORAINE WBOUND CLBING TO 3000 FT MSL. MY CRUISE HDG WOULD BE 315 DEGS, HOWEVER, I WENT W SO I COULD CROSS THE RWY 6 LOC (DAY) SEVERAL MI OUT. I WAS 4-6 MI OUTSIDE OF THE DAY ARSA AT ALL TIMES, WHEN ABOUT 8 MI W OF MORAINE, I TURNED TO 315 DEGS. I WAS ON 122.7 WITH DAY APCH IN THE STANDBY FREQ. AS I GOT ON THE LOC TO CROSS IT, I SAW A LARGE ACFT 15 DEGS TO THE R OF MY NOSE AND SAME ALT (3000 FT). AS I KNEW HE WAS TRACKING OR INTERCEPTING THE LOC, I CLBED AND TURNED L TO 270 DEGS. OTHER ACFT PASSED BELOW AND TO R. AS I TURNED, I BROUGHT UP DAY APCH. I HEARD THE CTLR TELL THE MLG HE WENT THROUGH THE LOC. THE MLG SAID HE WAS WATCHING THE 'LITTLE GUY' AND MISSED THE LOC. I SAW AND AVOIDED THE OTHER ACFT SAFELY. IF I HAD THE APCH CTL FREQ ACTIVE, I WOULD HAVE KNOWN HIS LOCATION BEFORE I SAW HIM. I SUSPECT THE OTHER ACFT WAS ON A TRAINING FLT AS IT WAS SEVERE CLR AND HE WAS INTERCEPTING THE LOC 14 MI OUT WHEN YOU COULD SEE THE ARPT 50 MI OUT. THIS IS A CAT II APCH, WITH THE OTHER ACFT FLYING A MISSED APCH. WHY WOULD AN ACR BE 2900-3000 FT WHEN 14 1/2 MI FROM THE ARPT IN A HIGH DENSITY GA ENVIRONMENT? THE OTHER ACFT DID NOT HAVE HIS APCH OR LNDG LIGHTS ON, WHICH MADE IT HARDER TO SEE HIM. I SUSPECT THE OTHER ACFT ENTERED THE ARSA AT OR BELOW THE 2400 FLOOR AT ITS OUTER RING. WHEN I WAS INBOUND TO MORAINE, THE DAYTON TFC WAS ONLY CLRED DOWN TO 4000 FT IN THIS AREA. ALL ACFT SHOULD HAVE LIGHTS ON IN HIGH TFC AREAS.

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.