Transponders are not a magic shield.

I fly with a Mode S transponder in the busy Philadelphia / New York
airspace. I often see airliners diverting course to go around me
(particularly commuters), but then there was the Southwest 737 that
flew 300 feet directly over me. I was thermalling at 5700, he was
straight and level at 6000. Gliders in this area have a discrete
transponder code, and we know from conversations with ATC that they're
keeping track of us specifically as glider traffic. So, I know for
certain that (1) the Southwest pilot was aware of me (long before I
was aware of him), and (2) he was also aware that I was a glider.

I'm not standing on principle here, if I'd seen him sooner I would
have quit thermalling and flown 90 degrees to his track while losing
altitude (quickly). But it was a hazy day, I was thermalling, he was
doing 250 kts, and I just flat didn't see him until he was about a
mile away.

Moral - keep a good lookout, amd remember that stuff can happen in
spite of a transponder...

-John

On Sep 8, 1:56 pm, Ramy wrote:
Since I started flying with transponders I never
saw an airliner too close, and I am flying in some of the most busy
airspaces in the US (Bay Area and Reno).