A few months ago I would have agreed with John Cochrane and just let it go when he said: "Transponders lets the FAA and airliners avoid me. That's very important where I fly since Midway approach seems to love to blast airliners through 20 miles of congested class E airspace right over our club at 4000'. But now I know that there is more to it.

I fly near the Class B airspace of PHL and EWR, and have been using a transponder for 5 years. For 4 of those years I've been pleased, as I've seen some airliners (mostly commuters but a few big guys, too) make slight course diversions to avoid me while I was thermalling. Clearly they saw me on their TCAS. But in late March I found out that EWR ATC either filtered out my 1202 squawk or just ignored it, as suddenly I found myself 500 feet below a 747 doing 250 kt. Turned out I was inadvertently flying under an approach path to EWR outside the Class B airspace (I certainly won't be flying near it again)! I'm sure the 747 saw me on his TCAS, but have since found out that he would only deviate if he'd gotten a RA, otherwise he'd be in trouble with ATC.

There are two lessons I learned from this. First, a PowerFLARM and a transponder won't prevent you from getting way too close to other traffic, even if they are under ATC control and have TCAS. Second, if you are a VFR pilot flying outside Class B airspace, you need to educate yourself on likely approach and departure routes that lie outside the Class B, and be very alert and careful if you get near them.

-John, Q3