On Wed, 14 Sep 2005 16:15:54 GMT, "John Kirksey"
wrote:

So we were watching "Seconds From Disaster" on NGC last night, which
happened to be on AA 77. When they mentioned that seconds after gaining
control of the aircraft the hijackers turned off the transponder (along with
a brief explanation of what the transponder does), my wife simply says:

"That's stupid, why does something like that even have an on/off switch?"

I honestly never thought about it and couldn't answer her question. Does
anyone know?

Regards,

John K.



You need the ability to turn off the xponder inflight. One day I was
flying along and ATC called and asked me if anything was wrong. I said
everything is fine, why do you ask? They told me my xponder was
transmitting 7700. I looked at the xponder and confirmed that was NOT
what I have set - they said please turn it off - so I did.

When I'm on the ground, I set my xponder to standby, not off.

Ralph