"Larry Dighera" wrote in message
...
On Sun, 2 Jan 2005 11:31:26 -0600, "Marty"
wrote in ::


"Larry Dighera" wrote in message
. ..

Here's the MAC that lead to mandatory TCAS:
http://www.ntsb.gov/NTSB/brief.asp?e...13X34444&key=2


Correct Larry,

The thing that gets me is that this collision would still have happened
because,

"N4891F'S X-PONDER WASN'T DISPLAYED DUE TO EQUIP CONFIGURATION."

IOW, stand-by mode.


That's not the way I read the NTSB report. Here's the pertinent part:

INV REVEALED N4891F HAD INADVERTENTLY ENTERED THE LAX TERMINAL
CONTROL AREA (TCA) & WASN'T IN RADIO CONTACT WITH ATC. LAX TRACON
WASN'T EQUIPPED WITH AN AUTO CONFLICT ALERT SYS & THE ANALOG
BEACON RESPONSE FM N4891F'S X-PONDER WASN'T DISPLAYED DUE TO EQUIP
CONFIGURATION. N4891F'S PSN WAS DISPLAYED BY AN ALPHANUMERIC
TRIANGLE, BUT THE PRIMARY TARGET WASN'T DISPLAYED DUE TO AN
ATMOSPHERIC INVERSION

What I infer from this is, that the controller's display wasn't
configured to display the Piper's transponder at the time of the
collision. That would imply that the controller reconfigured his
display between the time he noted the Piper squawking 1200 and the
time of the MAC.

As there is no mention of the Piper's altitude, I would assume it
wasn't squawking Mode C. That would be required for proper TCAS
operation if I'm not mistaken. So, I agree with your conclusion, but
for other reasons.


IIRC it is (or was) common practice to eliminate "1200s" from displays in
high traffic areas for clarity purposes. I don't know if the Piper was
equipped with Mode C at the time or not.
My statement about the X-Ponder being in stand-by was distant memory of a
report that I can't cite where from. Maybe a news report? I dunno, I wish I
could remember.
I can only agree with your reasoning on the issue.

Marty