Re: India:747/Tu154 collision +TCAS

Date:         13 Nov 96 02:41:21 
From:         s_odle@earthlink.net (Scott Odle)
Organization: Earthlink Network, Inc.
References:   1 2
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In article <airliners.1996.2387@ohare.Chicago.COM>, kls@ohare.Chicago.COM
says...

>They may only use select aircraft for service to the US, so only some
>of their aircraft would need TCAS and perhaps other special equipment
>for US operations.  (I have no idea if they actually do this or not.)
>Even if TCAS-equipped, it's possible they weren't using it if they
>weren't required to do so, perhaps if it was inoperative.

The only thing to add is that even if the second aircraft were a TU154,
since it is a cargo aircraft (as reported by the news media)it would not
be required to have TCAS in the U.S.

>I *think* the other aircraft need only have a (mode C?) transponder.

Correct. While TCAS can display Mode A targets it does not no their altitude
and assumes co-altitude.  For full functionality the second aircraft should
have at least a working Mode C or Mode S.