Re: India:747/Tu154 collision +TCAS

Date:         20 Nov 96 05:48:30 
From:         Bill Chivers <>
Organization: Chivers Consultants
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In article <airliners.1996.2429@ohare.Chicago.COM>, Scott Odle
>There will be no TCAS III.  For whatever reason it will be designated TCAS IV.

If I Remember Correctly:

TCAS III - Intention was to provide horizontal avoidance, as well as the
vertical methods used in TCAS II. Abandoned due to problems with
insufficient aerial resolution in the horizontal plane, such that
position of the conflicting traffic could not be determined accurately
enough to figure out the avoid. Therefore no TCAS III.

TCAS IV - To use GPS position info, sent via Mode S to the conflicting
traffic. Exact position information will allow horizontal avoids to be

Bill Chivers
'my other signature file has something funny at the bottom of it'