Re: TCAS incident at PDX

From: (Kevin Au)
Organization: University of California, Berkeley
Date:         26 Mar 94 12:20:01 PST
References:   1
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This sounds like a familiar problem.  AW&ST had been talking about
problems with TCAS in situations where one aircraft is descending and
another is ascending.  The problem is that TCAS senses the approaching
aircraft, but does not know that it is about level off.  It projects the
expected trajectories as if they were to continue their climbs or descents
and issues an RA that may tell one plane to climb steeper or another plane
to descend steeper.  This seems to be what had happened again at PDX.