...depends
It depends on the stage of the approach / departure. Certain versions of TCAS are inhibited until circa 1,000RA on climb, and below 1,000RA on descent (This is from memory - I could be wrong) So no, you cannot rely on TCAS to sort this out.
Edited to add: As mentioned below, otherwise at busy airports it would be a nightmare, plus that close to the ground you would probably question a TCAS demanding a fly down...
Last edited by dwshimoda; 2nd Aug 2012 at 23:56.