US Airways Talks with Pilots Collapse  WASHINGTON (Reuters) - Negotiations between US Airways  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=UAIR.O target=/stocks/quickinfo/fullquote"&gt;UAIR.O&lt;/A&gt; and its pilots union over a new round of steep  concessions collapsed on Monday, heightening pressure on the  carrier as it tries to avert insolvency.