USAir Asks Court for 23 Pct Union Pay Cut  NEW YORK (Reuters) - US Airways Group Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=UAIRQ.PK target=/stocks/quickinfo/fullquote"&gt;UAIRQ.PK&lt;/A&gt; will  ask a bankruptcy court on Friday to impose emergency pay cuts  of 23 percent on unionized workers, in an effort to help the  No. 7 U.S. airline stay alive.