It's not that a single airline was under Chapter 11 for over a decade. But over a long period of time they have filed and been protected by Chapter 11 which is an absolute no no outside North America.
Continental Airlines: SEP 1983 to JUN 1986
US Airways: AUG 2002 to MAR 2003 and SEP 2004 to SEP 2005
Delta Air Lines: SEP 2004 to SEP 2005
American Airlines NOW 2011 to DEC 2013