* Delta, AMR raise fares on domestic routes
* Industrywide fare hike is sixth this year
* Arca airline index down 1.5 pct
CHICAGO, Oct 30 (Reuters) - Delta Air Lines (DAL.N) and AMR Corp's AMR.N American Airlines raised fares by $6 to $10 on domestic round trips on Friday, completing the sixth industrywide increase of 2009, a top airfare expert said.
The moves reflect new pricing power by U.S. airlines as they claw their way out of an economic downturn that eroded travel demand and forced them to slash capacity. Major U.S. airlines initiated another broad-based domestic fare hike last week.
The most recent fare hikes began on Thursday with one launched by AirTran Airways, a unit of AirTran Holdings AAI.N, said Rick Seaney, chief executive of Farecompare.com.
"I've never seen one matched this quickly that failed," Seaney said.
Major carriers followed AirTran's lead on Thursday, and Delta and AMR "filled in the gaps" on Friday morning, Seaney said.
The Arca airline index .XAL was down 1.5 percent on Friday. Delta shares fell 12 cents, or 1.6 percent, to $7.24 on the New York Stock Exchange, while AMR was down 14 cents, or 2.5 percent, at $5.50. (Reporting by Kyle Peterson; Editing by Lisa Von Ahn)