The pilots union at Delta Air Lines has elected a new chairman, a surprise change in leadership coming on the heels of the approval of a new labor contract with pay raises.

The leadership committee of the Air Line Pilots Association at Delta voted to elect Bill Bartels as chairman, with a close 10-9 vote.

"Many threats remain on the horizon, both to our flying jobs and working conditions," Bartels said in a written statement.

Bartels starts his two-year term Jan. 1, replacing John Malone in the Delta pilots union chairman slot.

Malone was elected to the position in September 2015. He filled the spot vacated by the resignation of his predecessor Mike Donatelli, following the first-ever defeat of a proposed labor deal in voting by Delta pilots. It was Malone's second time stepping into the chairman position, after leading the Delta pilots union from 2003 to 2005.

Malone sought big pay raises in new contract talks this year, opening negotiations with a proposal for nearly 40 percent compounded pay raise over three years.

The final deal approved last week included compounded raises of 30.2 percent over four years. Of the Delta pilots casting ballots, 82 percent voted in favor.

The election of Bartels as chairman brings to the helm a longtime union officer who was a pilot at highly-unionized Northwest Airlines before the Delta-Northwest merger in 2008.

More recently, Bartels has been chairman of the Delta pilot union's local council in Detroit.