(Reuters) - Mesa Air Group ( MESA ) will sell 18 Embraer ( ERJ ) aircraft to United Airlines for about $229.1 million and use the proceeds to cut debt, the regional airline operator said on Tuesday.

Shares of Mesa ( MESA ), the parent company of Mesa Airlines, rose more than 10% before the bell.

Most of the aircraft of the Phoenix, Arizona-based company are operated under an agreement with United, where they fly under the United Express brand.

Mesa ( MESA ) completed the sale of eight of the 18 aircraft on Dec. 31 and expects to close the rest by the end of this month.

The company expects to use $142.4 million of the gross proceeds from the sale to pay off associated debt, Mesa ( MESA ) said in a regulatory filing.

Mesa ( MESA ) also said it had entered into a separate deal with a third party on Dec. 24 to sell 15 used Bombardier CRJ-900 airframes for about $19 million.

The company intends to use the cash from that transaction to pay down its loan with the U.S. Treasury.