Phoenix-based Mesa Airlines is deepening its partnership with United Airlines at the same time the regional carrier is running up against problems in its relationship with American Airlines.

The contract for 42 United-owned Embraer E175s in Mesa’s United Express fleet will be extended five years through 2024, with rights to extend through 2027, the airlines announced Dec. 3. The 18 Mesa-owned E175s in the United Express fleet will be contracted through 2028.

Mesa also said it will add 20 new 70-seat E175 LL aircraft to its United capacity purchase agreement (CPA), with deliveries set to run from May through December 2020. The E175s, which will be owned and financed by Mesa, will replace the carrier’s 20 remaining Bombardier CRJ-700s in its United Express fleet, which in turn will be leased out to another of United’s regional affiliates for seven years.

The transactions will leave Mesa with a United Express fleet comprising 80 E175s with an average age of 3.7 years. Mesa said in a statement it “expects the shift to a single fleet type to improve utilization of crew and maintenance resources across its United Express system.”

“We are pleased to increase the number of Embraer aircraft operating under our partnership with United to 80, making Mesa the largest E175 operator under the United Express banner,” Mesa Air Group CEO Jonathan Ornstein said.

The transactions “are a positive for Mesa,” Cowen & Co. analyst Helane Becker said, adding that while negotiations with United have been slow-moving, a CPA extension that provides growth for Mesa “should be viewed favorably.”

Meanwhile, Mesa announced separately it had not met certain performance metrics for American Airlines in the most recent period, which allows American to remove two aircraft from their CPA. While American opted to defer its right to do so, it has confirmed it will remove one of two previously deferred aircraft, effective Jan. 2, 2020. An American spokesman declined to comment.

Becker observed that Mesa continues to have difficulties with operational reliability in its American operations, but said the airline “appears to be giving Mesa the benefit of the doubt by not removing aircraft quicker,” which she attributed to slower-than-expected domestic growth at American resulting from the Boeing 737 MAX grounding.

“Mesa needs to start executing their operational targets or could potentially lose additional aircraft going forward,” Becker said.

Ben Goldstein, Ben.Goldstein@aviationweek.com