Alaska Air Group has reported a 10.9% rise in traffic in May.
The group's capacity rose 8.3%, while the load factor increased 2 percentage points to 86%. Its passenger numbers grew 5.4% year-on-year to 2.16 million.
Consolidated results include flights operated by Alaska and those under capacity purchase agreements, including Horizon, SkyWest and PenAir.
Alaska Airlines reported an 11.2% increase in traffic year-on-year in May while passenger numbers increased 5.6% to 1.57 million.
The airline's capacity grew 8.5% in May, while the load factor increased 2.2 percentage points to 86.9%.
Horizon Air's traffic declined 4.6%, while capacity fell 3.1% in May.
The airline's load factor fell 1.1 percentage points to 76.3%. Horizon carried 549,000 passengers, up 0.4% compared with the same month last year.