Ord - ogg - koa
This former flight number 3 usually only runs on weekends during peak time. For example, it ran last weekend due to the beginning of spring break. It also runs during the Christmas and New Year holidays.
It does a triangle by flying from Chicago O'Hare to Kahului-Maui to Kailua-Kona back to Chicago O'Hare. United drops off and picks up passengers on one of these two islands.