Preferring to fly UA is not a reason to shun Kayak and other exterior search engines. I find the UA engine fails to display up to half the options available (UA and partners), UA and non-UA, one-stop and two-stop. Kayak, Expedia, and others will expose better and often cheaper itineraries. But I don't know if the lame UA engine is deliberately engineered to limit customers' options or just a mess.