Ausflyer,
There are plenty of non Americans flying in the US. All without, exception, will have, at minimum, a green card. You will need that and, IMHO, a college degree. Maybe UAL mentions collage as preferred but, rest assured, it is a requirement for those of us who do not rate special access to the majors. If you are single I would strongly suggest you find a nice American girl to fall in love (with you). This will be your easiest way to the green card. My suggestion, attend a 4 year university in the USA working on both the degree and green card at the same time. After that, follow the advice given all over the place on this site for getting the right quals to get your United job.