I'm from China and I am studying AE in University of Illinois in the US. I would like to work in the US after graduate. It's clear that an American citizenship is necessary to find a job in some companies on designing and manufacturing, like Boeing and Locked Martin. I want to know whether I can work in airlines, for example, Delta, Northwest, United, and some companies only focus on civil use, like Cessna Cirrus,as an engineer without the American citizenship. I look this up on their websites, but they don't say anything about citizenship. Does that mean those companies do not require American citizenship, or its just a tradition, so, they simply don't mention it? Thank you!