Heyas,
I think the question the OP was asking was a little different than the answers he got.
Everything I've read says that it is virtually impossible these days to even get a green card, let alone an immigration visa (way different than a temporary one) unless you have a lot of horsepower with who you work for or a relative that will sponsor you.
And when I say horsepower with your employer, that means you are a PhD, MD or have some other kind of highly specific or technical skill. So highly specific that they can't find it locally. Or you have a TON of money. Like millions (actors/actresses/etc). In either case, these people spend a TON of cash greasing the skids of the immigration process.
Now none of these things apply in any way to the airline industry. You think some regional, or even a major for that matter, is going to pay some immigration attorney 100k to push a visa application for a new hire? So how to people still find their way into the business?
Well, legal immigration. That accounts for a TINY minority.
Sponsorship of a blood relative. That accounts for a bit more.
But the simple answer is marrage. Lots and lots of it. And if you don't think "targeted" marrage doesn't account for a TON of how people get green cards, then you are hopelessly naive.
When I was a CFI, we had more than a few Euro types come over on the "education" visa. The one where you could "work" in your field of study for up to two years.
As the visa period came to a close, one offered cash money for marrage. "$5000, and 3 years and anything goes".
Another, who planned WAY ahead, left their spouse and filed for divorce the day after the 3 year window was over.
Think it was just men working the action? The above two cases were perpetrated by women. My buddy who had his wife leave at the 3 year mark was devistated. He had NO idea that was what she was after. Silly him, he thought it was love.
That was nearly 20 years ago. They may have tightened down the rules since then, but I doubt it. A friend had her husband leave after he got his citizenship, and that was just a few years ago. She also had no idea.
My guess this accounts for a big part of what you see in the airline business. But its "legal immigration". Most of it may even because people are in love and are committed to each other. I will leave it to your personal inclinations as to what the percentages are.
But the laws have changed. Many universities are having a severe time finding graduate students for the sciences (math, engineering, computer science, natural sciences, etc) because the laws and the vetting process governing those people has become quite strict. Many universities also work on government projects require background checks that these people simply cannot complete. As a result, the demand for US Citizens in graduate programs has skyrocketed. If you want to go to grad school, and you are a US Citizen, there are some amazing deals out there. Places will bend over backwards for you.
Nu