discrimination
Sorry guys, but under the interpetations of discrimination laws currently in use by US courts, it is not discrimination to use citizenship as a basis for employment. My current employer has been sued twice that I know of, for this very issue. Both times he won due to the government contracts that he holds that require US citizens. Being an international company, we do have many non-US citizens working for us, but not in certain job areas.
The biggest issue is the 12.5 rule the TSA has imposed on all operators of aircraft 12,500 pounds and above. It has taken 6 months or more to complete the requirements of the rule. I don't know of any company that is willing to deal with that.
And Cochise, yes there are more than enough US citizens available to fill the available pilot slots.