Regarding Greenways Academy and accreditation: It is also accredited by the NorthCentral Association and that should be acceptable to most everyone. CITA, however, is also a legitimate accreditor (because it is a conglomerate of regional accreditors and others).
I think it is good that Greenways is positive about the IATA course. Please let us know if other schools are as well. I learn so much from the real-world experiences of students.
http://www.bestonlinehighschools.com/directory/property/online-high-schools/greenways-academy/As to the SAT, if you are planning on going to college in the U.S., then taking the SAT would be helpful. There should be a place in Qatar to do that, I believe. Depending on your citizenship, they might require you to take the TOEFL as well (which is rather humorous given your command of the language, but sometimes it's about being able to put a checkmark in a box).
Other questions?
Tom Nixon
