Flight nursing requirements

For a new foreign RN, 3 years non-ER experience, taken CGFNS and NCLEX, ACLS, NRP, PALS, TNCC, PHTLS and ALSO. If I would like to work for flight nurse in USA, should l start my work in one hospital which there are flight programme? Or I should start my work in one hospital with busy ER first to get more experience and then work for another hospital which there are flight programme?

If the requirement of a flight nurse needs to have ER/Critical Care experience, is there any training(course) or exam I should take before I work in these units?

Thank you very much!