CFR > Title 41 - Public Contracts and Property Management > SUBTITLE F—Federal Travel Regulation System > CHAPTER 301—TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES (parts 301-1 to 301-76) > SUBCHAPTER B—ALLOWABLE TRAVEL EXPENSES (parts 301-10 to 301-31) > PART 301-10—TRANSPORTATION EXPENSES > SUBPART B—Common Carrier Transportation (§301-10.100 to §301-10.190) > 301-10.137—What exceptions to the Fly America Act requirements apply when I travel solely outside the United States, and a U.S. flag air carrier provides service between my origin and my destin

301-10.137—What exceptions to the Fly America Act requirements apply when I travel solely outside the United States, and a U.S. flag air carrier provides service between my origin and my destin

You must always use a U.S. flag carrier for such travel, unless, when compared to using a foreign air carrier, such use would:
(a) Increase the number of aircraft changes you must make en route by 2 or more; or
(b) Extend your travel time by 6 hours or more; or
(c) Require a connecting time of 4 hours or more at an overseas interchange point.