41 C.F.R. § 102-117.45 – Exceptions.

(a) Fly-America Act. Shippers may use a foreign-flag carrier only when:
1. (1) No U.S. flag carrier service is available;
2. (2) Emergency or mission-critical time constraints require foreign service;
3. (3) A bilateral/multilateral air transport agreement permits it;
4. (4) Transportation costs are fully reimbursed by a third party; or
5. (5) Using a U.S. carrier would create an unreasonable safety risk, supported by appropriate agency documentation.
(b) Detailed Fly America exemptions are published separately by GSA. Refer to GSA's Transportation Policy web page guidance for the latest criteria. See https://www.gsa.gov/policy-regulations/policy/transportation-management-policy.
(c) Maritime Administration (MARAD). See https://www.maritime.dot.gov/ports/cargo-preference/cargo-preference for exceptions and determinations of non-availability.