This part applies to all the flights of a certificated or commuter air carrier if the carrier operates scheduled passenger service or public charter service using any aircraft originally designed to have a passenger capacity of 30 or more seats, and to all flights to and from the U.S. of a foreign air carrier if the carrier operates scheduled passenger service or public charter service to and from the U.S. using any aircraft originally designed to have a passenger capacity of 30 or more seats, except as otherwise provided in this part. This part does not apply to foreign air carrier charters that operate to and from the United States if no new passengers are picked up in the United States. Section 259.4 does not apply to a flight that diverts to the United States when the flight is operated by a foreign air carrier and scheduled to operate between two foreign points.