Category 1 is always the greatest level of hazard (that is, it is the most hazardous within that class). If Category 1 is further divided, Category 1A within the same hazard class is a greater hazard than category 1B. Category 2 within the same hazard class is more hazardous than category 3, and so on.
Correction: An earlier version of this story incorrectly stated that Charles Nungesser and Francois FranÃ§ois coli would have been the first pilots to make a nonstop transatlantic. Flight a pair Of british pilots made such a flight in. 1919
But even before the leaders sat down to talk, FDR made history. His trip across the Atlantic, in a Boeing 314 flying boat, was the first time a sitting U.S. president flew on an airplane. Nobody was more impressed than his pilots.