Before World War II, overseas and cross-country presidential travel was rare. The lack of wireless telecommunication and available modes of transportation made long-distance travel impractical, as it took too much time and isolated the president from events in Washington, D. C. Railroads were a safer and more reliable option if the president needed to travel to distant states. By the late 1930s, with the arrival of aircraft such as the Douglas DC-3, increasing numbers of the U. S. public saw passenger air travel as a reasonable mode of transportation. All-metal aircraft, more reliable engines, and new radio aids to navigation had made commercial airline travel safer and more convenient. Life insurance companies even began to offer airline pilots insurance policies, albeit at extravagant rates, and many commercial travelers and government officials began using the airlines in preference to rail travel, especially for longer trips.