This record setting 1929 Travel Air S6000B paved the way for modern in-flight refueling by establishing a 13-day endurance records in September 1930. This lovely old lady, no dowager queen, is still flown daily from Homer Alaska by Kachemak Bay Air Service, a certified air carrier.
This floatplane paved the way back when there were round engines, and rag wings, and shiny varnish on golden wood ribs. With wicker seats, mahogany framed roll down windows, fresh flowes in a crystal vase, a tiled lavatory, and broadcloth seat covers it personified luxury aloft. Fledgling Delta and Braniff flew them and they were touted as the "Limousine of the Air."
Phillips Petroleum even sponsored this aircraft and a crew that stayed up for 13 days without a landing or, for that matter, a bath. A hose was lowered from another aircraft to transfer fuel and, clinging to a makeshift catwalk, the crew changed spark plugs inches from the spinning propeller, thousands of feet from the ground.
See http://www.alaskaseaplanes.com/NC9084.html for more information on this historic aircraft and her equally renown pilot, an Alaskan hero.