 Time to Hurn was 17 hours 40 minutes including stops, or 20 hours 45 minutes to Lisbon.A Boeing 314 flying boat flew LaGuardia to Lisbon once every two weeks in 29 hours 30 minutes; flying boat flights ended shortly thereafter.TWA's transatlantic challenge – the impending introduction of its faster, pressurized Lockheed Constellations – resulted in Pan Am ordering its own Constellation fleet at $750,000 apiece.