Darwin International Airport / RAAF Darwin to Baltimore/Washington International Thurgood Marshall Airport
Approx. 15991 km - about 17h 51m in the air and 19h 09m total from gate to gate, at an average speed around 896 km/h.
Real-world flights on routes this long almost always include at least one stop. Use this nonstop estimate as a guide, and allow extra time for connections and layovers when planning your trip.