In which year did the first powered flight by a heavier-than-air aircraft occur?

The first powered flight by a heavier-than-air aircraft occurred in 1903 when the Wright brothers, Orville and Wilbur, successfully flew their aircraft known as the Wright Flyer. This event, on December 17, 1903, marked a significant milestone in aviation history as it demonstrated controlled, sustained flight with a powered engine and a pilot on board.

The significance of this achievement cannot be overstated; it laid the groundwork for modern aviation engineering and inspired subsequent developments in aircraft design and technology. The Wright brothers' success was due to their innovative approach to flight control, aerodynamics, and their pioneering use of a lightweight engine.

In contrast to the other years provided, 1891 is significant for the early experiments in gliding but does not represent a powered flight. The years 1914 and 1927 pertain to advancements in aviation technology and milestones like the use of aircraft in World War I and Charles Lindbergh's transatlantic flight, respectively, but they do not pertain to the achievement of the first powered flight by a heavier-than-air aircraft.