Did a monk of the 11th century accomplish the first manned flight? There is reason to believe so.
In the Gesta Regum Anglorum [Deeds of the English Kings] of William of Malmesbury, we read of a monk named Eilmer in Malmesbury Abbey who launched himself from the Abbey's tower with a set of home-made wings. According to the story, he glided more than a furlong (a furlong is 220 yards, or just over 200 meters). Then, suddenly realizing how precarious his position was, he panicked, lost control, and crashed, breaking both legs. He had extreme difficulty walking for the rest of his life.
How likely is this story to be true? Let's first consider what we might call "incidental" evidence. William is not just reporting a legend: although he lived after Eilmer, he was in the same Abbey, and very likely got the story from elders who knew Eilmer and had witnessed the experiment first-hand.
William also records a curious detail: that Eilmer ever after claimed his failure was due to not constructing a tail for his device. This suggests that Eilmer really did study birds in flight, and realized that a tail is also important to steer and brake for landing. Unfortunately for the history of manned flight, the abbot forbade him or anyone from repeating the crippling experience.
But was such a flight possible? Several historians have weighed in, and even the United States Air Force is willing to accept it. The conditions that make it believable are as follows:
The Abbey was situated at a cliff edge over the Avon River that would have created strong updrafts. Eilmer would have seen how jackdaws use the strong updraft to glide and soar without the need to flap. The tower would have been about 80 feet high, giving him additional altitude for catching an updraft. If Eilmer were a small man, calculations suggest that a light and strong frame of willow or ash, covered with parchment or light cloth, would only need an area of 100 square feet to support his weight. William says the wings were attached to Eilmer's hands as well as feet—this supports the notion that they covered a larger area than just wings attached to arms.
Local legend says his landing spot is an area now called "Oliver's Lane." (Ralph Higden's Polychronicon—mentioned here—erroneously referred to Eilmer as Oliver, and the name stuck.) Given the constant wind conditions and the distance he is supposed to have flown, Oliver's Lane is precisely where modern calculations based on wind currents place his likely landing spot. The gliding flight would have lasted about 15 seconds.
He lived a long time afterward, becoming known for scholarship. His writing on astronomy existed and was well-known into the 16th century, but has been lost since. Also lost to history is the tavern "The Flying Monk" in Malmesbury, which has since been replaced by a shopping center.