Nicolaus Copernicus 1st recorded astronomical observation.
The first American air casualty in World War I is Capt. James E. Miller who loses his life in a French Spad while flying a practice patrol across the German lines.
U.S. Navy Lt. Comdr. E. O. McDonnell makes the first successful flight from a gun turret platform on a U.S. navy battleship. The USS Texas is anchored in Guantanamo Bay, Cuba for the test.
The English aviatrix Lady Mary Bailey takes off from Croydon on what becomes the first round-trip flight between London and Cape Town, South Africa flown by a woman. She arrives back in England on May 12.
A new parachute descent record of 35,450ft. is achieved by the French parachutist James Williams when he jumps from the cockpit of an ANF Les Mureaux 113 high-wing monoplane after taking off from the airfield at Chartres. Dropping to a height above the ground of 650 ft. in 2 minutes 50 seconds before opening his parachute, Williams easily achieves a world free-fall record.
The Great Tokyo Air Raid, an overnight incendiary bombing raid by B-29 Superfortresses on Tokyo, is one of the most destructive air raids in history. It creates a firestorm which destroys 41 square kilometers (16 square miles) of the city, killing an estimated 88,000 to 125,000 people, injuring at least 41,000 and perhaps as many as a million people, and leaving probably a million people homeless.
First flight of the Avro Shackleton prototype VW126.
1st known radar contact is made with Venus.
1st animal returned from space, dog named Blackie aboard Sputnik 9.
Vega 2, USSR Venus/Comet Halley Probe made its comet flyby.
NASA announces searchers found remains of Challenger astronauts.
First flight of the Yakovlev Yak-141.
U.S. 70th manned space mission STS-39 (Discovery 12) launches into orbit.
Colonel John (Richard) Boyd passes away at West palm Beach, FL. He was dubbed "Forty Second Boyd" for his standing bet as an instructor pilot that beginning from a position of disadvantage, he could defeat any opposing pilot in air combat maneuvering in less than forty seconds. A man with a self-admitted sub-100 IQ, he was a genius.
The Space Shuttle Discovery, first of the space shuttles to be retired, glides to a landing to end its 39th and final mission - the most by any space shuttle.