January 25 - 2nd Lt Carl Mather is killed in an aircraft collision.
February 5 - 2nd Lt Stephen W. Thompson achieves the first aerial victory by the U.S. military.
February 8 - Lafayette Escadrille, the US volunteer squadron serving in the French Army is transferred to the US Army and redesignated the 103rd Aero Squadron.
March 6 - the Finnish Air Force is founded
March 6 - the first ever successful flight of a powered unmanned heavier-than-air craft, the Curtiss-Sperry Flying Bomb, which was the precursor to modern UAVs.
March 11 - the first regular international airmail service begins, with Hansa-Brandenburg C.I aircraft linking Vienna, Lviv, Proskurov, and Kiev.
March 18 - the first Norwegian airline, Det Norske Luftfartrederi, is founded
March 21 - Germany launches Operation Michael, marking the beginning of the Spring Offensive. In the initial attack against the British front west of St Quentin, the German Army Air Service has 1,680 aircraft to the Royal Flying Corps' 579.
March 24 - Captain J.L. Trollope of No. 43 Squadron RFC shoots down six German aircraft in a day.
March 25 - Ensign John McNamara makes the first US Navy attack on a submarine.
March 30 - Alan Jerrard VC, British ace (7 victories) is shot down by Benno Fiala von Fernbrugg and taken captive
April 1 - the Royal Flying Corps and Royal Naval Air Service combine to form the Royal Air Force. The Women's Royal Air Force is formed at the same time.
April 12 - the final Zeppelin raid on England is carried out.
April 12 - Captain H.W. Woollett of No. 43 Squadron RAF scores six victories in two sorties, including five Albatros D.Vs.
April 21 - Manfred von Richthofen, a living legend called the "Red Baron" and "ace of aces" is shot down and killed. By the time of his death, he had claimed 80 victories. Credit for his kill is given to Canadian Cpt Roy Brown, but this is disputed by others who claim that he was killed by ground fire from Australian troops.
April 23 - Lt Paul Baer shoots down his fifth aircraft, becoming the first ace of the American Expeditionary Force
April 25 - Belgium's top-scoring ace, Willy Coppens, claims his first victory.
May 15 - The first regular US airmail service commences, between New York and Washington, DC. The first flight is made by Lt Geoffrey Boyle in a Curtiss JN-4H.
May 19 - Raoul Lufbery, commander of the 94th (Hat in the Ring) Aero Squadron and second highest scoring American ace with 17 victories, is killed in air combat.
May 20 - German bombs fall on London for the last time in World War I.
May 24 - Josef Kiss, Austro-Hungarian 5th highest scoring ace, is shot down in combat. He had scored 19 victories.
A detachment of US bomber pilots is stationed in Italy to strike at Austria.
June 19 - Italy's highest-scoring ace, Maggiore Francesco Baracca is killed by Austrian ground fire. He had claimed 34 victories.
June 24 - the first scheduled Canadian airmail flight is made, between Montreal and Toronto.
June 24 - The RAF deploys its new 1,650 lb (748 kg) bomb for the first time. One is dropped on Middelkerke, Belgium by a Handley Page O/400 of No. 216 Squadron RAF.
July 9 - British ace James McCudden is killed when his aircraft crashes on take-off.
July 26 - Maj Edward Mannock, Britain's highest scoring ace of the war, is shot down by German ground fire. He had scored 73 victories.
July 31 - Lt Frank Linke-Crawford, Austrian 4th highest scoring ace, is shot down in combat. He had scored 27 victories.
August 11 - Flt Sub-Lt Stuart Culley shoots down Zeppelin L 53 after taking off from a barge towed behind HMS Redoubt
August 11 - the first use of a parachute from a combat aircraft when a German pilot escapes his burning Pfalz DIII after being attacked by a pilot from No. 19 Squadron RAF.
Known as Black September, during the month the Allies lose 560 aircraft, of which 87 are American.
September 12 - 627 French and 611 US fighters are brought together for the Battle of Saint-Mihiel. At the time, it is the largest force of aircraft assembled for a single operation.
September 24 - Lt David Ingalls claims his fifth victory, to become the only US Navy ace of World War I.
October 5 - French famous pilot Lt Roland Garros is shot down and killed in combat.
October 14 - Baron Willy Coppens, highest scoring Belgian ace, is heavily wounded, ending his combat career. He had scored 37 victories, 34 of which were observation balloons.
October 29 - The Danish airline Det Danske Luftfartselskab, the oldest airline that still exists, is founded
November 11 - the end of the First World War. The RAF suffered 16,623 casualties, while the German Air Service suffered in excess of 15,000.
December 12 - Cpt R.M. Smith, Brig Gen A.E. Borton and Maj Gen W. Salmond set out in a Handley Page O/400 from Heliopolis to Karachi, to survey a route for airmail to India.
December 13 - Maj A.S.C. MacLaren and Cpt Robert Halley set out on the first England-India flight, in a Handley Page V/1500
March 4 - Airco DH.10
March 6 - Curtiss-Sperry Flying Bomb
March 10 - Junkers D.I
Handley Page V/1500
June 6 - Fairey III
August 7 - Blériot-SPAD S.XX
August 17 - Martin MB-1
August 21 - Nieuport-Delage Ni-D 29
October 2 - Kettering Bug