World War I
Manfred von Richthofen
, better known as the "Red Baron". He scored the most officially accepted kills in World War I and is arguably the most famous flying ace of all time.
World War I introduced the systematic use of true single-seat fighter aircraft, with enough speed and agility to catch and maintain contact with targets in the air, coupled with armament sufficiently powerful to destroy the targets. Aerial combat became a prominent feature with the
Fokker Scourge, in the last half of 1915. This was also the beginning of a long-standing trend in warfare, showing statistically that approximately five percent of combat pilots account for the majority of air-to-air victories.
Use of the term "ace" to describe these pilots began in
World War I, when
French newspapers described
Adolphe Pégoud, as l'As (French for "
Ace") after he became the first pilot to down five
German aircraft. The British initially used the term "star-turns" (a show business term), while the Germans described their elite fighter pilots as Überkanonen (which roughly translates to "top gun").
The successes of such German ace pilots as
Max Immelmann and
Oswald Boelcke were much publicised for the benefit of civilian morale, and the
Pour le Mérite, Prussia’s highest award for gallantry, became part of the uniform of a leading German ace. In the Luftstreitkräfte the Pour le Mérite was nicknamed Der blaue Max/The Blue Max, after Max Immelmann, who was the first fighter pilot to receive this award. Initially, German aviators had to destroy eight
Allied aircraft to receive this medal.
 As the war progressed, the qualifications for Pour le Mérite were raised,
 but successful German fighter pilots continued to be hailed as national heroes for the remainder of the war.
German fighter squadrons usually fought well within German lines, it was practicable to establish and maintain very strict guidelines for the official recognition of victory claims by German pilots. Shared victories were either credited to one of the pilots concerned or to the unit as a whole – the destruction of the aircraft had to be physically confirmed by locating its wreckage, or an independent witness to the destruction had to be found. Victories were also counted for aircraft forced down within German lines, as this usually resulted in the death or capture of the enemy aircrew.
Allied fighter pilots fought mostly in German-held airspace
 and were often not in a position to confirm that an apparently destroyed enemy aircraft had in fact crashed, so these victories were frequently claimed as "driven down", "forced to land", or "out of control" (called "probables" in later wars). These victories were usually included in a pilot's totals and in citations for decorations.
The British high command considered praise of fighter pilots to be detrimental to equally brave bomber and reconnaissance aircrew – so that the British air services did not publish official statistics on the successes of individuals. Nonetheless some pilots did become famous through press coverage,
 making the British system for the recognition of successful fighter pilots much more informal and somewhat inconsistent. One pilot,
Arthur Gould Lee, described his own score in a letter to his wife as "Eleven, five by me solo — the rest shared", adding that he was "miles from being an ace".
 This shows that his
No. 46 Squadron RAF counted shared kills, but separately from "solo" ones—one of a number of factors that seems to have varied from unit to unit. Also evident is that Lee considered a higher figure than five kills to be necessary for "ace" status. Aviation historians credit him as an ace with two enemy aircraft destroyed and five driven down out of control, for a total of seven victories.
, Britain's first famous flying ace. He was killed in 1917, aged 20.
Other Allied countries, such as France and Italy, fell somewhere in between the very strict German approach and the relatively casual British one. They usually demanded independent witnessing of the destruction of an aircraft, making confirmation of victories scored in enemy territory very difficult.
 The Belgian crediting system sometimes included "out of control" to be counted as a victory.
United States Army Air Service adopted French standards for evaluating victories, with two exceptions – during the summer of 1918, while flying under operational control of the British, the
17th Aero Squadron and the 148th Aero Squadron used British standards.
 American newsmen, in their correspondence to their papers, decided that five victories were the minimum needed to become an ace.
While "ace" status was generally won only by fighter pilots, bomber and reconnaissance crews on both sides also destroyed some enemy aircraft, typically in defending themselves from attack. The most notable example of a non-pilot ace in World War I is
Charles George Gass with 39 accredited aerial victories.
Between the world wars
There were two theaters of war that produced flying aces between the two world wars. They were the
Spanish Civil War and the
Second Sino-Japanese War.
Joaquín García Morato scored 40 victories for the Nationalists during the Spanish Civil War. Part of the outside intervention in the war was the supply of "volunteer" foreign pilots to both sides. Russian and American aces joined the Republican air force, while the Nationalists included Germans and Italians.
Soviet Volunteer Group began operations in the Second Sino-Japanese War as early as December 2, 1937, resulting in 28 Soviet aces.
Flying Tigers were American military pilots recruited
sub rosa to aid the
Chinese Nationalists. They spent the summer and autumn of 1941 in transit to China, and did not begin flying combat missions until December 20, 1941.
World War II
World War II many air forces adopted the British practice of crediting fractional shares of aerial victories, resulting in fractions or decimal scores, such as 11½ or 26.83. Some U.S. commands also credited aircraft destroyed on the ground as equal to aerial victories. The Soviets distinguished between solo and group kills, as did the Japanese, though the
Imperial Japanese Navy stopped crediting individual victories (in favor of squadron tallies) in 1943.
of the Soviet Air Force, one of only two female flying aces in history.
Soviet Air Forces has the top Allied pilots in terms of aerial victories,
Ivan Kozhedub credited with 66 victories and
Alexander Pokryshkin scored 65 victories. It also claimed the only female aces of the war:
Lydia Litvyak scored 12 victories and
Yekaterina Budanova achieved 11.
 Fighting on different sides, the French pilot
Pierre Le Gloan had the unusual distinction of shooting down four German, seven Italian and seven British aircraft, the latter while he was flying for
Vichy France in
Luftwaffe continued the tradition of "one pilot, one kill", and now referred to top scorers as Experten.
[N 1] During the war, and for some years after, the very high victory totals of some Experten were considered by many historians to be coloured by grandiose
Nazi propaganda. In spite of this, there are 107 German pilots with more than 100 kills.
A number of factors probably contributed to the very high totals of the top German aces. For a limited period (especially during
Operation Barbarossa), many Axis victories were over obsolescent aircraft and either poorly trained or inexperienced Allied pilots.
 In addition, Luftwaffe pilots generally flew many more individual
sorties (sometimes well over 1000) than their Allied counterparts. Moreover, they often kept flying combat missions until they were captured, incapacitated, or killed, while successful Allied pilots were usually either promoted to positions involving less combat flying or routinely rotated back to training bases to pass their valuable combat knowledge to younger pilots. An imbalance in the number of targets available also contributed to the apparently lower numbers on the Allied side, since the
number of operational Luftwaffe fighters was normally well below 1,500, with the total aircraft number never exceeding 5,000, and
the total aircraft production of the Allies being nearly triple that of the other side. A difference in tactics might have been a factor as well;
Erich Hartmann, for example, stated "See if there is a straggler or an uncertain pilot among the enemy... Shoot him down.",
 which would have been an efficient and relatively low-risk way of increasing the number of kills. At the same time, the Soviet 1943 "Instruction For Air Combat" stated that the first priority must be the enemy commander, which was a much riskier task, but one giving the highest return in case of a success.
Similarly, in the Pacific theater, one of the factors leading to the superiority of Japanese aces such as the legendary
Hiroyoshi Nishizawa (about 87 kills) could be the early technical dominance of the
Mitsubishi A6M "Zero" fighter.
Post World War II aces
Korean War of 1950–53 marked the transition from
piston-engined propeller driven aircraft to more modern jet aircraft. As such, it saw the world's first jet-vs-jet aces.
North Vietnamese air force was the world’s sixth largest air force at the height of its power in 1974 but armed with mostly obsolescent aircraft. This allowed many North Vietnamese pilots to claim "ace" status. American air-to-air combat during the Vietnam War generally matched intruding United States
fighter-bombers against radar-directed integrated North Vietnamese air defense systems. American
McDonnell Douglas F-4 Phantom II,
Vought F-8 Crusader and
Republic F-105 Thunderchief fighter crews usually had to contend with
anti-aircraft artillery, and machine gun fire before opposing fighters attacked them. The long-running conflict produced 22 aces: 17 North Vietnamese pilots, two American pilots, three American weapon systems officers or WSOs (WSO is the USAF designation, one of the three was actually a US Naval aviator, with an equivalent job, but using the USN designation of Radar Intercept Officer or RIO).
Middle East conflicts
, an ace fighter pilot in the Iranian Air Force. The most successful F-14 Tomcat pilot ever with eight confirmed and three probable kills during the Iran-Iraq war.
The series of wars and conflicts between Israel and its neighbors began with Israeli independence in 1948 and continued for over three decades. Of the 50 known aces during these battles, one was Egyptian, three Syrian, and the rest Israeli.
Jalil Zandi (1951–2001) was an ace
fighter pilot in the
Islamic Republic of Iran Air Force, serving for the full duration of the
Iran–Iraq War. His record of eight confirmed and three probable victories against Iraqi combat aircraft qualifies him as an ace and the most successful pilot of that conflict and the most successful
Grumman F-14 Tomcat pilot worldwide.
Shahram Rostami was another Iranian ace. He was also an F-14 pilot. He had six confirmed kills. His victories include: one MiG-21, two
MiG-25s and three Mirage F1s.
The Iran-Iraq conflict also saw the only known helicopter dogfights in history.