Strafing is the military practice of attacking ground targets from low-flying aircraft using aircraft-mounted automatic weapons ranging from machine guns (5mm to 20mm) to autocannons or rotary cannons (typically 20mm to 37mm). This means that, although ground attack using automatic weapons fire is very often accompanied with bombing or rocket fire, the term "strafing" does not specifically include the last two. The term "strafing" can cover either fixed guns, or aimable (flexible) guns. Fixed guns firing directly ahead tend to be more predominant on fixed wing aircraft, while helicopters tend to use aimable weapons which can be fired in many different directions independent of the direction the aircraft is pointing in (in most cases, flexible guns on a fixed wing aircraft are for defense purposes only, although they can sometimes be used to fire on ground targets to limited effect). Some fixed wing aircraft, like fighter-bombers, are capable of flying either air-combat missions or ground attack missions (P-47 Thunderbolt), while others are dedicated ground-attack types (Il-2 Shturmovik). In cases where an aircraft is capable of both types of combat, when it is assigned to a ground attack role, and thus expected to be using the guns mostly for strafing, the fixed weapons are often mounted so that the convergence point is lower and at a greater range than would be used for air combat. This is helpful because it allows the pilot to aim at a target without having to dive towards the ground as steeply, decreasing the risk of collision with the ground and increasing the amount of firing time available before having to pull up, and it also increases the range from the target, helping avoid anti-aircraft fire and potential damage from exploding targets. Because of the low altitude and relatively low airspeed required for accurate strafing, it is very risky for the pilot, who is exposed not only to the risk of flight-into-terrain and obstacles such as power lines, but also to anti-aircraft weapons, including surface-to-air missiles (both vehicle mounted and hand-held), anti-aircraft artillery and small caliber weapons fire (such as machine guns and small arms). Planes purposely designed for ground attack may include additional armour around and underneath the cockpit and other vulnerable areas such as engines to protect the pilot and key flight components, while aircraft designed mostly for air combat tend to have most of their armor placed to protect directly ahead or to the rear, where fire from other aircraft is most likely, leaving them more vulnerable to fire from directly below or to the sides, where much ground fire often comes from.
Less commonly, the term can be used—by extension—to describe high-speed firing runs by any land or naval craft (e.g. fast boats) using smaller-caliber weapons and targeting stationary or slow-moving targets.
The word is an adaptation of German strafen, to punish, specifically from the humorous adaptation of the World War I German catchphrase "Gott strafe England" (May God punish England).
World War I
While the earliest use of military aircraft was for observation and directing of artillery, strafing was frequently practised in World War I. Trenches and supply columns were routinely attacked from the air in the second half of the war. Strafing with machine guns was used when precision was needed (facing small targets), but non-strafing attack methods (primarily small bombs) were preferred for larger targets, area targets, or when low-altitude flying was too risky.
The German army was the first to introduce a class of aircraft specially designed for strafing, the ground-attack aircraft. Planes built specifically for strafing include the German World War I Junkers J.I, which was armored to protect it from ground-based gunfire. The Junkers J.I. had two downward-facing machine guns that were used for strafing.
World War II
These developments continued through World War II with dedicated aircraft including the concept of the heavily-protected cockpit or "bathtub" to permit the pilot to survive counterfire from anti-aircraft batteries.
The Luftwaffe's best strafing plane was the Junkers Ju-87 Stuka. The Ju-87 G variant had two Rheinmetall-Borsig 37mm Flak 18 guns each mounted under the wing.
For the RAF the best ground attack plane was the Hawker Hurricane II. It was armed with four 20 mm (.79 in) wing-mounted cannon. The Hawker Typhoon was used in the later stages of the war. It had four "60 lb" RP-3 rockets.
For the US, the Republic P-47 Thunderbolt was one of the key ground attack planes. It was armed with eight .50 calibre machine guns. Another aircraft that was important in that role was the North American B-25 Mitchell. It was used for low-altitude strafing runs in the Pacific War.
The Russian Ilyushin IL-2 Sturmovik was one of the key Russian ground attack planes. It had heavy armour around the engine, underside and canopy. It was armed with 20mm to 23mm to 37mm cannons depending on the model.
An RCAF Spitfire of 412 Squadron piloted by Charley Fox strafed the command car of Erwin Rommel on 17 July 1944 near Sainte-Foy-de-Montgommery, affecting his possible participation in the 20 July 1944 Operation Valkyrie coup.
In the Korean War in 1950–1953, USAF planes strafed targets deep behind the front line and had a perceptible impact on the progress of the ground war - but the concept of strafing was already in decline.
In 1960s, when precision-guided weapons became widespread, strafing temporarily fell out of favor as unnecessarily risky— some American fighter aircraft or attack aircraft of that time (such as the F-4 Phantom and A-6 Intruder) did not have built-in cannon or machine guns. In the Vietnam War, this was found to be a deficiency, and improvised "gunships" had to be used in strafing missions.
The A-10 Thunderbolt II is an American twin-engine, straight-wing jet aircraft developed by Fairchild-Republic in the early 1970s which is the only United States Air Force aircraft designed solely for close air support of ground forces. The A-10 was built to attack tanks, armored vehicles, and other ground targets with limited air defenses.
The A-10 was designed around the GAU-8 Avenger, a 30 mm rotary cannon that is the airplane's primary armament and the heaviest such automatic cannon mounted on an aircraft. The A-10's airframe was designed for survivability, with measures such as 1,200 pounds (540 kg) of armor for protection of the cockpit and aircraft systems that enables the aircraft to continue flying after taking significant damage. The A-10's official name comes from the Republic P-47 Thunderbolt of World War II, a fighter that was particularly effective at close air support. The A-10 is the main US plane designed to do strafing runs.
Since 2001, Coalition pilots in Iraq and Afghanistan have used strafing runs to support ground forces in areas where explosive ordnance could cause unacceptable civilian casualties. Strafing runs done by F-16s are very risky for the pilot. The cities of Damascus and Aleppo were strafed by helicopter gunships in the Syrian civil war.
The AC-130 Gunship, which is equipped with rotating-barrel Gatling guns, is specifically designed for strafing ground targets.
In 2004, the United States Air Force accidentally strafed one of its own country's middle schools in the strafing of the Little Egg Harbor Intermediate School incident.