Assuming that the cockpit framing and bulletproof windscreen didn't get in the way, individual fighter-sized aircraft could usually be seen perhaps two miles away, four-engine bombers from three or four. A formation or group of aircraft could sometimes be seen six or seven miles away. Visual detection range could be doubled if enemy aircraft were maneuvering. However, aircraft could not be seen by anyone looking directly at or close to the sun, and clouds could provide concealment.
To mount a coordinated attack on a target, it was necessary for a group of fighters to fly in formation. The number of aircraft in the formation and their positions had a relatively large influence on the aircrafts' effectiveness and survivability.
Before World War II, the basic formation used by many air forces (including the British Royal Air Force [RAF]) was a V or "vic" of three aircraft flying very close together, about a wingspan apart. A squadron was typically composed of four vics. This was fine for air displays and flying in cloud, but its severe disadvantage was that every pilot except the formation leader was concentrating on maintaining formation, leaving little time to look for enemy aircraft. Considering that about 80 percent of all pilots who were shot down never saw their attackers, the folly of using this type of formation can be readily understood. Several instances are recorded of a single enemy plane shooting down two or three aircraft without the rest of the formation noticing anything amiss.
The Luftwaffe had learned from combat experience in the Spanish Civil War, and at the urging of Werner Mölders, a leading German fighter pilot in Spain, it adopted a widely spaced Rotte (pair) as the basic tactical unit, the two aircraft flying a few hundred yards apart. Each pilot was then free to search for enemy aircraft without worrying about avoiding collision and could easily check the other's blind area, making a surprise attack less likely. When the formation leader attacked a target, the wingman's duty was to guard his leader's tail. The basic unit of maneuver was two pairs arranged side by side like the four fingers of a hand, with the leaders of the pairs at positions two and three. When the RAF and most other air forces eventually adopted this formation during 1941 and 1942, it was usually known as the Finger Four.
The U.S. Navy adopted a variation of this in which the pairs flew farther apart (about one turn radius). When either of the pairs was attacked, the two pairs turned toward each other, providing one pair with a head-on shot at the other pair's attacker. This tactic was known as the Thach Weave after its originator, Lieutenant Commander John S. "Jimmy" Thach. A variant was used by the Soviet air force later in the war. The Soviet air force also learned lessons from the Spanish Civil War, but many of the officers who might have been able to make a systematic change were removed in Josef Stalin's purges.
The nature of fighter-versus-fighter combat is such that the greatest chance of success is to be obtained by gaining a position advantage on an opponent, making a single unobserved attack, and then breaking off. This is essentially the technique used by German ace Erich Hartmann on the Soviet Front. There are numerous recorded instances of this technique working for a single attacker against a large formation of aircraft. The fact is that a single aircraft is much more difficult to spot than a formation, and a formation is more difficult to control than a single aircraft.
A position advantage is really any position that allows an aircraft to launch an attack, the precise nature of which will vary depending on the characteristics of the fighter and target aircraft. When attacking single-seaters, this was somewhere in the rear hemisphere of the target, preferably positioned so that the target would have to look into the sun to see the attacker and usually positioned higher so that the fighter could dive on the target with a speed advantage. The fighter would then open fire in the dive or would dive below the target and shoot in a shallow climb. This variation was favored by German ace Adolf Galland. Many aces were good shots; some went very close to their targets—a few yards, in some cases—to be sure of a kill.
The art of air-to-air gunnery is to ensure that the projectiles and target arrive at the same point in space simultaneously. To accomplish this, the pilot must aim some distance in front of the target; this is called the deflection angle. This applies only unless the shooter is immediately behind the target or attacking head-on. Some pilots were able to instinctively apply the correct amount of deflection, but most could not. The British introduced the Gyro Gun Sight in 1944, which dramatically increased the number of hits scored by the average squadron pilot.
Having delivered the attack, the pilot could then either break off combat or convert his speed advantage into an altitude advantage and reattack if necessary. This tactic could be particularly effective if the fighter had good dive acceleration and zoom-climb capabilities (e.g., Messerschmitt Bf-109, P-51 Mustang).
The usual counter to a fighter attack was a very hard ("break") turn toward the attacking aircraft to present a difficult firing solution. After the attacker had fired, several possible courses of action were open to the defender—assuming, of course, that the attacker had failed to do significant damage on his first pass. If the attacker was forced to overshoot, a roll reversal back toward the attacker could yield a firing solution for the defender, but this would probably be fatal if the attacker had a wingman. This maneuver could degenerate into what in current terminology is called a "scissors"; in it, each aircraft repeatedly turns hard toward the other to try to force an overshoot. The advantage in this case would usually be with the aircraft that had the lower wing loading, although pilot skill played a part.
Alternatively, if the attacker continued turning in an effort to get a firing solution and was flying a significantly more maneuverable aircraft (e.g., Spitfire IX versus Messerschmitt Bf-109G or Mitsubishi Zero versus Curtiss P-40), the defender's best option was to break off the engagement. The preferred method of doing this varied with the aircraft's relative capabilities. If the attacker did not have a significant top speed or dive advantage, a favored technique was to half-roll and enter a full-throttle vertical dive (the "split-s" or Abshwung). This could lose as much as 10,000 ft of altitude, and if the attacker did not also immediately dive, the defender would usually be able to get sufficient separation and speed to break off the engagement. Finally, if the defender had a maneuverability or performance advantage, he could elect to stay and fight it out by turning hard to get onto his opponent's tail. If his aircraft had a significantly lighter wing loading, three or four circles were usually enough to gain a firing position.
If a formation of disadvantaged aircraft were attacked by enemy aircraft, a viable tactic was to form a defensive circle or "Lufbery," named for a famous American World War I fighter pilot. In this tactic, the defenders flew in a circle so that each aircraft covered the one in front. An attacker would then have to fly through the field of fire of the following aircraft to attack any aircraft in the formation. The defensive circle could be a double-edged sword; during the Battle of Britain, Spitfires were able to get inside defensive circles of Messerschmitt Bf-110s flying in the opposite direction and were able to engage each aircraft in turn without exposure to significant enemy fire. In June 1942, German ace Hans Joachim Marseille managed to shoot down six South African P-40 Tomahawks over Libya by making repeated diving and zoom-climb passes inside a defensive circle and shooting at very high deflection angles.
If the target aircraft had a second crew member, the priority was to approach in such a way that the target was not aware of the presence of the fighter. In the case of a two-seater, this usually meant attacking from below and behind out of the field of fire of defensive weapons. If an unobserved approach was impossible (e.g., for a well-armed four-engine bomber), the choices came down to either approaching from a direction that had poor defensive coverage (e.g., from the beam if the target only had nose and tail weapons) or approaching in such a way as to present a difficult target for defensive weapons (e.g., with a large speed advantage from the rear quarter). If the attacking pilots could shoot accurately, however, the frontal attack was a better and possibly safer option. Bombers usually had fewer and less-effective weapons firing forward, the attackers were exposed to defensive fire for a much shorter period of time, and the bomber's defensive armor was designed to protect from attacks originating from below and behind the bomber rather than from the front.
If the target had defensive armament and was flying in formation, the other aircraft in the formation would be able to contribute defensive fire, and attacking became significantly more hazardous. The effect of defensive fire could be reduced by making multiple simultaneous attacks or by selecting a target on the edge of the formation. Some antibomber weapons (e.g., the German Wgr-21 rocket) were designed to break up formations and allow individual targets to be picked off.
Late in the war, German jet fighters were used against bombers, and the amount of excess speed generated in a dive made sighting extremely difficult. To cope with this, a roller-coaster–type attack was developed whereby the attacking jets approached from the rear of the formation, dived through the fighter screen at speed to a position 1,500 ft below and behind the bombers, and then pulled up into a steep climb to bleed off most of the excess speed before selecting a target and opening fire.
The tactics employed by radar-guided night fighters were concerned more with accurate interception techniques and visual acquisition before firing than with violent maneuvering, although there were exceptions. The tactics were dominated by the target-acquisition performance of onboard radar; the British AI Mk IV had an effective range of 3–4 miles at 15,000 ft, degrading to half a mile at 3,000 ft. The minimum usable radar range was usually about 1,000 yards and the maximum visual acquisition range was usually about 1,400 yards, although this varied depending on moon and cloud conditions.
Most home-defense night fighters relied heavily on ground controllers, although both sides had electronic devices that allowed a fighter to home onto a target from many miles away. The Germans had a Flensburg receiver that homed onto the Monica tail-warning radar and Naxos that detected H2S bombing radar; the British had Serrate, which homed onto German airborne radar transmissions and Perfectos that triggered German aircraft IFF (Identification Friend or Foe) equipment.
Ground control and radar operators usually aimed to approach the target from astern and from slightly below so that the target was silhouetted against the night sky, maximizing the chance of visual acquisition. Very low targets were, however, usually approached from above to maximize radar detection range. German night fighters fitted with Schr?ge Musik (upward-firing cannon) could attack from almost directly below the target and were very effective against RAF bombers until the tactic became known.
Franks, Norman. Aircraft versus Aircraft. London: Grub Street, 1998.; Price, Alfred. World War II Fighter Conflict. London: Macdonald and Janes, 1975.; Spick, Mike. Luftwaffe Fighter Aces: The Jagdflieger and Their Combat Tactics and Techniques. Mechanicsburg, PA: Stackpole Books, 1996.; Spick, Mike. Allied Fighter Aces of World War II. Mechanicsburg, PA: Stackpole, 1997.