The changing battlefield air defence (I)

I noticed that I didn't explain my interpretation of all things battlefield air defence properly, so I'll do this military theory series to explain. Keep in mind - as always - it's but an interpretation, and I may be wrong. One good reason to believe me to be wrong is that air defence is a very technology-driven area of warfare, and thus outsiders are prone to forming wrong conclusions because of incomplete information. What I'm writing here may very well be true, but it may just as well be outdated by 10-20 years concerning the state of the art. Also note that I will ignore ballistic missile defence, naval air defence as well as 'strategic' land-based air defence in this series.

First, the military history part:

Historically, battlefield air defences began with 75-88 mm guns mounted on platform motor vehicles. They were meant to provide a mobile force to destroy enemy airships and tethered balloons. Ambitious plans called for hundreds of such self-propelled anti-air guns even before the First World War. The First World War showed that the external ballistics of such guns were insufficient to repel tethered balloon deployments to a distance from which their observation was useless. Airships could not dare to fly over territory defended like that in daytime, though. Such anti-air guns shot a lot at aircraft, but the fire control was insufficient even against the less than 200 kph fast, less than 5,000 m high-flying targets. Barrage fires were used to protect the own tethered observation balloons against hostile aircraft. Machineguns proved to be important to discourage or weaken the attacks by aircraft on ground forces.

Little happened during the Interwar years, but some of the WW2 AAA were developed, among some anti-aircraft gun solutions that were failures. Much was invested in fire control, but without the appropriate attention to the correct approaches to fusing and shell steel brittleness.

During WW2 all guns weaker than 30 mm proved to be a disappointment; 20-25 mm guns were effective only at very short ranges, and with a great volume of fire. They required multiple hits for one kill, so they were more a deterring and damaging anti-air arm than a killing one. 30-40 mm guns were powerful enough to kill most aircraft with a single hit, but their range was insufficient against medium bombers. Most 37-40 mm guns had a poor rate of fire and were effective to about 3,000 m diagonal range. Their shells were often set to self-destruct after about 3,500-4,000 m of flight. The expense of such a battlefield air defence (including the usually necessary motor vehicle as tractor and the often preferred additional motor vehicles to enable a battery to march as one) was great, and even thousands of such guns were inadequate to properly defend against the fighter-bomber and Shturmovik threat.

Heavy AAA was of little importance to battlefield air defences. Intermediate AAA (45-55 mm) was a gap-filler that was hardly ever used.

Post-WW2 radio fire control became much more widespread, though even the self-propelled anti-air guns with their expensive platform vehicle and support often lacked radar fire control (examples M42, ZSU-27-2). technologically sound SPAAGs were available around the year 1970 (ZSU-23-4, Gepard, AMX-13DCA), but a vehicle such as a Gepard did cost three times as much as a concurrent main battle tank (Leopard I), so the SPAAG force that was mostly meant to protect the tank force almost approximated the latter's costs. Less ambitious SPAAGs were in service as well, with incomplete radar fire control (example M163 VADS) and accordingly cheaper, but also much less capable and thus required in even greater quantity.
Missiles began to complement guns for battlefield air defence in the late 60's, famously the semi-mobile SA-6 batteries of Yom Kippur War fame. Man-portable missiles (Redeye, Igla) and air combat missiles adapted for air defence (Chapparal) were of little consequence in the 70's because they were limited to tailchasing with their infrared seekers. Dedicated self-propelled air defence vehicles (Roland, SA-8) were more capable, but also expensive (and their towed equivalents such as Rapier were a rare compromise).
A reasonable, but not very mobile  budget solution of the 60's to the 80's was to combine a fire control radar with several towed guns (usually 30-57 mm calibre). Heavy AAA had largely lost its relevance because the long time of flight beyond 57 mm range and the high speed of turbine-powered aircraft made preventive evasive manoeuvres extremely effective against guns.
An exotic system was the Swedish RBS 70 with its laser beamrider guidance, which allowed a crew-portable battlefield air defence to engage air targets from all aspects within a reasonable range.

The 80's saw little change; the arrival of infrared guided missiles that would almost reliably lock on aircraft head-on made them a bit more effective (though their effectiveness was exaggerated).

Post-Cold War we saw a rise of a few SPAAG designs with complementary missile armament (Tunguska, LAV-AD), but they shared an important problem with most other battlefield air defences; the effective ceiling was lower than the maximum effective altitude for precision attack on land forces. The sensors (particularly thermal cameras coupled with instant laser rangefinders) had advanced to a point by the late 1980's that most battlefield air defences were merely able to push air threat above the effective range of anything but short dive bombing/rocketing attacks (= what the Soviets continued with good success and very few losses in Afghanistan after the arrival of Stinger missiles).

Area air defence batteries with longer-ranged, higher-ceiling missiles would be needed to complement the short range air defences (ShoRAD), but particularly the NATO countries trusted their air forces to achieve air superiority if not air supremacy quickly, and didn't invest much in such systems. What systems were available (mostly Patriot, IHAWK, Skyguard Aspide, recently SAMP/T) were at most enough to satisfy air defence requirements for support assets behind the manoeuvre forces, including bridges, airbases and headquarters. The approach of using (V)ShoRAD to push hostile air threats up where they could be engaged by area air defences was what caused much trouble to the Israelis in 1973 when they faced the SA-6, but it was established already in the Yom Kippur and Vietnam War that attacks on the area air defence batteries (and in particular their radars) would unhinge this teamwork. Russia, France, Israel and the UK committed some resources on dedicated equipment to locate and defeat such radars, but it was the U.S. that invested greatly and used this investment to bomb the Iraqis almost with immunity, but it was the Yugoslavs who showed that tactics could degrade such anti-radar efforts from destruction (DEAD) to suppression (SEAD), which meant that a sizeable share of the superior hostile air power was fixed in the anti-air defence mission indefinitely. The rapid consumption of expensive anti-radar missiles would be unsustainable and unsuitable for a large air war.
I recommend "On Air Defense" as a book to those who want to read more on the history of air defense.


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