I wrote some about this topic for years, but this time I'll attempt a concise summary. It's just opinion, of course.
It is easy to find folks who believe air power rules over land campaigns and land battles, Brimstone missiles could eradicate entire hordes of tanks, air power provides all-seeing eyes etc. OK; I'm exaggerating a bit.
|"Air power" symbol picture (CGI)|
Here are my theses:
(1) Air power affects ground campaigns discontinuously
Common practice in face of hostile defences is to assemble strike packages; the most elaborate ones comprise fighters, bombers, tankers, AEW, anti-radar and anti-radio communication components. These components work together to overcome the opposition and accomplish their mission.
There are two drawbacks; these strike packages aren't on station all the time (a husbanding of resources analogous to a Schwerpunkt) and the share of assets actually interfering with hostile ground forces other than air defences may be low, such as 40% for example.
(2) Air power is scarce
Even assuming no hostile fighters and no hostile air defences, friendly air power would not provide continuous support for multiple formations or units in contact at the same time. Some German field manuals advise even battalion leaders that divisional artillery support may be unavailable in combat, being focused on some different (Schwerpunkt or crisis) effort. The same would be true - and even more so - for the theatre-level asset of fixed wing air power. Both the Vietnam War and the conflicts in Iraq and Afghanistan during the last couple years have seen comparably lavish air power support even for mere platoons.
A platoon leader in a war between great powers cannot expect arrival of air support within 20-30 minutes; he could probably not even expect artillery or mortar support, or any non-organic, non-attached support at all.
(3) It's difficult to predict contacts and engagements
Air power can and needs to prepare for activity spikes in advance, but this 'in advance' represents a time lag and is largely unavoidable. Few combat aircraft could be diverted from one mission to another and arrive within minutes. This causes geographical and temporal mismatches between air power support need and availability.
(4) Air power on deep attack is unreliable
Air attacks without assistance from more persistent observers on the ground have a hard time spotting and identifying targets. This was prominently demonstrated in 1999 and 2001.
(5) Modern combat aircraft tend to carry few ground attack munitions
Multi-role combat aircraft are fashionable, and they carry a lot: Fuel tanks, air combat missiles, targeting pods, often anti-radar missiles or jammers. And ground attack munitions. The latter become even fewer when tanker aircraft or close bases are very scarce.
(6) Range issues
The combat radius of a modern combat aircraft is rather disappointing even on hi-hi-hi flight profiles. There's little gain over WW2 in this regard. At the same time, modern combat aircraft are very demanding in regard to base services; maintenance, fuel, ammunition, flight safety and also seemingly simple things such as brake chute repackaging.
Austere bases on motorways are feasible, but they would cause a huge drop in sortie rates within days, and dispersed basing may be entirely unsupportable.
This means sortie rates may disappoint and efficiency may be reduced a lot by long distances between battlefield and operational air base.
(7) The true air supremacy is a tank on the runway
Air power may experience a huge drop in effectiveness during theatre-level crisis situations because forward air bases would be forced to evacuate in face of advancing hostile armoured recce and vanguard elements.
(8) Air power may be unable to harvest much benefit from superiority and destruction campaigns
A superior air force (or alliance thereof) may seek to destroy at least vital components of integrated air defences, it/they may attempt to decimate battlefield air defences and it/they may seek to eradicate fighter opposition. All these activities demand great resources for days if not weeks - resources not used to influence the land campaign directly. Such efforts may also be ultimately fruitless, and the superior air power may be forced to maintain caution throughout the campaign, devote much of itself to suppression efforts (see strike packages mentioned before). The Serbs had some clever tacticians in 1999 and achieved this effect even with clearly obsolete or largely non-operational equipment.
Episodes such as the Great SCUD Hunt of 1991 add to this issue with suppression efforts.
(9) 'We' may be partially technologically inferior sometime
The MiG-29 was a huge shock to NATO when East German aircraft were tested and their pilots interviewed. The IRST, the helmet sight, the jamming-resistance of the radar, the agility and the performance of the R-73 (AA-11) missile were unknown or badly underestimated during the 80's. Obviously, others can develop quality military equipment as well.
'We' are having development projects measurable in decades, and production runs measurable in decades as well (save for the F-22). This means we leave huge temporal windows of opportunity for aggressors; years or even a decade of having inferior air power technology for important missions.
'We' are also very much dependent on few key technologies. A hostile fighter with the equipment to defeat the tiny radar of an AMRAAM missile and the jammable infrared seeker of our typical short range air-to-air missiles would defeat almost all Western air combat capability. Both is feasible and actually to be expected of PAK-FA.
(10) Air power may be allocated for strategic air warfare
Even aircraft can only be at one place at a time, and aircraft on a mission against hostiles' domestic political and economic targets are rather unlikely to help a tank company that's stuck in woodland because infantry blocks a forestry road.
(11) Terrain is still an issue with air power
The prophecies of urban-centric future wars have been heard for decades, but air power is badly restricted in urban battle scenarios. The most relevant urban air power support in recent occupation wars was the availability of attack helicopters overhead, comparable with police helicopters but with weapons of war mounted. This won't be available if the opposing forces are part of an actual army. Even the defeat of infra-red guided missiles and an altitude which protects against 7.62 mm and RPG weapons wouldn't help in face of laser beam rider missiles. Even anti-tank missiles can be very dangerous to attack helicopters. RPGs are merely the short ranged poor man's equivalent.
Also, woodland. Foliage penetrating radars are still not standard, and probably won't become standard any time soon. You cannot identify targets through foliage anyway.
(12) Munitions. Run. Out.
Combat aircraft are prestigious objects. The whole readiness and stocks thing isn't nearly as visible and often neglected. Air power would run out of some modern munitions within weeks during a large-scale air war and other modern munitions would be depleted soon thereafter or disappoint. "Dumb" munitions would come back after weeks and air power efficiency would drop steeply.
The more profound effect would happen earlier; rationing. Within few weeks, air power would become more restricted in its effect because sometimes targets would be rejected, reserving munitions for higher value targets. The "Hellfire hit on a pickup" scenario from Afghanistan would become rare.
(13) Clever reactions to air power diminish much of its power
It was relatively simple to call all coalition air power to the Battle of Khafji in 1991. It's a coordination nightmare if entire logistical battalions or even only entire tank battalions move dispersedly in packets of only three vehicles each.
(14) Overambitious air power may actually have hurt itself
Air power was capable of limiting road and rail movements to the night during 1944-1945. This may not happen again since night attack capability negated night movement's survivability advantage. Instead, movements may be restricted by whether strike packages have been spotted or not. This leads to very different adaptive behaviour and thus possibly to a much lesser troop and supply movement suppression effect.
(15) Dependence on circumstances
Air power will probably never again be that effective against supply services as when 6,000+ Allied combat aircraft faced an army which counted its in-theatre trucks in the mere thousands and was heavily dependent on railroad services. Nowadays NATO may muster a thousand or more combat in a theatre of war, but might face an enemy having the choice of hundreds of thousands of civilian trucks for the logistical effort.
Air power interdiction efforts may be very much dependent on geographical bottlenecks in the future, as bottlenecks limit the flow of vehicles and air power can make a noticeable dent on this already limited flow. A campaign of attrition against logistical vehicle inventories is likely going to be a fool's errand even in most of the Third World.
There are of course plenty counter-examples which make air power look near-god-like. A few B-2 bomber sorties could have demolished an entire Russian division on a valley road during the South Ossetia War, for example. And the road as well.
I don't feel the urge to write much about these examples because that's what others do. So this blog post doesn't call for re-allocation of budgets from air power to ground power as much as it's meant to push back against a perceived pro-air power bias.