Air Defence and ASW are on the menu:
Just for fun:
When you can measure what you are speaking about, and express it in numbers, you know something about it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts advanced to the stage of science - Lord Kelvin
For as long as there have been carrier related discussions on various forums, people have claimed that because a maritime task group can be supported by long range aircraft such AWACS and MPA types, and tankers, then the same must be true for fighters, and that there is no advantage to having aircraft close to the shore for dealing with land targets. Ongoing operations in the Red Sea suggest otherwise.
Before he went off piste and became unaware of the value of low observerability and advanced avionics, and the advances made in V/STOL aircraft propulsion and controls, Sharkey Ward often made sense. In Sea Harrier Over The Falklands he says that when he was in a MOD job post Falklands, he pointed out that:
To put fighter cover over the fleet at just a few hundred miles would take up all the tanker resources of the RAF and most of the fighters.
He does not develop this argument further. He does not say exactly what he means - the same level of cover as provided by multiple US carriers each with two Squadrons of Tomcats? Despite being a fairly numerate Engineering student when I first purchased and read his book, I have never tried to do the speed/time/distance calculations - until just over a week ago.
Scenario
Vlad The Invader and his henchmen are on the rampage. Eastern Europe, and the Baltic States are in his sights as she seeks to recreate the Russian (ie pre Soviet) empire. He also plans to attack Norway to seize airfields and ports with access to the Norwegian Sea and Atlantic beyond. LANDCOM has asked SACEUR to request transatlantic reinforcement, and protecting the crisis response shipping falls to MARCOM. MARCOM also has maritime logistics within European waters to protect, as well as the option of using amphibious forces. Moscow makes noises about NATO reinforcements being a threat to peace and threatens to sink them. Although the Russian surface fleet is in a sorry state, it does possess surface combatants with long range missiles. A more serious threat is posted by the Northern Fleet's submarine force and Russia bombers, coming around the North Cape and losing of multiple anti ship missiles. A number of vessels that are part of the Crisis Response Shipping are in the Norwegian Sea, approximately half way between the UK and Norway. Fifty nautical miles to the South there is one of our carriers.
Assumptions
I am assuming that the airfields in the UK and Norway are both 300nm away, that land and carrier jets both have three hour endurance, that they both transit at a speed of 600kt, and that technical issues occur at a rate proportional to the time in the air. The planned CAP station is 50nm ahead of the ships loaded with reinforcements.
No CAP
Without a CAP and incoming raid will have to be dealt with by either jets on deck alert or ones scrambled from ashore. Assuming an average 600kt transit the deck alert jets will be on station in ten minutes, but the land based ones will take thirty.
24 hour CAP
Carrier launched:
Transit takes 10 min THEN 2 hours 40 min (160 min) on station before return to the carrier
In 24 hour (1440) min: 1440/160 sortie pairs needed for CAP
= 9 sorties pairs
= 18 sorties
If there are eight jets embarked, then that is 18/8 sorties per jet per aircraft
= 2.35 sorties per day for each jet – achievable
7.05 hours airborne per jet every day
Land based 300nm away
Transit takes 30 mins, as does return, leaving 120 min on station
1440/120 = 12 sortie pairs
= 24 sorties
If squadron of eight aircraft then 3 sorties per day for each jet = 9 hours airborne
If the shipping to be protected moves and is now 400nm away
Transit takes 40 min, as does return, leaving 100 min on station
1440/100 = 14.4 sortie pairs per day
=28.8 sorties
28.8/8 = 3.6 sorties per jet every day = 10.8 hours hours airborne
If the shipping to be protected moves again and is now 500nm away
Transit now takes 50 mins – so time on CAP now 80 min
1440/80 = 18 sortie pairs needed
= 36 sorties
36/8 = 4.5 sorties per jet per day = 13.5 hours airborne
If the shipping moves again and is now 600nm away
60 min on station
1440/60 = 24 sortie pairs
=48 sorties
=6 sorties per aircraft per day = 18 hours airborne!
If we assume that the aircraft cannot do this, and assume that two hours maintenance are needed for every flight however, then each jet can only fly for 8 hours per day - 480 mins. Are more jets needed?
No of aircraft needed = no of sorties x sortie time/Max flying time per aircraft
In our case N = S180/480, which can be simplified to N = 0.375 S
Using the figures from above:
Carrier 100nm from CAP station: N = 6.75(round up to 7 aircraft)
Land based 300nm from CAP station: N = 9 aircraft
Land based 400nm from CAP station: N = 10.8 (round up to 11 aircraft)
Land based 500nm from CAP station: N = 13.5 (round up to 14 aircraft)
Land based 600nm from CAP station: N = 18 aircraft
Conclusions
1. The value of having your air defence aircraft near, as part of the force, is clearly demonstrable. Apart from question of a single CAP or a pair of aircraft on alert, there is the issue of what if you need additional aircraft to deal with mass attacks.
2. Even a small carrier, or a larger carrier with a small number of fixed wing aircraft, can play an important and potentially war winning air defence/AAW role.
3. A larger carrier and/or larger number of jets allows you to do far more than a single CAP at 100nm.