By peeling back the layers we can determine the absolute bare minimum the UK requires to defend its territory.
Firstly we identify that threats come from the air and the surrounding seas. In terms of air threats there are two main variants: low-level (strike jets and cruise missiles) and high-level (bombers and ballistic missiles). For the seaborne threats we also have two main variants: surface ships and submarines. We can now examine each of these in turn and design a simple defence for them all, remembering the (Detect, Identify and Engage) DIE mantra.
Low-Level Air Threats
As mentioned above these could be low-level strike aircraft like Tornado or cruise missiles like Tomahawk. Due to the density of the air at low-level they are likely to be subsonic or slightly supersonic. Although it is acknowledged that supersonic and hypersonic missiles exist, their range will be such that they will have to be launched by a high-level air or a seaborne asset.
Low-level threats can only be detected when they pop-up over the horizon. Due to the curvature of the Earth this is likely to be 30-50km away, but the higher we place our observer the further we can see. We therefore need a ground radar station.
If we use a 30-50km minimum we can see that a 300 m/s (Mach 0.9) missile might take 100 seconds to hit us from first detection and a 500 m/s jet (Mach 1.5) will take much the same time as it will be flying slightly higher than the missile and therefore be seen slightly earlier.
We therefore have 100 seconds to scramble our jets and intercept the threat. This obviously isn’t going to happen so we need to use a more rapid response. We need Surface to Air Missiles (SAMs) that can be directed and controlled by the radar that first picked up the threat.
High-Level Air Threats
A bomber is likely to cruise at around 11,000 meters, which can be seen by our ground radar at about 400km. If travelling at Mach 0.9 at this altitude we have a time-to-target of about 25 minutes. This is plenty of time to scramble some jets, journey out to the threat, identify the contact as a threat and engage it if necessary.
We therefore need an airstrip and a squadron of interceptors on standby. The above radar and missile battery therefore needs to be co-located so that they can defend this airbase.
We need a squadron because we always scramble two jets at a time (lead and wingman). We then need to be able to scramble two jets 24 hours a day, 365 days a year. A total of 8760 hours a year. You and I generally work 220 days a year for 10 hours a day (including some time commuting). This represents 2200 hours a year. We therefore need four pairs to cover the whole year. In addition we need to budget for attritional losses, and planned and unplanned maintenance.
Given that each pilot requires 15 hours a month to maintain currency we can use this as the minimum and maximum airframe utilisation. In other words we can determine how many aircraft we need to procure to provide this QRA service for a given period.
Let’s assume we have 12 pilots. This means 180 flight hours per month. We wish to deliver this service for 25 years, which yields 54,000 flight hours in total. If each aircraft delivers 6,000 flight hours we need only 9 aircraft. But since we need eight aircraft “on line” and around four more for sustainment, it is reasonable to procure 12 aircraft and use them over a 33 year lifespan. Alternatively we can support 16 pilots for 25 years.
Sea Surface Threats
Without airborne surveillance we will never see a warship until it is too late. Fortunately warships travel relatively slowly, cruising at around 15 knots and sprinting at 30 knots.
If we fit a surface search radar to an aircraft we could see a ship up to 200 nautical miles away. This gives a time-to-target of over six hours even if the ship is sprinting. We therefore need to undertake a maritime patrol sortie four times a day.
Two Unmanned Aerial Vehicles (UAVs) working back-to-back with a third spare should be able to deliver this requirement but we will still need four crews due to the number of hours they are expected to work. It might seem a little excessive but it might be more sensible therefore to procure four aircraft and bond the crew to the aircraft for planned maintenance and rest cycles.
We would then scramble the above jets to identify and engage the contact. This means that the above jets become more than just air-to-air interceptors. We now require them to undertake maritime strike, which means they need standoff anti-ship missiles.
The most sensible jet aircraft to procure for both these roles right now is the F35A.
The same aircraft we are using for surface threat detection can be used to search for periscopes or the wake left by a submarine. At 11,000 meters cruise altitude however it will not be able to search for magnetic anomalies.
If the aircraft can drop sonobuoys we can also maintain a detection “net” around our waters. This immediately stops the aircraft being a UAV, which is a shame as an unmanned flying radar would probably be the cheaper option. Once our aircraft is large enough to carry 120 sonobuoys it might as well have the capability of dropping anti-submarine torpedoes from high altitude, and undertake Search And Rescue (SAR) missions.
This makes our Maritime Patrol Aircraft (MPA) four Boeing P8 Poseidon.
If we stick with the UAV patrol aircraft we would need to procure half a dozen Merlin ASW helicopters to identify and engage the contact. However, without a plethora of submerged sonars (from our own ships and subs) around our waters we are unlikely to know where the submarine threat exists.
Our shopping list for basic defence of the UK consists of:
- 1 x airbase
- 1 x high-powered ground radar station
- 1 x surface to air missile battery (CAMM or Aster15)
- 12 x Lockheed Martin F35A (plus training pipeline)
- 4 x Boeing P8 Poseidon MPA
This unit should be located near Inverness (e.g. RAF Lossiemouth) and can monitor and defend out to a radius of about 1000km.
A smaller version of the above unit could be used to defend our oversea territories and would consist of an airbase, a radar, a SAM battery, 6 x F35A and 3 x Merlin HM2.