Restoring the UK’s maritime patrol aircraft capability (Part 2)

In part 1 we examined the background to the UK MPA programme and the P-8A Poseidon Aircraft itself. In part 2 we will look equipment integration and the role of the aircraft in service.

P-8A, the high flyer

MPAs have historically operated at medium or low altitude over the sea. This requirement primarily comes from the need to be able to drop sonobuoys or weapons accurately. Dropping an ASW homing torpedo with a small parachute required the MPA to descend a low as 100ft. Based on the 737, a commercial airliner designed to cruise efficiently at around 30,000 ft, the P-8A is intended to operate predominately at much higher altitudes than legacy MPAs. Low flying uses more fuel and demands a more rugged airframe able to cope with the thicker, more turbulent air. Contrary to popular belief, the P-8 airframe has been strengthened for this regime and can perform well at low altitude. During the first part of its life in service with the US Navy, it has been operating predominantly down low. This is partly because the adapted weapons and sensors needed for use at high altitude are not yet available.

There are considerable advantages that will come when the P-8A is able to routinely fly at higher altitude, including greater fuel efficiency. With just 9 aircraft available, the time on station dictated by fuel consumption will be particularly important for the UK P-8s, especially as the RAF cannot provide its own air-air refuelling for them. Aircrew also suffer less fatigue in the smoother air at altitude.

Increasingly sensitive sonar means the noise of low-flying aircraft can be detected by submarines at times. Various attempts have been made to develop submarine-launched anti-aircraft missiles, and it is only a matter of time before they are perfected and become a lethal threat to aircraft at low-level or helicopters. For search & rescue and surface surveillance missions, flying at higher altitude also vastly increases the sea surface area that can be surveyed by the multi-mode radar, electro-optical/infrared camera. The USN is developing the Multi-Static Active Coherent (MAC) system which uses dispersed active and passive sonobuoys, greatly enhancing submarine detection capability. This new generation of sophisticated sonobouys with modern batteries are able to work for longer, have GPS to track their exact position and allow one aircraft to handover monitoring to another aircraft or ship. The powerful onboard processing capabilities of the P-8A are intended to interact with widely dispersed sonobuoy fields from high altitude.

Of course, if within range of enemy warships and land batteries equipped with medium/long range anti-aircraft missiles (such as the lethal Russian S300/400 series) the aircraft becomes far more vulnerable than at low altitude. The increment 3 P-8A does not have a full set of robust countermeasures such as radar jammers and decoys needed to protect it from modern SAM systems.


Buying all-American aircraft and kit

It is clear from MoD statements that the UK will be buying the P-8A directly “off the shelf” with no modifications and no plan to integrate UK weapons. The platform has successfully evolved in a series of increments, with capabilities added over time. The UK will get aircraft fitted to Increment 3 standards, identical to those being delivered to the US Navy. Initially, the UK will have to purchase a stock of US Mk 54 torpedoes. Performance is classified, but the British-made Stingray Mod 1 Torpedo is probably slightly superior to the Mk 54. Both weapons experienced development problems, but the Stingray is now very mature, while there are still question marks about the Mk 54 in demanding environments.

A British company, Ultra Electronics is the world leader in sonobuoy manufacture and is continues to work with QinetiQ in conducting research and development supporting the Merlin ASW platform. There will be little UK-supplied sonobuoy and acoustic processing input into the P-8A, at least initially. The sonobuoy is a British invention but the P-8A will not benefit from the considerable UK expertise available in this field. The P-8 processors and dispenser are not fully compatible with UK sonobuoys, so US stocks will have to be acquired. The UK will have to support the cost of two parallel inventories of, sonobuoys and torpedos, but there may be some operational advantages of commonality with US equipment. RAF, US and Norwegian P-8As will all be able to share a common pool of stores and spares held RAF Lossiemouth, Keflavik Air Base (Iceland) and other US bases.

In order to be effective at higher altitude, the US is developing two specific enablers. Boeing has the contract to build a glider kit for the Mk 54 torpedo, the High Altitude Anti-submarine warfare Weapon Capability (HAAWC). HAAWC integrates an air-launched accessory (ALA) kit with a GPS guidance system and folding wings. This will allow the launch of the weapon from 30,000ft under operator control so the torpedo can be put into the water with precision and at the considerable distance from the aircraft that launched it.

BAE Sytems in the US is developing the High Altitude ASW (HAASW) Unmanned Targeting Air System (UTAS). This is a small dispensable drone equipped with a Magnetic Anomaly Detector (MAD) that can be dropped from the P-8A weapons bay at high altitude. Previous MPAs (and India’s P-8i) have a MAD boom on the tail of the aircraft which require the aircraft to fly at low level over the suspected contact. Small changes in the earth’s magnetic field are detected if there is a submarine present. MAD has only a short detection range but is a useful tool for localising and confirming the presence of a submarine if no active sonar emitter is available. UTAS will enable this to be done by the P-8A at high altitude without the need to descend.

  • Mk 54 Torpedo P-8

    Mk 54 ASW torpedo being loaded onto US Navy P-8A. At present, this can only be dropped from low level (US Navy Photo)

  • The Mk 54 gets its wings. Due to be dropped by a P-8A for the first time in 2017, this system should be operational by 2020 and available for the UK to purchase.


    A truly obscure piece of defence kit. HAAW UTAS – a MAD equipped drone, being developed by BAE Systems in the US under a $8.9M contract

  • CATM-84D Block IC Harpoon anti-ship missile (training version) carried by USN P-8A. Whether the UK will purchase stocks of this weapons remain to be seen. If so, the RAF could be in the curious position of having anti-ship missiles while the RN has none. (Photo

P-8 Operations

The table below shows the missions the P-8A will be expected to carry out when it enters service plus some additional roles that it could be equipped for. With just 9 aircraft, it is clear the force will be in great demand and raises some interesting questions about how is tasking will be prioritised. A continuous ASW watch over northern waters and GIUK gap would be desirable with an aircraft available to respond to SAR emergencies. Keeping at least two aircraft in the air or at very high readiness would probably require the entire squadron and leave limited options for other tasks. The more numerous Nimrod MR2s were frequently used to provide overwatch and co-ordination for UK military operations around the world. The RAF has an inadequate number ISTAR aircraft and there maybe be pressure to take the P-8A away from its primary maritime patrol duties.

In-service capability Notes Possible future capability Notes
Anti-Submarine Warfare (ASW) Detect, track, classify and potentially prosecute submarines using HAAWC and UTAS Anti-Shipping (ASuW) Would require UK purchase of Harpoon or interim weapons until FCASW* available
Surface surveillance Monitoring of naval and merchant vessels. Anti-smuggling / trafficking / illegal immigration / crime Control of surveillance UAVs Would require UK purchase of long-range UAV such as Trition
Long range search and rescue. (SAR) UK Search and Rescue Region (SRR) amounts to nearly 1.25 million sq nautical miles of ocean Long range strike If existing Storm Shadow missiles or FCASW integrated with P-8A
Mission co-ordination For variety of military operations (land and sea) Minelaying An absurd capability gap, but UK has no existing stock of naval mines
Overland surveillance The P-8A is not specifically designed for this but has some capability.

*FCASW – Future Cruise and Anti-Ship Weapon. An Anglo/French missile in development, but unlikely to be operational before 2030.

Conventional wisdom suggests that a lone MPA will struggle to detect a modern submarine, and should be considered as just one of the essential parts of the ASW matrix that include seabed arrays, ships and other submarines.

A Cold War submarine captain I know once suggested to me that he feels the only way a MPA could find a properly operated SSN was if it bumped into it. “MPA radar is a good deterrent, which makes you keep your head down,” he explained, “but the only time one SNN I commanded was detected by a sonobuoy was when we passed about 20 feet away from it and the contact was fleeting.” Cold War-era British MPAs fared better against the Russians, however. “Nimrods used to get away with it when tracking earlier Soviet submarines,” the SSN captain also observed, “but they were pretty hopeless against a Victor III. Against an Akula, I would have given them hardly any chance at all.” (Iain Ballantyne blog)

The P-8A has some classified capabilities, that are subject to much speculation but may give it the edge in ASW. It is known that it has a hydrocarbon sensor that can detect trace amounts of exhaust from ships, or more importantly conventional submarines snorting (recharging their batteries using their diesel engines). Such leading edge technology, including MAC sonobuoys and powerful onboard processors, justify the high financial cost of the P-8A. This investment may well be vindicated, particularly when up aginst a new generation of very quiet Russian submarines.