How Warships Hunt For Enemy Submarines From A Veteran Submariner Who Has Been Hunted Many Times

Updated Nov 27, 2020 6:13 PM EST

Anti-Submarine Warfare, or ASW, is an evolving practice that requires patience and coordination as much as skill and technique. The tools today’s navies use are much farther reaching and more capable than the simple Cold War-era sonars. Artificial intelligence helps alert operators to potential threats. Advance oceanographic modeling of sound propagation and ray trace help plan highly effective searches across vast stretches of ocean. Complex acoustic pulses at incredible power levels push back the veil of uncertainty before a fleet.

It is in this ASW environment we will review the fundamentals of a basic submarine search, not from another submarine’s perspective, which you can read all about here , but from the point of view of a destroyer or another anti-submarine warfare-enabled surface combatant cruising atop the waves.

Searching for a submarine happens using two basic methods: active sonar search or passive sonar search. Both ways are capable techniques, but they have vastly different strengths and weaknesses.

The most common search is the full spectrum active sonar that fills the volume of water around a ship for tens of thousands of yards with acoustic energy. These updates, or ‘pings,’ can be 10-15 seconds apart. Each transmission maintains a boundary of sound that detects nearly everything when two or more sources (active sonars) are employed.

A single active sonar will not propagate evenly through a medium like seawater. It bends through temperature and density changes. It bounces off thermal layers as if they are solid. This creates vertical, wedge-shaped blind spots called ‘shadow zones.’ Coordinated searches with multiple active sonars can see into each other’s ‘shadow zones’ to cover an area more effectively. Also, having numerous sonar teams searching the same site increases detection recognition probability.

Continuous Active Sonar (CAS) is a constant cycle of a looping active transmission. This sonar is very capable in complex littoral or coastal waters, but lacks the extreme range that traditional complex sonar waveforms can achieve.

The Ticonderoga class guided missile cruiser USS Cowpens in dry dock in Japan. Note the bow-mounted AN/SQS-53B/C/D sonar., USN

Due to the high accuracy of CAS, a submarine should maintain as maximum a distance from the source as possible while keeping track of the CAS source. CAS is very easy for a submarine to localize because the active sonar will provide bearing changes over time with no gaps in transmission. This gives the trained submarine crew the CAS’s position within a few minutes of transmission.

The benefit of this kind of technique is that it requires a low-level of skill by the operator to conduct a successful search. If the sonar operator can locate the bright spot on a dark display, they can identify a detection. Artificial intelligence automatically marks these potential targets for further evaluation.

Another benefit of active sonar is that the submarine can be detected outside of its torpedo range. Early sonar detection shifts the initiative to the warship and removes the submarine’s primary advantage, an attack from concealment .

U.S. Navy Sonar Technicians inspect the locking bolt screws on a multi-functional towed array (MFTA) module during a MFTA retrieval aboard the Arleigh Burke class guided missile destroyer USS Mason ., USN

Modern active sonars have directional modes. These modes give the sonar coordinators flexibility in their sonar search plan. It is not uncommon to have multiple active platforms, in this case, surface combatants (warships), assigned to specific sectors around a high-value vessel, such as an aircraft carrier. This gives each sonar team a narrower search field, increasing the chance of detection, at the cost of a single point of failure.

Several disadvantages come with this sonar approach. Coordination between the active platforms is paramount when sonar searches overlap. This technique requires shared system timing, a “T-Zero,” and an accurate position of all transmitters so that they can plot the active propagation from another platform. Interfleet warfare system communication is a “Link”-type system that seamlessly integrates multiple sensors to help solve these coordination issues.

Typically, multiple active platforms operating in the same water space will use different modes to avoid interference and unnecessary confusion due to lack of proficiency or coordination. Navies that do not have this high-level of ship-to-ship integrated communication can conduct this type of search by manually triangulating detections.

Sonar Technicians stand watch in the sonar control room aboard the Arleigh Burke class guided-missile destroyer USS Jason Dunham . , USN

Triangulation is a simple method of using another platform’s sensor bearing (and range if you have it), knowing their position in relation to your own, and searching down that line of bearing. If you have contact, the tip of that triangle that crosses bearings is the submarine’s position. Manual triangulation was standard during the Cold War and is still employed today.

A disadvantage here is that the target submarine can hear the active sonar platform coming at least twice the distance that its active sonar will be able to detect the return. This is because a two-way propagation of the active signal is required. While the active sonar is waiting for the return, the target submarine has already received the initial transmission and can take action to minimize detection.

Passive sonar simply listens to noise as it passes the array. It collects sound signals and sorts them for the sonar operator by frequency and bearing. This helps the operator classify and track the position of the sound source.

Passive sonar search is a more refined, tactical, and skillful approach to submarine detection. Modern warship construction has given the surface navy an ability to quietly prowl the seas without the concerns of long-range passive counter detection. 21st-century versions of the “Prairie” and “Masker” systems can actively hide a ship’s broadband sound signature. New towed sonar arrays, and variable depth towed capability , gives surface sonars the ability to exploit tactical advantages previously only available to submarine sonars.

The combination of a quiet platform and low-frequency sonar arrays allows modern surface sonars to catch an unsuspecting submarine in open water. These passive methods are more time consuming as the area of uncertainty is always growing around a potential submerged target. Often, passive sonar will only receive a single transient sound on the bearing of a submarine. They mark a point at an estimated range often called the SWAG or ‘Sonar’s Wild Ass Guess,’ but it is officially called a ‘Datum.’

Datum is a point on the chart that slowly grows in uncertainty and distance over time. It is an expanding circle that ripples out in all directions like a splash on calm water. The speed at which the Area of Uncertainty (AoU) expands depends on the type of submarine. If it is a presumed Air-Independent Propulsion (AIP) submarine , the AoU grows slower than if it is suspected to be a faster nuclear sub.

A German-made Type 212 class submarine at periscope depth. , Public Domain

With no further information other than a single bearing of a suspected submarine, the Captain has a few options. They can maintain course and speed as not to alert the submarine that it has been detected while continuing to search. They can turn towards and pursue with active or passive sonars. The final option is turning away from the datum point and call for support if available.

If the commander has ASW helicopter capability, that will most likely be employed regardless of what other actions they take. The availability of long-range ASW aircraft like the P-8 Poseidon will be more effective in cost and capability than a helicopter and could be used instead. With submerged anti-air capabilities still in an early developmental phase, today’s airborne ASW hunters can search with near-immunity of being harmed by their target.

Airborne ASW Search Types

Airborne ASW begins with the datum point as its destination. As the datum expands, the helicopter races towards its center. The modern ASW helicopter is equipped with dipping sonar, sonar buoys, a magnetic anomaly detector, and torpedoes.

The first consideration is what loadout is best for the mission. Balancing fuel endurance with sensor loadout and attack capability must be configured before the task begins. A good rule of thumb is if the helicopter can get to the datum point within one hour, bring two weapons. Any longer, bring one torpedo and as much fuel as it can carry.

Once the helicopter is en route to the datum, the contact coordinator must factor in a few key variables: Submarine speed, the speed of the helicopter, sonar buoy detection range, time since detection, and finally, the time of the arrival at the datum.

Dipping sonar is the most cost-effective airborne sonar as it is not expended during a search. This makes it the most likely choice for the initial investigation. A dipping sonar will begin a series of spiral, non-disjointed dips around the center of the AoU.

A Seahawk helicopter using its dipping sonar. , USN

A non-disjointed sonar dip is a search technique that has a small amount of overlap from the previous submerged dipping sonar search area. This overlap compensates for the time it takes to reposition the dipping sonar from one search point to the next without the submarine slipping between the two searches.

A disjointed dipping pattern has no overlap and is more efficient, but it can allow a submarine to move through coverage gaps if not performed correctly. It is ideal to employ a pattern with enough overlap to compensate for the time between dips and target speed as the helicopter spirals out from the center of the AoU.

Sonar buoys (sonobuoys) give the searching platform a much better chance of detection because they stay in the water. They are not collocated every few minutes for a new search. The deploying asset does not need to remain with the deployed sensor; it can move on to the next search point, significantly increasing the chance of detection over dipping sonars because the AoU has less time to grow.

Sonobuoy search fields are only limited by the number of sonobuoys the helicopter can carry. You can read all about how an airborne sonobuoy search is executed in this past War Zone feature .

In many real-world encounters, the general direction of travel of the submarine is suspected. This could be due to topography and geographical limitations in coastal waters or additional information deduced after initial contact. If the general direction of submerged contact is known, the ASW assets can employ the “ 3-Ray search ” sonar search.

The center ray is the general direction of motion expected from the center of the AoU. Left and right rays are angled off-center according to the submarine’s expected speed; the higher the speed, the wider the angle between rays. Sonobuoys or dipping sonar is dropped on a vector at the estimated distance from the AoU center that matches the target speed.

The Nimitz class aircraft carrier USS Harry S. Truman and its escorts. Destroyers are often tasked with anti-submarine screening. , USN

The estimated speed is assumed based on the submarine type. Diesel submarines are expected to be slow and drop points will be near center AoU. AIP diesel submarines with energy cells are a little faster, and sonobuoys are dropped a little farther out to keep up. Nuclear submarines have the highest potential submerged speed, and the search field grows rapidly. The sonobuoy drop points are calculated on these basic estimates.

The 5-Ray search adds additional search vectors to each side of the 3-Ray model. This is required if the sonar search pattern is unable to keep up with the uncertainty of the target course. It covers a wider field, but takes longer to pursue, allowing the target to potentially escape. The specific angle between search vectors is determined by target speed and variables concerning the target course.

The Wedge Search is similar to the Ray Search models. The Wedge Search stays focused between two ray boundaries as it moves in the target’s expected direction. Instead of centering the sonobuoys or dipping sonar around a single line of bearing and crossing it left and right as in the Ray Search, each search area has two rays forming a wedge radiating out from the center of AoU. More effort and time are spent searching the center wedge; adjoining wedges are searched afterward. A Wedge search is suited for multiple ASW assets, but can also be conducted with a single asset.

With 18 sonobuoys and an eight-knot target less than an hour to datum, there is about a 33% chance of detection using these techniques if there are no oceanographic advantages the submarine can use , like high sea-state, a substantial layer, and topographical shadowing. Any additional factors like the target alertness, distance from AoU, and higher than expected submerged speed only reduce that chance even further.

Tom Clancy wrote, “It is wise to study the ways of one’s adversary” in his 1984 novel, The Hunt for Red October . The knowledge of these types of search models will help submariners avoid detection. Still, there is always the chance a single noise like a dropped tool or a hatch shutting may kick off a determined pursuit of your position.

A submarine must look for an indication of counter detection. Warships must slow from transit speeds to deploy helicopters. If a warship is maintaining a constant range or bearing, it is time for the submarine to reposition itself or to perform a covert evasion—moving away from the active sonar as quickly and quietly as possible.

South Korean sailors tour the sonar control room aboard the Arleigh Burke class destroyer USS McCampbell during an exercise. , USN

Successful Anti-Submarine Warfare (ASW) requires coordination, methodical execution, and patience. Modern sonar tools will not replace the operator’s instinct to identify and pursue suspicious detections. At sea, fleets are still defended by operators with headphones and tactical knowledge more so than artificial intelligence and algorithms. While there is a massive industry improving sensor technology, maintaining the at sea advantage relies heavily on improving the operator’s ability through better training and manpower retention.

This combination of technology and technique is how modern ASW warfare is conducted.

Aaron Amick is a retired U.S. Navy submarine sonarman. He served in both Atlantic and Pacific Oceans on 688 Los Angles class fast attack and Ohio class ballistic missile submarines. He has published two audiobooks on Cold War-era submarines, Akula SSN Project 971 Sub Brief and USS Nautilus SSN-571 Sub Brief . Now, Aaron manages a small Patreon page and contributes to The War Zone.

Contact the editor: Tyler@thedrive.com

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更新于美国东部时间2020年11月27日下午6:13。

反潜作战（ASW）是一项不断发展的实战，它不仅需要技巧和技术，更需要耐心和协调。如今海军使用的工具比冷战时期简单的声呐覆盖范围更广、功能更强大。人工智能有助于提醒操作人员注意潜在威胁。先进的海洋声波传播和射线追踪模型有助于在广阔的海域中规划高效的搜索行动。功率惊人的复杂声脉冲能够有效消除舰队面前的不确定性。

我们将在反潜作战环境中回顾潜艇搜索的基本原理，不是从另一艘潜艇的角度（你可以在这里阅读所有相关内容），而是从驱逐舰或其他具备反潜作战能力的舰艇的角度，在海面上巡航。

搜寻潜艇主要有两种基本方法：主动声呐搜索和被动声呐搜索。两种方法都有效，但各自的优势和劣势却截然不同。

最常见的搜索方式是全频谱主动声呐，它利用声能对船舶周围数万码范围内的水域进行探测。这些更新，或称“声呐脉冲”，间隔可达10-15秒。每次发射都会维持一个声波边界，当使用两个或多个声源（主动声呐）时，该边界几乎可以探测到所有目标。

单个主动声呐无法在海水等介质中均匀传播。它会因温度和密度的变化而发生弯曲，并像对待固体一样从热层反射。这会形成垂直的楔形盲区，称为“阴影区”。多个主动声呐协同搜索可以探测到彼此的“阴影区”，从而更有效地覆盖目标区域。此外，多个声呐小组同时搜索同一区域也能提高目标的探测识别率。

连续主动声呐（CAS）是一种循环往复的主动发射声呐。这种声呐在复杂的近岸或沿岸水域非常有效，但其探测距离不如传统复杂声呐波形那样远。

提康德罗加级导弹巡洋舰“考彭斯”号在日本干船坞中。请注意舰艏安装的AN/SQS-53B/C/D型声呐。（美国海军）

由于CAS的精度很高，潜艇应尽可能与CAS源保持最大距离，同时密切跟踪CAS源。潜艇很容易定位CAS，因为主动声呐会持续提供方位变化信息，传输无间断。这使得训练有素的潜艇艇员能够在CAS传输后几分钟内确定其位置。

这种技术的优势在于，它对操作人员的技能要求不高，即可成功进行搜索。声呐操作员只需在黑暗的显示屏上找到亮点，即可识别出目标。人工智能会自动标记这些潜在目标，以便进行进一步评估。

主动声呐的另一个优势在于，它可以探测到超出鱼雷射程的潜艇。早期声呐探测能够将主动权转移到军舰手中，并消除潜艇的主要优势——隐蔽攻击。

美国海军声纳技术人员在“阿利·伯克”级导弹驱逐舰“梅森”号上进行多功能拖曳阵列（MFTA）模块回收作业期间，检查该模块上的锁定螺栓。

现代主动声呐具有方向性模式。这些模式赋予声呐协调员在制定声呐搜索方案时更大的灵活性。通常情况下，会将多个主动声呐平台（例如水面作战舰艇）分配到高价值舰艇（例如航空母舰）周围的特定区域。这使得每个声呐小组的搜索范围更窄，提高了探测到目标的概率，但代价是存在一个单一故障点。

这种声呐方法存在一些缺点。当声呐搜索重叠时，各平台之间的协调至关重要。该技术需要共享系统时间、“T-Zero”以及所有发射器的精确位置，以便它们能够绘制来自其他平台的声波传播路径。舰队间作战系统通信是一种“链路”型系统，它能够无缝集成多个传感器，从而帮助解决这些协调问题。

通常情况下，在同一水域作业的多个作战平台会采用不同的通信模式，以避免因技术水平或协调性不足而造成干扰和不必要的混乱。缺乏这种高水平舰船间一体化通信能力的海军可以通过手动三角定位探测结果来进行此类搜索。

在阿利·伯克级导弹驱逐舰“杰森·邓纳姆”号上，声纳技师们在声纳控制室值班。

三角测量是一种简单的定位方法，它利用另一平台的传感器方位角（如果可以的话，还可以获取距离信息），了解其相对于自身的位置，然后沿着该方位角线进行搜索。如果与目标接触，则该三角形的交点即为潜艇的位置。手动三角测量在冷战时期是标准方法，至今仍在使用。

这种方法的缺点在于，目标潜艇至少可以在其主动声呐能够探测到回波的两倍距离外就听到主动声呐平台发出的信号。这是因为主动信号需要双向传播。当主动声呐等待回波时，目标潜艇已经接收到初始信号，并可以采取措施来降低被探测到的风险。

被动式声呐通过接收经过阵列的噪声信号来进行探测。它收集声信号，并按频率和方位角对信号进行分类，供声呐操作员使用。这有助于操作员对声源的位置进行分类和跟踪。

被动声呐搜索是一种更为精细、战术性更强、技巧性更高的潜艇探测方法。现代军舰建造技术使水面舰艇能够在无需担心远程被动反探测的情况下悄无声息地巡航。21世纪版本的“草原”（Prairie）和“掩体”（Masker）系统能够主动隐藏舰艇的宽带声学特征。新型拖曳式声呐阵列及其可变深度拖曳能力，使水面声呐能够利用以往只有潜艇声呐才能获得的战术优势。

现代水面声呐结合了静音平台和低频声呐阵列，能够在开阔水域探测到毫无防备的潜艇。这些被动探测方法较为耗时，因为潜在水下目标周围的不确定区域会不断扩大。通常，被动声呐只能接收到潜艇方位角上的一个瞬态声波。它们会在估计距离处标记一个点，这个点通常被称为SWAG（声呐的粗略估计），但其正式名称是“基准点”。

基准点是图表上的一个点，其不确定性和距离会随着时间推移而缓慢增加。它就像平静水面上的涟漪一样，向四面八方扩散。不确定区域（AoU）的扩张速度取决于潜艇的类型。如果是疑似采用不依赖空气推进（AIP）技术的潜艇，其AoU扩张速度会比疑似速度更快的核潜艇慢。

一艘德国制造的212型潜艇，处于潜望镜深度。（公共领域）

除了疑似潜艇的方位角之外，舰长没有任何其他信息，他有几种选择。他可以保持航向和航速，以免惊动潜艇，同时继续搜索。他也可以转向并使用主动或被动声呐进行追踪。最后一个选择是驶离基准点，并在有支援的情况下呼叫支援。

如果指挥官拥有反潜直升机能力，那么无论采取何种其他行动，它都极有可能被启用。像P-8“海神”这样的远程反潜飞机在成本和性能方面都比直升机更具优势，因此可以考虑使用。由于水下防空能力仍处于早期发展阶段，如今的空中反潜猎手几乎可以完全避免受到目标的伤害。

空中反潜搜索类型

空中反潜作战以基准点为目标。随着基准范围的扩大，直升机迅速向其中心飞去。现代反潜直升机配备了吊放式声呐、声呐浮标、磁异常探测器和鱼雷。

首先要考虑的是任务的最佳武器配置。必须在任务开始前平衡燃料续航能力、传感器配置和攻击能力。一个好的经验法则是：如果直升机能在1小时内到达目标点，则携带两件武器；如果时间更长，则携带一枚鱼雷和尽可能多的燃料。

一旦直升机前往基准点，联络协调员必须考虑几个关键变量：潜艇速度、直升机速度、声呐浮标探测范围、自探测以来的时间，以及最终到达基准点的时间。

吊放式声呐是最经济高效的机载声呐，因为它在搜索过程中不会消耗能量。这使其成为初步调查的最可能选择。吊放式声呐会围绕目标区域中心进行一系列螺旋状、连续的下沉扫描。

一架海鹰直升机正在使用其吊放式声呐。（美国海军）

非连续声呐俯仰是一种搜索技术，其搜索区域与前一次水下俯仰声呐搜索区域略有重叠。这种重叠可以弥补将俯仰声呐从一个搜索点重新定位到下一个搜索点所需的时间，避免潜艇在两次搜索之间发生偏移。

不连续的俯冲模式没有重叠区域，效率更高，但如果操作不当，潜艇可能会趁虚而入，穿过掩体盲区。理想的俯冲模式应具有足够的重叠区域，以补偿俯冲间隔时间和直升机从目标区域中心螺旋式飞出时的目标速度。

声呐浮标（声呐浮标）由于始终位于水中，因此能显著提高搜索平台的探测成功率。它们无需像吊放式声呐那样每隔几分钟就重新定位进行新的搜索。部署平台无需停留在已部署的传感器附近，可以移动到下一个搜索点，从而显著提高探测成功率，因为​​声呐探测区域（AoU）的扩展时间更短。

声呐浮标的搜索范围仅受直升机可携带的声呐浮标数量限制。您可以在之前的《战区》专题文章中了解空中声呐浮标搜索的详细操作方法。

在许多实际遭遇战中，通常只能大致判断潜艇的行进方向。这可能是由于沿海水域的地形和地理限制，也可能是由于初次接触后推断出的其他信息。如果已知水下目标的大致行进方向，反潜作战力量就可以采用“三射线搜索”声呐进行搜索。

中心射线代表从目标区域中心预期的大致运动方向。左右射线根据潜艇的预期速度偏离中心成一定角度；速度越高，射线之间的角度越大。声呐浮标或吊放式声呐会按照与目标速度相匹配的矢量，以距离目标区域中心估计距离的方式投放。

尼米兹级航空母舰“哈里·S·杜鲁门”号及其护航舰艇。驱逐舰通常负责反潜护航任务。

估算速度是基于潜艇类型而定的。柴电潜艇预计速度较慢，投放点将靠近AoU中心。配备能量电池的AIP柴电潜艇速度稍快，为了跟上其速度，声呐浮标的投放点会稍远一些。核潜艇的潜在水下速度最高，搜索范围也迅速扩大。声呐浮标的投放点是根据这些基本估算值计算的。

五射线搜索在三射线模型的两侧各增加了一个搜索矢量。当声呐搜索模式无法跟上目标航向的不确定性时，就需要采用这种方法。五射线搜索覆盖范围更广，但追踪时间更长，这可能导致目标逃脱。搜索矢量之间的具体角度取决于目标速度和与目标航向相关的变量。

楔形搜索与射线搜索类似。楔形搜索在沿目标预期方向移动时，始终聚焦于两条射线边界之间。与射线搜索将声呐浮标或吊放声呐围绕单一方位线并左右交叉不同，楔形搜索的每个搜索区域都由两条射线组成，形成一个从目标区域中心向外辐射的楔形。搜索中心楔形区域会耗费更多的时间和精力；相邻的楔形区域随后进行搜索。楔形搜索适用于多艘反潜舰艇协同作战，但也可使用单艘舰艇执行。

如果潜艇没有可以利用的海洋学优势（例如高海况、厚水层和地形阴影），且目标航速为8节，距离目标点不到一小时，那么使用18个声呐浮标探测到目标的概率约为33%。目标警戒性、与目标点的距离以及高于预期的水下航速等其他因素只会进一步降低探测概率。

汤姆·克兰西在其1984年的小说《猎杀红色十月》中写道：“研究对手的行事方式是明智之举。” 了解这类搜索模式有助于潜艇兵避免被发现。然而，即使是工具掉落或舱门关闭这样的小小声响，也可能引发敌方对你位置的严密追击。

潜艇必须时刻警惕反探测的迹象。军舰必须减速才能部署直升机。如果军舰保持恒定的距离或方位，潜艇就应该重新调整位置或进行隐蔽规避——尽可能快速、安静地远离主动声呐探测范围。

在一次演习中，韩国水兵参观了阿利·伯克级驱逐舰“麦坎贝尔”号上的声呐控制室。

成功的反潜作战需要协调配合、有条不紊的执行和耐心。现代声呐工具无法取代操作员识别和追踪可疑目标的本能。在海上，舰队的防御仍然更多地依赖于佩戴耳机、具备战术知识的操作员，而非人工智能和算法。尽管传感器技术正蓬勃发展，但保持海上优势的关键在于通过更好的培训和人员留任来提升操作员的能力。

现代反潜战就是通过这种技术与战术的结合来进行的。

亚伦·阿米克是美国海军退役潜艇声纳兵。他曾在大西洋和太平洋服役，先后在洛杉矶级快速攻击潜艇（688型）和俄亥俄级弹道导弹潜艇上服役。他出版了两本关于冷战时期潜艇的有声读物：《阿库拉号核潜艇971项目简报》和《鹦鹉螺号核潜艇571项目简报》。如今，亚伦运营着一个小型Patreon页面，并为《战区》网站撰稿。

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