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PTSD & Nexus Letters · Sea Service

PTSD From Submarine Service: Collisions, Flooding, Fires, and VA Nexus Letters

A submariner does not need to have gone down with a boat to carry a Criterion A stressor. What distinguishes submarine trauma is not the size of the casualty but the fact that there is nowhere to go while it is happening.
A submarine running on the surface in open ocean

Written by Jessica R. Allen, M.D., licensed psychiatrist and former VA Compensation and Pension examiner | Brightview Psychiatry Solutions PLLC

Dr. Jessica R. Allen

Summary

A submarine veteran can meet DSM-5-TR Criterion A without having survived a famous disaster and without anyone having died. Criterion A is satisfied by exposure to threatened death or serious injury, which a flooding casualty, fire, grounding, collision, or loss of depth control can produce even when the boat is recovered and the crew comes through physically intact.

What distinguishes submarine trauma is the impossibility of escape. During a casualty the crew remains sealed inside a pressure vessel at depth, unable to leave, performing technical work while the outcome stays in doubt. Confinement, loss of individual control, sustained uncertainty, and perceived imminent death occur together and persist for minutes to hours.

Qualifying stressors

Flooding, fire in a sealed atmosphere, loss of propulsion or electrical power, uncontrolled depth excursions, emergency blows under genuine emergency conditions, collisions and groundings, torpedo or battery-well emergencies, witnessing serious injury or death of a shipmate, and physical or sexual assault aboard the boat.

Characteristic later symptoms

Claustrophobia and intolerance of windowless rooms, compulsive identification of exits, exaggerated startle to alarms, hypervigilance to mechanical sound, nightmares of sinking or flooding, panic in elevators and aircraft, checking behaviors, and avoidance of water and boats.

Evidentiary standard

Service connection under 38 C.F.R. § 3.304(f) requires a conforming diagnosis, credible supporting evidence that the stressor occurred, and a medical nexus. The relaxed standard at § 3.304(f)(3) applies only to fear of hostile military or terrorist activity, so a peacetime submarine casualty ordinarily does require corroboration — typically available through deck logs, command investigations, personnel records, and Navy releases.

What a nexus letter adds

Treatment records establish that a diagnosis exists but rarely address where the condition came from, because etiology is not what a progress note is for. An independent medical opinion fills that gap: it identifies the stressor, explains the mechanism linking it to current symptoms, addresses alternative explanations, and states the conclusion under the governing standard — at least as likely as not, a 50 percent probability or greater. It cannot supply evidence that the stressor occurred or determine the outcome of a claim.

What makes a nexus opinion persuasive

Under Nieves-Rodriguez v. Peake, 22 Vet. App. 295 (2008), probative weight turns on the stated reasoning rather than the author's credentials. An opinion should make the escape-impossibility mechanism explicit rather than assuming a reviewer understands it.

Most discussion of submarine casualties is written as naval history: the hull damage, the investigation, the officers relieved. Very little of it is written as psychiatry. That gap matters for veterans, because the features that make a submarine casualty survivable are not the same features that make it psychologically survivable. A crew can do everything right, bring a damaged boat home, and still carry the encoding of the hours in between.

This article addresses how submarine service produces a recognizable trauma signature, how that signature shows up years later in symptoms that are frequently misread as unrelated anxiety or claustrophobia, and what an independent medical opinion should address when a submarine veteran files a VA claim for posttraumatic stress disorder.

Does a Submariner Need to Have Survived a Famous Disaster to Have a Criterion A Stressor?

No. The diagnostic threshold under DSM-5-TR is exposure to actual or threatened death, serious injury, or sexual violence — through direct experience, witnessing it in person, learning that it happened to a close associate, or repeated exposure to aversive details. Nothing in that definition requires that the event become publicly known, that a boat be lost, or that anyone die. Events aboard submarines that can meet Criterion A include:

That last item deserves emphasis. Criterion A includes threatened death. The determinative question is not whether the boat was in fact going to sink. It is whether, at the time, the veteran was confronted with circumstances that involved a credible threat of death or serious injury. Submariners are trained to read casualty indications accurately. A veteran who understood exactly what a flooding alarm at depth meant may have been in greater subjective danger, not less, than a shipmate who did not.

In practice

The most common thing I hear from submarine veterans is some version of minimization. “It wasn't combat.” “We got the boat home.” “Nobody made a big deal out of it.” Clinically, those statements tell me almost nothing. They describe the outcome, not the exposure.

What I need to know is where the veteran was standing, what the indications were, what he understood those indications to mean, what he was required to do while he understood it, and how long the interval ran before anyone knew the boat would come up. Two sailors on the same watch can give me nearly identical accounts of an event and have had entirely different exposures.

Why Does Confinement Inside a Submerged Pressure Vessel Intensify Traumatic Encoding?

This is the clinical heart of the matter, and the part most often missing from nexus letters written without sea service familiarity.

In nearly every other military trauma context, escape is at least theoretically available. A soldier under fire can move to cover; a sailor on a surface ship can, in the last instance, abandon ship; an airman can eject. Those options may be poor or unavailable in practice, but the nervous system registers their existence. On a submerged submarine the option does not exist in any form — no door, no surface to reach, no rescue within any relevant timeframe.

Threat response is organized around action, and when neither fight nor flight is available the system does not simply stand down: sustained, inescapable threat is associated with tonic immobility and dissociation, a pairing of high arousal with enforced motionlessness that yields more fragmented and more intrusive encoding.

The clinical distinction

Four conditions converge inside a submerged hull during a casualty: total physical confinement, complete loss of control over the outcome, profound uncertainty about whether the boat will recover, and the perception of imminent death. Each is independently associated with more severe traumatic encoding. Submarine casualties impose all four at once, and sustain them for minutes to hours rather than seconds.

Submariners are also not passive during a casualty. They are drilled to perform precise, high-stakes work while the outcome remains in doubt — fighting flooding, plotting a course, treating an injured shipmate in the same interval in which they believed they were going to die. The trauma is encoded alongside the performance, not instead of it, which is why submarine veterans so often narrate the event flatly and are then judged, wrongly, to be minimally affected.

In practice

Submariners are among the flattest historians I take. A veteran will describe a flooding casualty in the register he would use for a drill — sequence, actions, times — and stop. The affect is not absent; it is sequestered behind the procedure. When I ask what he thought was going to happen, there is usually a pause, and what follows is not procedural at all. An examiner who never asks will document a competent sailor recounting a technical event — a materially incomplete record of what occurred.

What Submarine Incidents Illustrate These Stressors?

The following incidents are documented in public Navy releases, command investigations, and contemporaneous reporting. They are included as illustrations of the categories of casualty that produce Criterion A exposure — not as the only qualifying events, and not because a veteran must have been aboard one of these boats to have a valid claim.

Documented U.S. submarine casualties with surviving crews

USS San Francisco (SSN-711)

8 January 2005

Struck an uncharted seamount at flank speed at a depth of 525 feet, roughly 360 nautical miles southeast of Guam. The bow and forward ballast tanks were severely damaged. Ninety-eight crewmen were injured; Machinist's Mate 2nd Class Joseph Allen Ashley, 24, died of head injuries the following day. Because the forward tanks were ruptured, the emergency blow initially vented air into the sea, and the crew struggled for positive buoyancy before surfacing and returning the boat to Guam.

The most complete illustration available: sudden catastrophic impact, injuries throughout the crew, a shipmate's death, degraded ability to surface, and prolonged uncertainty aboard a badly damaged boat. Survivable, and severely traumatic.

USS Connecticut (SSN-22)

2 October 2021

Grounded on an uncharted seamount while operating submerged in the South China Sea. Eleven crew members were injured. The nuclear propulsion plant was unaffected and the boat transited on the surface to Guam. The command investigation attributed the grounding to an accumulation of errors in navigation planning, watchteam execution, and risk management.

Demonstrates that a violent, unexplained collision while fully submerged is psychologically significant even when injuries are characterized as minor and the boat remains stable. For the crew, the object was unidentified at the moment of impact.

USS Hartford (SSN-768)

20 March 2009

Collided with the amphibious transport dock USS New Orleans (LPD-18) at approximately 0100 in the Strait of Hormuz while at periscope depth. The collision rolled Hartford roughly 85 degrees to port. Fifteen sailors aboard the submarine were injured; the sail, periscope, and port bow plane were damaged.

An 85-degree roll in a confined interior at one in the morning is a violent, disorienting bodily event. Illustrates how high operational tempo, fatigue, restricted navigation, collision alarms, and uncertainty about damage combine even when the boat survives intact.

USS Greeneville (SSN-772)

9 February 2001

While performing an emergency main ballast tank blow demonstration about nine nautical miles south of Oahu, surfaced beneath the Japanese fisheries training vessel Ehime Maru. The Ehime Maru sank within roughly ten minutes. Nine of the thirty-five people aboard were killed: four high school students, two teachers, and three crew. Rough seas and the submarine's low trim after the blow prevented the crew from taking survivors aboard.

Trauma need not arise from fear of one's own death. Witnessing or participating in an event that killed others, being unable to render aid while survivors were visible in the water, survivor guilt, and moral injury are all implicated here.

How Do the Thresher and Scorpion Losses Shape the Environment Aboard Later Boats?

USS Thresher (SSN-593) was lost on 10 April 1963 during deep-dive trials off Cape Cod. All 129 aboard died, including civilian shipyard personnel. USS Scorpion (SSN-589) was lost on 22 May 1968 en route to Norfolk, southwest of the Azores, with 99 aboard. Neither boat had survivors, so neither functions as a case study in survivor psychopathology.

They are nonetheless directly relevant, because they define the psychological environment in which every subsequent American submariner has served. These losses are not obscure history within the submarine force. They are taught, memorialized, and understood. The SUBSAFE program exists because of Thresher. Every submariner knows that a submarine casualty can end with the loss of the entire boat and that meaningful rescue from depth is, in practical terms, unavailable.

Why this matters to a claim

A veteran's appraisal of danger is part of the traumatic exposure, not background color. When a submariner heard a flooding alarm at depth, he was not making an abstract guess about his odds. He was drawing on institutional knowledge of exactly how such events had ended before. This is why a casualty that a reviewer might characterize as minor can produce a full traumatic response in a trained submariner, and why an examiner unfamiliar with the submarine force may substantially underestimate the severity of the exposure.

What Symptoms Commonly Follow Submarine Trauma?

Submarine-related PTSD frequently presents with a symptom pattern that maps onto the physical conditions of the original event. The conditioned stimuli are the sensory features of life inside the hull: enclosure, mechanical noise, alarms, and the absence of an exit.

Enclosure and exit

Claustrophobia; intolerance of closed doors, windowless rooms, MRI scanners, and basements; a compulsion to identify exits on entering any space; refusal to sit away from a door; panic in elevators and on aircraft.

Sound and alarm

Hypervigilance to mechanical and HVAC sounds; exaggerated startle to alarms, klaxons, and smoke detectors; distress at changes in pitch or pressure; monitoring of background noise for anomalies.

Sleep

Insomnia; nightmares involving sinking, flooding, drowning, or being unable to reach a hatch; nocturnal panic; sleep-onset difficulty tied to the loss of situational awareness while asleep.

Checking and control

Repetitive checking of doors, locks, gauges, and systems; difficulty delegating; distress when unable to verify that equipment is functioning; intolerance of being a passenger.

Avoidance

Avoidance of water, boats, swimming, diving, and bridges; avoidance of reunions and of contact with former shipmates; refusal to discuss the casualty; avoidance of documentaries or news involving submarines.

Mood and cognition

Survivor guilt; persistent negative beliefs about having failed to prevent or respond adequately; moral injury where others died; emotional numbing; detachment from family described as beginning after the event.

Two clinical cautions follow. First, these symptoms are commonly diagnosed elsewhere as generalized anxiety, panic disorder, specific phobia, or obsessive-compulsive disorder — sometimes for decades — without the traumatic origin ever being identified, because no one asked what the veteran did for a living at twenty-two. Second, avoidance is itself a diagnostic criterion, which means the veterans with the most severe presentations are often the least likely to have generated a treatment record. The absence of contemporaneous complaints is not evidence that the condition was absent.

In practice

One thing I ask about specifically is where the veteran sits — in a restaurant, in a waiting room, in my office. Veterans who have never connected a single symptom to their service will still, thirty years on, take the chair nearest the door and be able to tell me how many exits the room has without looking up.

They almost always describe it as a preference. It is rarely a preference. It is a conditioned response to having spent a portion of their twenties somewhere that had no exit at all, and it is frequently the first symptom a veteran will acknowledge, because it does not feel like a symptom.

Can PTSD Arise From Witnessing a Casualty Rather Than Fearing One's Own Death?

Yes, and the Greeneville case makes the point clearly. The submarine itself sustained comparatively minor damage and its crew was never in danger of loss. But nine people died as a direct result of a maneuver the crew executed, survivors were visible in the water, and the crew was unable to bring them aboard because of sea state and the boat's trim after the emergency blow.

DSM-5-TR expressly contemplates traumatic exposure through witnessing an event in person. Beyond the diagnostic criteria, this scenario implicates moral injury — the psychological consequence of participating in, or failing to prevent, an outcome that violates deeply held moral commitments. Moral injury is not itself a DSM diagnosis, but it frequently co-occurs with PTSD, shapes the clinical picture, and is directly relevant to the persistent negative beliefs and self-blame described in Criterion D.

How Does VA Evaluate a Submarine-Related Stressor?

Service connection for PTSD under 38 C.F.R. § 3.304(f) requires three elements: a diagnosis of PTSD conforming to the criteria in 38 C.F.R. § 4.125, credible supporting evidence that the claimed in-service stressor occurred, and medical evidence of a causal nexus between current symptoms and the claimed stressor.

The second element is where submarine claims most often need attention, and there is a point here that is easy to get wrong. The relaxed evidentiary standard at § 3.304(f)(3), which allows lay testimony alone to establish a stressor, applies to stressors related to fear of hostile military or terrorist activity. A peacetime collision, grounding, fire, or flooding casualty is not hostile activity. Most submarine casualty claims therefore fall under the general rule and do require credible supporting evidence that the event occurred.

The practical consequence

This is less burdensome than it sounds. Major submarine casualties are among the best-documented events in military service. Command investigations, Navy news releases, ship's deck logs, personnel records placing the veteran aboard on the date in question, award citations, medical records of injuries sustained, and contemporaneous news coverage all exist. The evidentiary task is usually one of assembly rather than reconstruction. Separate provisions at § 3.304(f)(5) permit corroboration from sources other than service records where the stressor was a personal assault, including an assault that occurred aboard ship.

A nexus opinion cannot supply the stressor evidence — that is a factual matter for the record and the adjudicator. What the opinion does is establish that the documented event is adequate to support the diagnosis, that the veteran's current symptoms are attributable to it, and that competing explanations have been considered and addressed.

What Does a PTSD Nexus Letter Actually Do?

A nexus letter — more precisely, an independent medical opinion — is a written medical opinion addressing whether a veteran's current condition is related to service. It exists to satisfy the third element of § 3.304(f): medical evidence of a causal link between present symptoms and the in-service stressor.

That element is the one most often left unaddressed, and the reason is structural rather than anyone's fault. Treating clinicians document what they are treating. A VA or community progress note saying “PTSD, stable on sertraline, continue therapy” establishes that a diagnosis exists. It says nothing about where the condition came from, because etiology is not what a treatment note is for. A veteran can accumulate years of records that thoroughly document the disorder and never once address its origin in the language the adjudication requires.

A well-constructed opinion fills that specific gap. It states a diagnosis conforming to the criteria required under 38 C.F.R. § 4.125, identifies the stressor, explains the mechanism connecting it to the veteran's current symptoms, and reaches a conclusion under the governing standard — at least as likely as not, meaning a 50 percent probability or greater, which is a materially lower threshold than medical certainty.

That standard deserves a moment. Clinicians are trained to be cautious about causal claims and often hesitate to write anything stronger than “may be related.” But the question VA asks is not whether service caused the condition beyond doubt. It is whether the evidence for and against is at least in equipoise. An opinion that reaches the correct standard and explains its reasoning is doing ordinary clinical work, not overstating.

From the examiner's side

Having conducted compensation and pension examinations, I would add a practical observation about why these opinions matter. A C&P examiner works within a fixed appointment, from the record in front of them, and often without any frame of reference for what a particular event involved. The word “grounding” in a service record does not, on its face, convey a crew fighting for positive buoyancy at five hundred feet with the forward tanks ruptured.

If the veteran narrates that event flatly — and submariners generally do — and the examiner has no background against which to hear it, the exposure can end up recorded as minor. In my experience that is rarely bad faith. It is a mismatch between the time available and what the event actually was. An independent opinion is an opportunity to put the event back in proportion, with the reasoning shown.

It is equally important to be clear about what an opinion cannot do. It cannot supply evidence that the stressor occurred; that remains a factual question for the record and the adjudicator. It cannot override contradictory evidence, manufacture a diagnosis the clinical picture does not support, or determine the outcome of a claim. VA weighs it alongside everything else in the file.

An independent opinion tends to add the most where the nexus element is genuinely undeveloped: where a C&P examination reached an unfavorable conclusion whose reasoning can be engaged directly, where a long gap in treatment records needs to be explained rather than left to speak for itself, where a secondary condition depends on a mechanism nobody has articulated, or where service ended decades ago and the connection between then and now has never been set out by a physician.

What Should a Nexus Letter for Submarine-Related PTSD Address?

A useful independent medical opinion in these cases does more than recite the criteria. It should:

  1. Identify the stressor with specificity — the boat, the hull number, the date, the veteran's watch station and physical location within the boat, the depth, and what the veteran was doing during the casualty.
  2. Explain the escape-impossibility feature explicitly. A reviewer who has not served aboard a submarine may not appreciate why a survivable casualty produced a severe traumatic response. The opinion should make the mechanism explicit rather than assuming it is understood.
  3. Map each symptom cluster to the DSM-5-TR criteria and, where possible, to the sensory features of the original event — connecting present-day intolerance of windowless rooms to the compartment the veteran occupied, for example.
  4. Address the gap in treatment records where one exists, explaining avoidance as a diagnostic feature rather than leaving the silence to be read as absence of illness.
  5. Consider and address alternative etiologies rather than ignoring them, including any pre-service history, so the opinion survives scrutiny.
  6. State causation and aggravation as separate theories where the record supports both, and state the conclusion under the correct standard: at least as likely as not, meaning a 50 percent probability or greater.

Under Nieves-Rodriguez v. Peake, 22 Vet. App. 295 (2008), the probative weight of a medical opinion turns on the reasoning that supports its conclusion, not on the credentials of its author or the volume of records reviewed. An opinion that states a conclusion without explaining the mechanism carries little weight regardless of who signed it. This is why the confinement analysis matters practically and not merely descriptively.

Frequently Asked Questions

Can a submariner claim PTSD if no one was killed or seriously injured?

Yes. Criterion A is met by exposure to threatened death or serious injury, not only actual death or injury. A flooding casualty, fire, or loss of depth control during which the veteran reasonably believed the boat might be lost can satisfy the criterion even though the crew came through without physical harm.

Does the incident have to appear in the veteran's service treatment records?

No. The stressor must be corroborated by credible supporting evidence, but that evidence need not come from medical records. Deck logs, command investigations, personnel records establishing presence aboard, Navy releases, award citations, and buddy statements can all serve. Many submariners never sought care during service, and a service treatment record silent as to psychiatric complaints does not by itself defeat a claim.

What if the veteran cannot discuss details of a classified patrol?

Classification restricts the operational details a veteran may disclose — the mission, the location, the target. It does not usually prevent description of the nature of a casualty, the veteran's own experience, or the resulting symptoms. A stressor statement can be drafted to convey what is necessary for the claim while respecting security obligations, and the veteran should not disclose classified information in the course of filing.

Is claustrophobia by itself enough to support a PTSD claim?

Claustrophobia alone is a specific phobia, not PTSD. It becomes part of a PTSD presentation when it arose after an identified traumatic event and appears alongside the other required criteria — intrusion symptoms, avoidance, negative alterations in cognition and mood, and alterations in arousal and reactivity. The clinical question is whether the fear of enclosure is a conditioned response to the casualty or a longstanding independent trait, which is why a careful pre-service history matters.

Can a veteran who served decades ago still file?

Yes. There is no time limit for filing a claim for service connection. Delayed presentation is common in this population, and avoidance of reminders is itself a diagnostic criterion. The evidentiary task is establishing the in-service stressor and the nexus, which does not become impossible with the passage of time — though records assembly generally takes longer.

If a veteran is already being treated for PTSD at VA, is a nexus letter still useful?

Often, yes. Treatment records establish that the condition exists and document its severity, but they usually do not address causation, because that is not the purpose of a progress note. Service connection requires medical evidence linking the current condition to an in-service stressor, stated under the applicable standard. Where that link has not been articulated anywhere in the file, an independent opinion addresses the element that treatment records leave open.

What if a prior C&P examiner concluded the stressor was insufficient?

An examiner's conclusion is evidence, not a final determination, and it can be addressed by a subsequent opinion that engages with its reasoning. Where an examiner appears to have treated a casualty as minor because the boat survived, an independent opinion can explain why that reasoning does not account for the conditions of confinement and perceived threat at the time of the event.

About the author

Jessica R. Allen, M.D. is a licensed psychiatrist and former VA Compensation and Pension examiner who also served as a Social Security disability examiner. She completed medical school at Eastern Virginia Medical School, psychiatry residency at East Carolina University, and an addiction psychiatry fellowship at the Medical University of South Carolina. Through Brightview Psychiatry Solutions PLLC in Wake Forest, North Carolina, she prepares independent medical opinions and nexus letters for veterans pursuing VA disability claims nationwide.

Sources

Related Reading

If you are in crisis, the Veterans Crisis Line is available 24/7: dial 988 and press 1, or text 838255. This article is general information about VA claims and nexus letters, not medical advice, and it does not create a treatment relationship.

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