Homicidal Cut Throat: The Forensic Perspective

1 Senior Lecturer, Department of Forensic Medicine, Faculty of Medical Sciences, University of Sri Jayewardenepura, Sri Lanka.

Jeewana C Samaraweera

2 Acting Consultant Judicial Medical Officer, District General Hospital, Vavuniya, Sri Lanka.

1 Senior Lecturer, Department of Forensic Medicine, Faculty of Medical Sciences, University of Sri Jayewardenepura, Sri Lanka.

NAME, ADDRESS, E-MAIL ID OF THE CORRESPONDING AUTHOR: Dr. Muditha Vidanapathirana, Senior Lecturer, Department of Forensic Medicine, Faculty of Medical Sciences, University of Sri Jayewardenepura, Gangodawila, Nugegoda, Sri Lanka. E-mail: moc.liamg@anadivahtdidum, kl.ca.pjs@anadivahtidum

Abstract

The forensic pathologists have a challenging task during the ascertainment of the manner of death in cut throat injuries when presented with no proper history or witnesses. We report a rare homicide, where a person was killed by the father of his gay partner. A 51-year-old married man was found dead in his car on the driving seat at a road. There were blood stains on the dash board and windscreen. No weapon had been recovered. At autopsy, a deep, oblique, long incised injury was found on the front of the neck. There were no hesitant or defense injuries. The cause of death was cut throat. The findings were compatible with a homicidal cut throat by a right handed person from behind after head being restrained firmly. Findings were compatible with the history provided by the suspect.

Case Report

A 51-year-old married man was found dead in his car on the driving seat at a busy roadway around 1.30 p.m. He had been a right handed person.

No weapon had been recovered from the vehicle or at the scene. On examination, there was lot of blood and blood stains in the vehicle including the dashboard and the windscreen.

The initial post-mortem investigation revealed no suspect. At the autopsy, the clothes showed vertical distribution of blood [ Table/Fig-1 ]. A deep, obliquely placed, long incised neck injury was found on the front side of the neck. The left end of the injury started below the ear at upper third of the neck and deepened gradually with severance of the left carotid artery. The right sided end of the injury was at the mid third of the neck with a tail abrasion [ Table/Fig-2 ].

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Clothes showed vetical distribtion of blood stains and the left end of the cut throat started just below the ear.

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Cut throat from right side.

There were no other injuries including hesitant cuts or defense injuries. Lungs showed aspiration of blood. Deceased’s blood was negative for alcohol. There was no evidence such as frothy blood or air emboli in right ventricle to suggest air embolism. Postmortem X-ray of the chest for the detection of air in the venous system and heart was not done due to technical constraints. Cause of death was cut throat.

Later, the suspect was produced, and he was the father of the deceased’s gay partner. The suspect and his son had got into the deceased’s car to request him to terminate this relationship, because the son did not consent for an arranged marriage. The suspect had been in the rear seat right behind the deceased and the son had been the front seat passenger. When the deceased disagreed to terminate the relationship, father of the gay partner had cut the throat of the deceased using a knife and both had escaped. The suspect was a right handed person.

Discussion

Cut throats can be homicidal, suicidal or accidental [1]. Homicidal cut-throats are a well-recognized method of killing while suicidal cut throats are less commonly reported and accidental cut throats are rare [2]. The forensic pathologists have a challenging and important task when ascertaining the manner of death when cut throats are presented with no proper history or witnesses [3]. It was highlighted in the OJ Simpson case too, where the body of OJ Simpson’s ex-wife, Nicole was found dead with her throat cut [4].

Emotionally driven murders are committed by mothers in neonaticides [5], intimate partners of hetero or homosexual relationships, etc. Further, killing of a gay partner by the other partner has been reported in literature due to different reasons such as attempting to terminate the relationship, initiate a relationship with another partner, etc. However, the case under discussion is a rare homicidal cut throat where the perpetrator was the father of the gay partner.

Accidental cut throats are exceptionally rare. They are usually seen only when a victim goes through a sheet of glass or is struck in the neck by a sharp-edged missile or flying piece of glass [6]. In this case, there was no evidence of the vehicle being met with an accident to sustain such a cut throat injury.

The suicidal cut throat wound is similar to the homicidal cut throat from behind. The wound usually begins higher on the neck on the side opposite to where it terminates [6]. Since the deceased was a right handed person, the suicide cut throat should typically start from upper third of the left side of the neck and be ended at a point lower than the origin on the right side as was found in this case.

Suicidal cut throats are usually, but not always, accompanied by hesitation marks [6]. In this case, no such hesitation injuries were found. Further, a fatal suicidal cut throat may be accompanied by cadaveric spasm with the knife found firmly clenched in the victim’s hand. According to the investigation findings, even a weapon was not found at the scene. Further, there were no self-inflicted injuries or scars such as multiple, parallel and superficial injuries in accessible sites according to dexterity of the deceased [7]. When the history, autopsy findings and scene findings are considered the suicidal cut throat could be safely excluded.

Homicidal cut throats can be produced in two different ways; depending on whether they are produced from the back or the front [4]. Of those two methods, cutting a person’s throat from behind is the most common. The head is pulled back, and the knife is then drawn across it. The knife is drawn across the neck, from left to right by a right-handed assailant and from right to left by a left-handed individual [6]. The wound inflicted deepening at the beginning and then tails off at the opposite side of the neck [8]. The gradually deepening left end should be the beginning [8] of the cut throat and was reconfirmed by the tail abrasion found at the right end. Therefore, the direction of this cut throat should be left to right.

The homicidal cut throat injuries inflicted from behind are usually longer. They usually starts below the ear, runs obliquely downward and medially, then straight across the midline of the neck, and ends on the opposite side of the neck, lower than its point of origination [6]. Therefore, in this case, the neck incision was compatible with a cut throat from behind by a right handed person.

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Contrary to that, the homicidal cut throats inflicted from the front tend to be short and angled. Horizontal wounds inflicted from the front are the least common [6]. Further, instead of the neck being cut with one long, continuous motion, these wounds are inflicted by several swipes or slashes [6] and such short injuries were not found in this case. Therefore, homicidal cut throat inflicted from the front side can be safely excluded.

It was noticeable that the deep cut throat found in this case was a single incision without surrounding injuries. Multiple, parallel, superficial cuts found above and below the deep fatal cut in homicides suggest that the deceased attempted to get away, his head was not sufficiently immobilized by restrain and he was intoxicated or tortured [8]. In this case, the alcohol level was negative and there were no such superficial cuts. Presence of single deep cut suggested that the deceased’s head would have been restrained firmly.

Presence of blood stains on the windscreen and dash board of the vehicle further confirmed that it was a deep cut severing the arteries resulting blood spray front of the victim. The vertical distribution of the blood stains re-confirmed the seated position of the deceased in the vehicle at the time of the infliction of injuries.

There was no evidence of mutilation or emotionally driven injuries. Emotionally motivated killings occur in jealousy, intense hatred and in sexual overtones. Further, they show evidence of overkill or rapid stabs and are indicated by multiple, parallel, uniformly deep stabs, grouped in one area of the body with or without mutilation [8]. The killing method used in homicides may reflect the motivation of the offender and qualities of the victim-offender relationship [9], however, such emotionally driven injuries were not found in this case. Absence of such injuries could be important to assess the reliability of the suspect’s claim for the murder rather than his son, the gay partner of the deceased.

At autopsy, there was no evidence of air embolism such as frothy blood or air emboli in right ventricle. Mechanisms of death in this case were blood loss and aspiration of blood following the cut throat.

The length of time it takes to die following an incised wound of the neck depends on several factors. They include whether the venous or arterial systems are severed and whether there is air embolism [6]. In some instances, victims with single carotid artery cut have moved for about 10 minutes [10].

Conclusion

The homicidal pathologists have to assess all the possibilities voicing their adjudgment. As, in this case, the possibilities of the homicidal cut throat injuries inflicted from behind were analysed. With the presence of evidence of spurting and massive haemorrhage, a prolong survival was highly unlikely and the deceased could have survived most probably seconds or minutes.

Dive Speak: Learn Scuba Diving Terms, Phrases and Slang

Dive hand signals

Be in the know with this list of scuba diving words, terms, phrases and slang.

Scuba Diving Terms and Phrases: A

Advanced Open Water: Follow up certification after Open-Water Diver; allows for deeper

Air: A gas mixture containing 21percent oxygen, 78 percent nitrogen, and 1 percent other gasses (mainly argon); compressed air is held in a tank for scuba diving.

Apnea: Breath-holding; apnea diving is a type of freediving, but in scuba diving you should never hold your breath.

Ascent: Rising to the surface when diving; typically at the end of a dive.

Ascent Rate: How quickly a diver returns to the surface. You should never ascend faster than your bubbles as a safety precaution.

Scuba Diving Terms and Phrases: B

Backroll: Entering the water from the side of the boat, back first.

BC/BCD: Buoyancy Compensator. This is the harness divers wear that hold the air tank and connects to the regulator.

Bends/Bent: The pain a diver feels when suffering from Decompression Sickness (DCS). See DCS definition below. The bends often occur from ascending too quickly.

Boat Dive: Scuba diving that requires a boat ride to the dive site.

Bootie: Scuba gear divers wear with open-heel fins. Booties can range from thin (1 mm or less) to thick (7 mm) neoprene and protect your feet from the cold as well as sharp rocks and other hazardous things you could step on when shore diving.

Bottom Time: The length of your dive.

Buddy: The person you dive with; this is the person you discuss a dive plan with and you are both responsible for keeping each other safe.

Buoyancy: (Positive, Negative, Neutral) Buoyancy refers to your position in the water. Things that sink are negatively buoyant; things that float are positively buoyant; scuba divers should be neutrally buoyant (floating in the middle).

Scuba Diving Terms and Phrases: C

C-Card: Proof of scuba certification that you receive after completing your training course. This is necessary to go diving without an instructor for open water divers and is proof of any secondary/specialty scuba training and certifications you have.

Call: To “call a dive” means that you are choosing or being told to end the dive and return to the surface.

Cave: A hollow place in the ground, typically of natural formation.

Cave Diving: Entering a water-filled cave system either on scuba or freediving. Cave diving can extend thousands of feet into a cave system for people who are properly trained.

Cavern: A semi-enclosed area (often a rock formation) where you can still see the entrance and

Certified Diver: Someone who has completed scuba diving lessons through a training organization and is able to dive without an instructor.

Certification Agency: An organization like PADI, NAUI or SSI that trains people to scuba dive. There are over 100 agencies that do this, but not all certifications are valid worldwide.

Check-Out Dive: These are the dives completed outside of a pool (can be in a lake, ocean, spring, quarry, etc.) to prove that you’ve mastered a set of scuba skills and are necessary to complete scuba certification.

Confined Water Dive: Dives conducted in a pool or other shallow, current-free underwater environment so that students can master training and skills in a safe, controlled environment before completing open-water check-out dives.

Scuba Diving Terms and Phrases: D

DCS/Decompression Sickness: When bubbles of gas (often nitrogen) get trapped inside of the body. There are varying levels of severity, and can be caused by swimming to the surface too quickly.

Depth Gauge: A piece of scuba equipment that monitors how deep you are during your dive. Most dive computers serve as a replacement for depth gauges.

Dedicated Dive Resort: Accommodations that focus on scuba diving experiences. They often have a dive shop onsite, and include diving in the booking fees.

Dive Computer: A piece of scuba gear that monitors depth, bottom time and a ton of other information about each dive you complete. All dive computers are different, but they are an alternative to planning dives with dive tables.

Dive Instructor: This person has gone through many trainings and certifications (open-water, advanced-open water, rescue diver, divemaster and more) so that they can teach others how to scuba dive.

Dive Light: A flashlight designed for use underwater.

Dive Operator: A store, boat or lcoation that will take you to go diving and often can certify you as well.

Dive Table: Tool that helps determine how long you can safely stay underwater at different depths. Developed by the military to keep divers safe from decompression sickness

Divemaster: A professional-level scuba diver who has logged at least 60 dives and who is trained to assist instructors on dive boats and during certification courses.

DPV: Diver Propulsion Vehicle. A handheld and operated scooter or motor device that allows divers to move faster underwater.

Drift Dive: Diving in a current, often from a boat. Once the dive is complete, the boat picks you up at the surface.

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Dry Bag: A bag to keep any items dry that aren’t waterproof.

Drysuit: A type of exposure suit that keeps you dry while diving; used in cold-water dive conditions.

Scuba Diving Terms and Phrases: E

EAN: Enriched Air Nitrox. This is a form of mixed-gas scuba diving.

Entry: Getting into the water either from shore, boat, etc.

Equalize/Equalization: Putting air into an open area to compensate for the change in pressure. (Most commonly ear equalization for scuba divers.)

Exposure Suit: A garment worn to keep divers warm and help protect them from cuts, scrapes and other elements.

Scuba Diving Terms and Phrases: F

Fins: The scuba gear that you wear on your feet to help you swim faster/with less effort.

First Stage: Part of a scuba regulator; this attaches to the air tank.

Freediving: Diving deep or staying underwater for extended periods of time without an air tank.

Frog Kick: A technique for kicking your fins underwater. The bottoms of your feet move at each other like you’re sitting Indian style to propel you forward. This is a helpful technique to avoid kicking up sand.

FSW: Feet of Sea Water

Full-Foot Fin: A fin that covers your entire foot and most often doesn’t require you to wear a bootie.

Scuba Diving Terms and Phrases: G, H, I, J, K, L

Giant Stride: A method of getting in the water where you take a large step off the boat or dock.

Hood: Scuba gear worn over your head to help keep you warm and protect from the elements.

Hyperbaric Chamber: Air-tight chamber that can simulate the ambient pressure at altitude or at depth. This is used for treating DCS.

Inflator Valve: A manually operated valve that puts compressed air into the buoyancy bladders of a BCD or into a dry suit.

Jonline/Anchor Line: A line designed to attach to an anchor other attachment at the bottom of the seafloor. This helps guide divers to the site and allows the diver to stay in the water column regardless of wave action during decompression stops.

Liveaboard: A cruise ship, yacht or other overnight boat that is tailored to scuba divers. Most often, this will have accommodations including beds, bathrooms, gear rentals, tanks and include meals.

Logbook: A record of the scuba dives you’ve completed. This includes how deep you dived, your bottom time, who you dived with, where you dived, what you saw, how long your surface interval was, and other information relevant to your dive.

Knot: The velocity unit of one nautical mile

Scuba Diving Terms and Phrases: M

Mask: The scuba gear you wear over your face and nose.

Mask Clearing: Removing water that has gotten into your mask. You learn this skill in your open-water certification course.

Scuba Diving Terms and Phrases: N

Nitrogen Narcosis (Rapture of the Deep): An altered mental state that occurs when nitrogen enters the bloodstream at pressure. Divers experience this differently, but commonly compare it to feeling slightly intoxicated.

Nitrox: For recreational diving, Nitrox (or Enriched Air Nitrox) refers to a mixture of nitrogen and oxygen where the oxygen concentration is more than 21 percent (which is the percentage of oxygen found in normal air). Most commonly refers to 32 percent oxygen in a tank.

No Fly/No Fly Time: The recommended timeframe you should wait between your last dive and getting on an airplane. The changes in altitude can cause DCS and other issues if flying happens too soon after scuba dives.

Scuba Diving Terms and Phrases: O

O-Ring: Often made of rubber, these doughnut-shaped rings are used in various pieces of scuba gear to prevent air or water from getting in or out of that piece of gear.

Octo/Octopus: This is a secondary regulator used for emergency situations such as buddy breathing or the failure of your main regulator.

Off Gas:

Open heel fin:

Open Water: Recreational diving (outside of a swimming pool) with no overhead environments and most often at depths no more than 90 feet. Open water certification is the first true scuba diving certification you can get.

Overhead Environment: Any situation (inside a shipwreck, cave, cavern, ice, etc.) where there is an object blocking a straight route upward to the surface.

Scuba Diving Terms and Phrases: P

Pressure Gauge: A device used to measure how much air you have left in your scuba tank.

Profile (Dive Profile): An overview of your dive. This is planned before the dive, and covers how deep you will go, how long you will be underwater, how far you plan to travel and other factors.

PSI: Pounds per square inch. Measure of gas pressure

Purge: To remove contents of something; most often removing any water from your regulator.

Scuba Diving Terms and Phrases: Q, R, S

Repetitive Dives: Multiple dives completed during the same day, without many hours in between.

Safety Stop: A 3-minute “hover” at the end of your dive made between 15-20 feet. This is a precaution to be sure that excess nitrogen has a chance to get out of your bloodstream so that DCS symptoms don’t appear.

Shore Dive: A dive where you can walk from the shore into the water and find a dive site nearby.

Snorkel: A piece of gear used on the surface to breathe in place of your regulator.

Squeeze: Pain or discomfort (often in a mask, ears, and other enclosed areas, associated with the change in pressure from diving.

Surface Interval: Amount of time you’re on the surface (or in the water above 10 feet if snorkeling).

Scuba Diving Terms and Phrases: T, U, V

Technical/Tech (Diving, Limits): Technical diving is any dive that’s deeper than recreational limits. This includes cave diving, diving with special gas mixtures, dives exceeding 120 feet, and other dives that require special training.

Thermocline: A point underwater where the temperature drastically changes. Often this is visible as the two temperature “layers” meet.

Tide: The alternate rising and falling of the sea.

Vertigo: Dizziness caused by pressure differences in the inner ear. Can sometimes be a sign of trauma within the ear.

Viz/Visibility: Usually measured in feet or meters; how far away you can clearly see underwater.

Scuba Diving Terms and Phrases: W, X, Y, Z

Wall Dive: Dives that face a vertical wall, often a wall of coral reef.

Weight Belt: A piece of gear used when your BC is not weight-integrated. Weight belts hold the amount of weight a diver needs to keep from floating to the surface during dives.

Weight/Lead: Dive weights come in specified amounts and are added to a weight-integrated BC or a weight belt to keep you negatively buoyant.

Wetsuit: A tightly fitting neoprene suit that keeps you warm by allowing a small amount of water inside the suit. This comes in variations of thickness (from a a very thin “skin” to 1 mm, 3 mm, 5 mm, and 7 mm of thickness).

Wreck Diving: Diving shipwrecks, some of them unintentionally sunk and others are sunk to create artificial coral reefs. Specialty training is required to dive inside a wreck that has an overhead environment.

20 Common Scuba Diving Hand Signals

Natalie Gibb owns a dive shop in Mexico and is a PADI-certified open water scuba instructor and TDI-certified full cave diving instructor.

Oceania, Micronesia, Yap, Diver with grey reef sharks, Carcharhinus amblyrhynchos

When you’re scuba diving with friends and you need to communicate underwater, knowing these 20 common scuba diving hand signals can really come in handy and, more importantly, keep you safe. It’s a very important second language for anyone who dives. Many of these hand signals are similar to common gestures and are easy to learn.

Photo of a diver communicating "okay" underwater.

The first-hand signal that most scuba divers learn is the “OK” hand signal. Join the thumb and index fingers to form a loop and extend the third, fourth, and fifth fingers. This signal can be used as both a question and a response. The “OK” sign is a demand-response signal, meaning that if one diver asks another diver if he is OK, he must respond with either an “OK” signal in return or with the communication that something is wrong. The “OK” hand signal should not be confused with the thumbs-up signal, which in scuba diving means “end the dive.”

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‘Not OK’ or ‘Problem’

How to make the problem sign in scuba diving.

Scuba divers communicate a problem by extending a flattened hand and rotating it slowly side to side, similar to how many people signal “so-so” in a normal conversation. A diver communicating a problem underwater should then point to the source of the problem using his index finger. The most common use of the “problem” hand signal is to communicate an ear equalization problem. All student divers learn the “ear problem” sign before they enter the water for the first time.

‘OK’ and ‘Problem’ on the Surface

How to communicate okay and problem in the surface when scuba diving.

During the open water course, scuba divers also learn how to communicate “OK” and “problem” on the surface. These surface communication signals involve the whole arm so that boat captains and surface support staff can easily understand a diver’s communication from far away.

The “OK” sign is made by joining both arms in a ring above the head, or if only one arm is free, by touching the top of the head with the fingertips. To indicate a problem the diver waves his arm overhead to call for attention. Don’t wave “hi” to a dive boat on the surface because the captain is likely to think you need assistance.

‘Up’ or ‘End the Dive’

The "up" underwater communication for scuba diving.

A thumbs-up sign communicates “up” or “end the dive.” The “up” signal is one of the most important signals in scuba diving. Any diver can end the dive at any point for any reason by using the “up” signal. This important dive safety rule ensures divers are not forced beyond their comfort level underwater. The “up” signal is a demand-response signal. A diver who signals “up” to a fellow diver should receive the “up” signal in return so that he can be sure that the signal was understood.

The descend hand signal for scuba diving

The thumbs-down hand signal communicates “go down” or “descend” underwater. The “down” signal is used in the first step of the five-point descent, in which divers agree that they are prepared to begin to go deeper.

‘Slow Down’

How to communicate slow down underwater

The “slow down” hand signal is another basic signal that all student divers learn before their first scuba dive. The hand is held out flat and motioned downward. Instructors use this signal to tell enthusiastic students to swim slowly and enjoy the incredible underwater world. Not only does swimming slowly make diving more fun, it also helps to avoid hyperventilation and other dangerous underwater behaviors.

How to communicate stop and hold underwater.

Divers typically communicate “stop” in one of two ways. The first method (common in recreational diving) is to hold up a flat hand, palm forward, as a traffic cop would.

Technical divers, however, favor the “hold” sign, made by extending a fist with the palm-side of the fist facing outward. The “hold” sign is a demand-response signal: A diver who signals “hold” should receive a “hold” sign in return, indicating that his fellow divers have understood the signal and agree to stop and hold their position.

How to Communicate "Look at" underwater.

The “look” hand signal is made by pointing the index and third fingers at your eyes and then indicating the object to be observed. A scuba instructor uses the “look at me” signal to indicate that students should watch him demonstrate an underwater skill, such as ​mask clearing during the open water course. “Look at me” is signaled by making the “look” signal and then gesturing toward your chest with a finger or thumb.

Divers can also enjoy showing each other aquatic life and other underwater attractions by using the “look over there” signal, made by signaling “look” and then pointing toward the animal or object.

‘Go in This Direction’

The "Go in This Direction" Hand Signal for Scuba Diving

To indicate or suggest a direction of travel, scuba divers use the fingertips of a flattened hand to point out the desired direction. Using all five fingers to point out a direction of travel helps to avoid confusion with the “look” signal, which is made by pointing with a single index finger.

‘Come Here’

The Come Here Hand Signal for Scuba Diving

For the “come here” hand signal, extend a flattened hand, palm up, and bend the fingertips upward toward yourself. The “come here” signal is basically the same signal that people use in everyday conversation.

‘Level Off’

The Level Off hand signal for scuba diving.

The “level off” hand signal is used to tell a diver ​to remain at the current depth or maintain this depth. The “level off” signal is most commonly used to communicate that divers have reached the planned maximum depth for a dive or to tell divers to hold previously designated depth for a safety or decompression stop. For the “Level Off” signal, extend a flattened hand, palm down, and slowly moving it side to side horizontally.

‘Buddy Up’ or ‘Stay Together’

The Buddy Up hand Signal for Scuba Diving

A diver places two index fingers side by side to indicate “buddy up” or “stay together.” Scuba diving instructors use this hand signal to remind student divers to stay close to their diving partner. Divers also occasionally use this signal to reassign buddy teams underwater. For example, when two divers are low on air and ready to ascend, they can communicate that they will stay together and ascend using the “buddy up” hand signal.

‘Safety Stop’

How to communicate "Safety Stop" underwater while diving.

The “safety stop” signal is made by holding the “level off” signal (a flat hand) over three raised fingers. A diver is indicating “level off” for three minutes (the minutes signified by the three fingers), which is the minimum recommended time for a safety stop.

The safety stop signal should be used on every dive to communicate within the dive team that the divers have reached the pre-determined safety stop depth and agree to maintain that depth for a minimum of three minutes.

‘Deco’ or ‘Decompression’

The Decompression signal for scuba diving.

The “decompression” hand signal is commonly made in one of two ways—either with an extended pinkie or with an extended pinkie and thumb (similar to a “hang loose” sign). Technical divers trained in decompression diving techniques use this signal to communicate the need for a decompression stop. Recreational divers should also be familiar with this signal.

Although recreational scuba divers should never plan to make a decompression dive without proper training, this sign is useful in the unlikely event that a diver accidentally exceeds their no-decompression limit for a dive and must communicate the need for an emergency decompression stop.

‘Low on Air’

The Low-On-Air hand signal for scuba diving.

For the “low on air” signal, place a closed fist against your chest. This hand signal is not used to indicate an emergency but to communicate that a diver has reached the predetermined tank pressure reserve for the dive. Once a diver communicates that she is low on air, she and her diving partner should agree to make a slow and controlled ascent to the surface and end the dive by using the “up” signal.

‘Out of Air’

The Out of Air Hand Signal for Scuba Diving.

The “out of air” signal is taught to all open water course and experience course students so that they know how to react in the unlikely event of an out-of-air emergency. The chances of an out-of-air emergency when scuba diving are extremely low when proper pre-dive checks and diving procedures are observed.

To make this signal, move a flat hand across your throat in a slicing motion to indicate that the air supply is cut off. This signal requires an immediate response from the diver’s buddy, who should allow the out-of-air diver to breathe from his alternate air-source regulator while the two divers ascend together.

Source https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4843282/

Source https://www.scubadiving.com/dive-speak-learn-scuba-diving-terms-phrases-and-slang

Source https://www.tripsavvy.com/common-hand-signals-for-scuba-diving-2963222

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