News | Jan 22, 2020

Air Force invents new device for swimmers, former PJ instructor believes it could save lives

"There's an opportunity here for a business to directly support the warfighter community with a product that has an obvious dual-use, commercial market."

Pararescue Jumper/Combat Rescue Officer Indoctrination Course candidates practice water skills during their extended day of training conducted in Joint Base San Antonio - Medina. The PJ/CRO Indoc is a nine-week course conducted by the 350th Battlefield Airmen (BA) Training Squadron, BA Training Group, 37th Training Wing, AETC.

Johnny Saldivar/Air Force

The U.S. Air Force Research Laboratory tasked scientists and engineers at the 711th Human Performance Wing with building a device that would help instructors know when student swimmers were about to black out in the pool.

The project has matured, producing an electronic device called the FISH, with several prototypes tested. Private companies are now being sought to license and commercialize the technology for military and non-military customers.

“I had a team commander who passed away while I was going through Indoc and something like this could have likely saved him,” said Brian Silva, a former Air Force pararescue jumper (PJ) and owner of

In the Wake of Tragedy

February 2006. It was “Black Thursday,” a grueling day of physical challenges during the seventh week of the Air Force’s 8-week pararescue jumper training course known as “Indoc.”

After a ruck march, a group of trainees including Maj. Bryan Adrian prepared for a session of pool exercises completed while wearing combat fatigues.

Adrian, 41, was a highly motivated pilot who wanted to transition from the Air National Guard to the Air Force’s elite special warfare community.

Pararescue Jumper/Combat Rescue Officer Indoctrination Course candidates practice water skills during their extended day of training conducted at Joint Base San Antonio–Medina in 2017. (Johnny Saldivar/Air Force)

The pool they swam in was 25 meters long and had a depth of nine feet at the deep end. After several warmup exercises, instructors briefed the trainees on their next task, a 50-meter underwater swim.

Swimming the lap requires holding your breath for over a minute. It’s assumed that some trainees will pass out – Adrian did.

After he was lifted out of the pool, an attempt to shake Adrian awake failed, so did rescue breathing. An automatic defibrillator was deployed; an ambulance took Adrian to the emergency room, but tragically, he died.

An internal Air Force investigation revealed that Adrian suffered a heart attack caused by a pre-existing condition called Long QT Syndrome.

“He was a complete stud, probably in better shape than I was throughout Indoc, he was just a machine the entire time, even going on runs, he never showed any pain or any weakness,” said Silva.

A Problem for Pilots and Swimmers

Hypoxia is what scientists call running out of oxygen, and it can cause your heart rate to spike, loss of consciousness, and eventually death.

The Air Force Research Laboratory at Wright-Patterson Air Force Base puts hypoxia at the top of the list of problems they don’t want pilots to have.

To understand why pilots were experiencing hypoxia despite wearing oxygen masks, scientists and human performance engineers at the Air Force lab built pulse oximeter devices.

Then they imagined the same technology could be adapted for swimmers.


The FISH is a small pulse oximeter with blinking LEDs (the acronym stands for Flashing Indicator of Swimmer’s Health). The device is battery powered and attaches directly to the swimmer. It overtly notifies bystanders (instructors) when a swimmer is experiencing a downward trend in blood oxygen saturation.

The first prototypes were constructed in 2016 and 2017, leveraging the research on pilot hypoxia.

Illustration of the goggle-mounted FISH. The Air Force was assigned U.S. Patent 10,413,225 for the FISH in September 2019.


Dr. Gregory Burnett of the 711th Human Performance Wing is one of the FISH’s inventors, according to U.S. Patent 10,413,225 (linked below).

The device could be used in a non-training situation whereas a remote observer, say a parent, wants to have a visual notification when their child is becoming fatigued and their SpO2 levels are dropping. Or, for competitive swimmers, the technology could potentially be used to increase endurance through lung training.

Because there may be up to 40 trainees in the pool at one time, the FISH begins to blink green when a swimmer’s oxygen level begins to drop, changing to red to alert instructors to which swimmers are nearing a dangerous blood oxygen limit. To accommodate depth training, the light was made bright, according to a recent Air Force promo video.

Ready for Production

There are two versions of the FISH; the first mounts to the swimmer’s goggles, the second is an arm sleeve, which has been the focus of the research team.

Silva, a former Indoc instructor, said that the Air Force has experimented with similar chest-mounted devices for monitoring student health in the pool, but thinks the FISH’s new form factors may prove better.

“The first reason being that most of the time when the students are in the water they are wearing a shirt of some sort and in the higher intensity session they will be wearing a shirt and an ABU top,” Silva said in an email, referring to the Airmen Battle Uniform, the Air Force’s standard-issue, long-sleeved blouse.

“Wearing these garments on top of the device diminishes the ability to visualize the LED as well as the signal to the receiver. The second reason it was ineffective is because there is only a sensor on one side of the strap meaning that when a person is turned away from the receiver the student’s body would be blocking the signal and causing the light to cast on to other trainees around them making it difficult to tell who was the person blinking, he said.

“Lastly, the placement of the LED on a student’s head would allow us as instructors to visualize the student’s eyes, inspecting for the level of consciousness while simultaneously examining for periorbital cyanosis. These are the first signs we look for in a person who is hypoxic.”

Because the FISH is at a high technical readiness level, it is ready for a commercial partner who can finalize development and begin offering it publicly as a new product.

1LT David Sardo, Air Force special warfare biomechanical engineer, adjusts the FISH sleeve. (Air Force photo)


Because the Air Force has been issued one patent for the FISH, and two more are pending, the process of transferring the technology to a private company for commercialization starts with a patent license agreement.

Marti Elder, senior technology manager at TechLink, is a veteran of Air Force technology transfer. After communicating with Burnett, she’s now searching for a company to make and sell the FISH, to military or non-military customers.

“This is an excellent opportunity for a business to support warfighters with a product that has an obvious dual-use, commercial market,” Elder said. “We’ve begun deliberate, targeted outreach to businesses and are ready to help them review the tech, and move forward with licensing and commercialization.”

Inquiries about the FISH can be sent to Marti Elder at or she can be reached by telephone at 406-586-7621. TechLink is the Department of Defense’s national partnership intermediary for technology transfer. TechLink’s services are made available to businesses at no cost.