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Navy Develops and Tests Rapid Pressure Fluctuation Chamber to Study Physiological Events

By Katherine Mapp | NSWC PCD Public Affairs | March 25, 2019

PANAMA CITY, Florida —

A Navy team is developing a solution for detecting symptoms associated with rapid pressure fluctuations in military jets, a phenomenon associated with physiological events (PE) in the E/A-18G and F/A-18 weapon systems. 

Naval Surface Warfare Center Panama City Division’s (NSWC PCD) Fluctuating Altitude Simulation Technology (FAST) team recently delivered an aircraft cabin simulator system to the Navy Experimental Diving Unit (NEDU) for their use conducting human subject research.

NSWC PCD engineers designed and fabricated the FAST system to replicate the rapid cockpit pressure fluctuations observed in the Navy’s jet aircraft.

“The purpose of the FAST system is to characterize the symptoms associated with rapid pressure fluctuation, and determine what symptoms may be most closely associated with PE,” said Navy Research Psychologist Lt. Jenna Jewell. “This information allows us to conduct future research that can be more targeted, including focusing on specific symptoms and adding in factors present in the cockpit.”

Aircrews experience PEs when there is both a known or suspected aircraft or aircrew systems malfunction and a loss in performance related to insufficient oxygen delivery, alterations in breathing dynamics, unexpected pressure phenomenon, or other human factors. Research “flights” were conducted at NEDU from November 2018 to January 2019 to simulate the rapid cabin pressure fluctuations aviators experience during flights in a controlled environment. This allowed medical researchers to investigate whether there are physiological or neurocognitive impacts due solely to the pressure fluctuations.

The team began with a commercial-off-the-shelf (COTS) Double Occupancy Altitude Chamber (DOAC) to simulate the cockpit environment and modified the features to meet operational objectives, according to Brian Toole, NSWC PCD FAST project manager.

“The NSWC PCD FAST team designed and assembled the FAST system in-house,” said Toole. “NSWC PCD brought the concept to reality by starting with the COTS DOAC and installing our own control system, developing algorithms, and programming the NSWC PCD designed chamber software to meet mission requirements.”

According to NEDU Research Physiologist Lt. Travis Doggett, the FAST study is moving the Navy one step closer to solving critical safety concerns.

“This study is the first-of-its-kind human subject research investigating PEs plaguing Naval Aviators by replicating the cabin pressure fluctuations observed in the Fleet. It is also the first-ever study to investigate and identify the physiological responses and symptomology associated with rapid cabin pressure fluctuations at altitude,” said Doggett.

“The FAST system, coupled with the manned testing, will provide Navy leadership vital information needed to help solve the Chief of Naval Operations number one aviation safety concern – impacting the Navy’s ability to operate safely in the airspace of its choosing, without physiological hindrance,” Doggett added.  

 

How it works

Before simulated flight, participants undergo an initial general medical evaluation to determine inner ear function, retinal tracking, and a neurocognitive exam. Upon completion, participants enter the FAST chamber and fly one of three predetermined flight patterns. During the flight, participants’ vital statistics are tracked constantly and a Doppler ultrasound test is conducted at four different occasions to determine if venous gas bubbles are present in each participant’s heart. In addition, retinal function is tested mid-flight.

Upon completion of the flight, participants undergo the same pre-flight testing to determine if there are any changes in physiological or neurocognitive performance as a result of the rapid pressure fluctuations experienced during simulated flight.

NSWC PCD’s FAST team used their life support expertise to meet this urgent need, rapidly developing the technology by pursuing parallel paths and efficient use of existing assets. The FAST team went from refining conceptual requirements in November 2017 to delivering a fully functional system to NEDU in May 2018.

“Our team at NEDU knew what we wanted to accomplish at the end. We had an idea of the question we wanted to answer, but did not have anything in terms of how to actually make it happen,” said Jewell. “The partnership between NEDU and NSWC PCD is how we got to a solution. For all of this to come to fruition within 14 months of beginning, and now we have a new system that NAVAIR is going to continue relying on to use in the future, is huge for us.”

The FAST cabin is one key step in identifying, mitigating and eliminating environmental factors causing PEs during military aircraft flights. This study is only the first of multiple steps. The next phases include adding additional factors to determine how pressure fluctuations can affect aircrew.