NORTHERN VIETNAM -- The Defense POW/MIA Accounting Agency (DPAA) deployed an Underwater Recovery Team (URT) comprised of Department of Defense civilians and U.S. Army, Navy and Air Force service members to northern Vietnam in search of two U.S. Navy aviators who went missing during the Vietnam War, May 2 - Jun 18.

The two men were on a nighttime reconnaissance mission over northeastern Nghe An and southeastern Thanh Hoa provinces when their F-4B Phantom aircraft vanished from radar, Sept. 21, 1966. To this day, the two men remain unaccounted-for.

This is not DPAA's first mission to this site; in 2008 an underwater investigation team used remote sensing equipment to identify possible wreckage on the bottom, and then employed divers to verify what was detected. This technique led to the discovery of the aircrafts' wreckage site.

"We spent several previous missions refining an area of relatively higher interest within the larger site," said Dr. Piotr Bojakowski, an underwater archaeologist and scientific recovery expert with DPAA. "On this mission, we are conducting systematic test excavations across a larger area, to further refine the wreckage debris field, with the intent to locate where diagnostic evidence may have been deposited."

The physical retrieval of this evidence is being conducted by Army divers, assigned to 7th Dive Detachment, 84th Engineer Battalion, stationed at Oahu, Hawaii. Through surface-supplied diving operations, they dredge the bottom one, two by four-meter grid square at a time.

The dredging is done utilizing a Venturi system, which regulates the pressure of the material as it is pumped through a constricted space. In this case the constricted space is a six-inch pipe connected to a large metal basket.

"The diving conditions are less than ideal, water is dirty and visibility is almost zero," explains Staff Sgt. Humberto Santiago, a diving supervisor assigned to 7th Dive Detachment. "The bottom type here has been pretty difficult, some grid squares are on soft bottom and others are on hard packed mud-- these require a lot more exertion from our divers and are more time consuming."

Once a basket is filled on the bottom, a crane lifts it approximately 20 feet to the surface and places it on a barge where other team members sift through its contents. The material from the seafloor is placed in screens where dirt and mud are rinsed away by hand, leaving residue that is easier to sift through and allows team members to more readily identify any human remains or aircraft wreckage that may potentially be present, and to collect any other possible evidence.

"The screening station is pretty straightforward, it is where all material from the bottom is examined," said Santiago. "For team members, this is the time to be very thorough and very methodical, but it is all worth it when we do find something of interest."

If a team member does find something of evidentiary value it is placed in a bucket identifying which grid square it came from and further analyzed and recorded by Bojakowski. If possible human remains are discovered, a joint forensic review team will be sent from DPAA headquarters in Hawaii, and together with Vietnamese officials, they will conduct further analysis to determine if they should be sent to the laboratory for analysis and DNA testing.

The URT spent about six weeks in Vietnam searching for signs of the lost aviators in hopes of providing a full account of the status of these heroes to their families and the nation.

"These underwater recovery missions with DPAA are by far the best," said Santiago. "There is no greater satisfaction than having the opportunity to truly make a difference in the lives of past service members' families and we take great pride in being part of something as rewarding and honorable as this."