More than 72,000 Americans who fought during World War II (WWII) remain unaccounted for, and more than half of them are presumed lost at sea. U.S. government entities have investigated WWII sites over the past 70 years to find evidence of those missing in action (MIA) but have faced challenges, particularly when trying to explore strategic locations on the seafloor. Recent advances in autonomous underwater vehicles (AUVs) and underwater imaging technologies are making it possible to search deeper and more challenging parts of the ocean to potentially find some answers in wreckages, a task that has historically fallen upon divers.
In March, a U.S. research team, including oceanographers and forensic archaeologists, completed a 2-week mission to search for planes that had crashed in the northwestern Pacific Ocean in 1945. The team found two crash sites.
“There are lots of unanswered questions across generations. So being able to find and identify crash sites pays homage to those that were before us,” said Eric Terrill, a researcher at Scripps Institution of Oceanography and cofounder of Project Recover.
Launched in 2012, Project Recover is a collaboration between Scripps (a division of the University of California, San Diego (UCSD)) and the University of Delaware. It expanded on an earlier project created by scientist Pat Scannon, and the combined efforts have so far located more than 50 aircraft associated with 185 American MIAs.
Search for Superfortresses
Tinian, part of the Northern Mariana Islands, was seized by Allied forces in 1944 and used as an airbase for long-range bombing of Japan, located 2,000 kilometers (about 1,243 miles) north. These campaigns were the first combat use of the Boeing B-29 Superfortress, which was retired in 1960.
B-29s were rushed into the action in the Pacific, and many crashed on takeoff because of overheating turbochargers. By searching through Missing Air Crew Reports and other personnel files, the Project Recover team identified 13 crashed planes within a 93-square-kilometer patch of ocean, linked with 76 American MIAs.
With this in mind, Terrill’s 11-person team set sail from Guam in late February aboard the R/V Kilo Moana to search for WWII wreckage sites between Tinian and Saipan, the largest of the Northern Mariana Islands.
During the expedition, the team explored 500–600 meters below the ocean’s surface with side scan sonar systems operated from two REMUS 600 AUVs. Once objects of interest were located, the team sent down a smaller remotely operated vehicle equipped with a high-resolution camera.
According to crew member Andrew Pietruszka, an underwater archaeologist at UCSD, the team located two planes, though neither appears to be a B-29. One aircraft is a recognized type of U.S. military plane from the WWII era, whereas identification of the other is less clear—it could be American or Japanese, according to the research team.
A Long Journey to Find Closure
“Typically, we would be ecstatic if we went to do a survey and found two new aircraft. But I think there was a little bit of a let down because we didn’t find any of the B-29s,” said Pietruszka. High seas had posed challenges, and the team would like to return for a follow-up mission once funding is secured. All findings will be shared with the historical preservation office of the Northern Marianas. “This is their history as well as our history, they’re intertwined,” he said.
Once Project Recover scientists have identified planes from tail numbers and other clues, the recovery of human remains is done by dive teams under the management of the Defense POW/MIA Accounting Agency (DPAA). Given the sensitivities and legal complexities, it can take years for a person’s status to change from MIA.
But the efforts can pay off. In 2020, Project Recovery’s work enabled the DPAA to make its first recovery from Vietnamese waters aided by a nongovernmental organization. U.S. Air Force Maj. Paul A. Avolese, killed during the Vietnam War, was identified, then buried on 24 July 2021.
Pietruszka, who used to work for the DPAA himself, said he hopes that UAVs can start being used in the recovery process to access locations inaccessible to divers. Recent advances in machine learning could also help autonomous systems identify plane wreckage and bone fragments when visibility is poor. In addition, new technologies can be used beyond exploring cultural sites—in 2021, the same Project Recovery team used these techniques to detect barrels of DDT (dichlorodiphenyltrichloroethane) at a dump site off the coast of Los Angeles.
—James Dacey (@jamesdacey), Science Writer