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SPOTLIGHT Never forgotten The search for missing airmen Planes that crash in the sea during wartime are difficult to find, and the crewmen who go down with them are often surrendered to history. To help repatriate their remains, a collaboration of scientists and historical researchers has been searching for these wrecks with advanced technologies. As Steve Murray reveals, their work is also expanding the toolset available to underwater archaeology. n estimated 70,000 US last few decades, but a recent initiative 2012 to study coastal current flows for servicemen still remain – Project Recover – is unique within this the US Office of Naval Research. As with missing from the Second burgeoning tradition because it was formed previous fieldwork, the scientists were World War. Approximately with a single purpose: to help settle the accompanied by their latest equipment. two-thirds of them fought fates of missing US airmen who went A mutual friend introduced them to Dr inA the Pacific Theatre, including flyers who down during the Second World War. Pat Scannon, who was working around saw intense combat over and around New The Project Recover team is a the island at the same time as head of Guinea. Many never made it home and are collaboration of organisations which the BentProp Project. This volunteer resting today at the bottom of the bays that blends conventional underwater organisation was dedicated to finding lost surround the island. Finding a submerged archaeology methods with cutting- airmen and had already been searching plane that was lost during military action edge sensing technologies. It all began sites in the Pacific for almost 20 years. is a complicated and expensive exercise. with a lucky meeting. Eric Terrill, of the The three men recognised that a Most warplanes were already damaged Scripps Institute of Oceanography at collaboration could speed up BentProp before crashing, or broke up on impact, the University of California San Diego, Project search efforts while helping to leaving debris scattered across miles of and Mark Moline, of the College of evaluate the capabilities of the scientists’ stated unless otherwise Recover, Project GES: A seabed, mangrove, and jungle. Interest in Earth, Ocean, and Environment at the equipment and, in 2013, the new group IM LL aviation archaeology has grown over the University of Delaware, were in Palau in was established. ‘Our roots are planted in A 38 CURRENTWORLDARCHAEOLOGY Issue 91 SPOTLIGHT seen at the impact site. During a 2005 interview, members of the BentProp Project obtained additional information from a local chief that led to the discovery of a partial wing in nearby mangroves. Physical characteristics and markings confirmed that it belonged to a TBM-1C Avenger. Fresh evaluation of the evidence in 2013 showed that the Avenger case met three important criteria: good information about the crash location, indications that airmen were aboard at the time of the crash, and site conditions ikimedia Commons W that were accessible to divers. As a result, GE: A the wreck became one of the first Project IM Recover expedition targets. LEFT A United States Navy Curtiss SB2C Helldiver oceanography, engineering, archaeology, aircraft lost in the Second World War, and recently aviation, and software development, but Planning the search found resting in the tropical waters of the Republic the entire team pitches in with records Team members integrated all of their of Palau. The Pacific Theatre became a graveyard for many military aviators, but now a new initiative reviews. ‘Everyone searches,’ said Terrill, location data – photos, satellite images, is combining cutting-edge technologies and ‘it helps to look through different lenses.’ written reports, and historical records – archaeological techniques to locate the remains Once the group reaches a consensus on to build a spatial layout of the potential of lost airmen. their priority targets, they schedule the search area. They arranged their images ABOVE A TBM-1C Avenger of VT-51 over Majuro coming year’s expeditions. using photogrammetry (which establishes Atoll in May 1944. A similar aircraft, which was lost in September 1944, became one of the first targets In 2014, an early Project Recover distances and relationships through image of Project Recover. expedition selected an aircraft that never points) and commercial software. LiDAR returned from a raid 70 years earlier: in data, showing underwater topography and conventional archaeology,’ says September 1944, a flight of eight TBM-1C depth profiles, was added, and the entire Drew Pietruszka, the Project Recover Avenger torpedo bombers launched from data set was aligned to selected geographic underwater archaeologist. ‘We just tweak the aircraft carrier USS Intrepid to strike references. The team then compared things.’ Their approach includes standard facilities around Japanese-held Palau. One objects in their layout to equivalent practices such as records reviews, survey of the last planes in the attack dropped its planning, search, and documentation, bombs at an altitude of 305m, but crashed BELOW Fusion of declassified historical black- but stops short of excavation. The US offshore when the resulting explosion and-white photo reconnaissance imagery from Department of Defense POW/MIA damaged its tail. An after-action report Palau, March 1944, showing the intended target of a missing TBM-1C Avenger torpedo bomber. Accounting Agency (DPAA) has the stated that debris was sighted in the The fused data were used to identify the search sole responsibility for collecting and area and that one of its three crewmen region for the REMUS AUV and the probable examining remains from personnel probably bailed out. No survivors were trajectory of the damaged aircraft as it flew offshore. who are missing in action (MIA); Project Recover seeks to bring back the information that helps initiate DPAA recovery missions. Tweaked archaeology The team begins by deciding which candidate sites are worth looking for. This involves pinning down a search location and confirming that missing airmen are associated with the site. Team members review everything they can get their hands on, including combat photos, after-action reports, personnel files, diaries, and eye-witness statements. BentProp members have even attended military reunions to gather information about crash sites. Project Recover combines expertise in www.world-archaeology.com CURRENTWORLDARCHAEOLOGY 39 ABOVE & RIGHT A REMUS 100 AUV over an intact Corsair wreck. The inset image shows the side-scan sonar mosaic generated from multiple REMUS 100 sorties during a wide-area search. Several targets identified during this process were later examined and shown to contain aviation wreckage dating from the Second World War. structures shown in 1940s photographs The result was a composite probability Finding what of the same area. model of the ‘most likely’ crash location. they came for Once this information had been The uncertain last seconds of the Once a wreck is located, the next challenge assembled, Project Recover used both Avenger’s flight path and the influence of is to identify it. ‘We look for multiple lines forensic data analysis and Bayesian decades of ocean currents and tides still left of evidence’, says Pietruszka, ‘to make a probability methods to estimate the the team with a sizable survey task. Project case that will connect a site to a specific loss aircraft impact location. Although Recover employed autonomous underwater incident associated with specific missing Bayesian techniques sound complicated, vehicles (AUVs) equipped with side-scan airmen. We look for data plates, paint they are simply a way to combine sonar for the initial work: identifying schemes, numbers – anything to identify information from multiple, often objects that deserved closer inspection. a plane beyond just its type. We also look conflicting sources, in a manner similar Their torpedo-shaped REMUS 100 (Remote for modifications that might distinguish to the methods used in searches for Environment Monitoring UnitS) vehicles a particular plane, like the bolt pattern more recent air crashes. Now Project could operate for about ten hours, covering of the propeller or its machine-gun serial Recover analysts are helping to elaborate large regions of the seafloor in a back and numbers.’ These examinations must be these procedures for underwater forth ‘mow-the-lawn’ scan pattern. In tight thorough. Another Project Recover team archaeological work. spaces or near underwater obstacles, studied a wreck thought to be a B-24 Using the location of the Avenger’s the team supplemented these surveys Liberator bomber off the coast of Greece. probable bomb target, the position of its with human-operated sensors tethered to Despite gathering significant information partial wing, and eye-witness reports from small boats or carried by divers. Different about the site prior to the expedition, the Avenger’s wingman and from the sensor packages such as multibeam sonar inspection of its landing gear configuration Palauan elder’s interview, it was possible (which covers a smaller scan area at higher showed it to be a British Short Stirling to estimate the aircraft’s crash trajectory. resolution), thermal imaging, and optical bomber. The information was turned over The team then ran numerical simulations cameras were employed as necessary to to the British Ministry of Defence. to construct alternate scenarios of the gather information in different light and Only after a plane’s identity is pinned Avenger crash using their position data, visibility conditions. All of this imagery down does the team begin their painstaking historical reports of the event, and TBM-1C was then stitched together to create a search for personal items like clothing, flight mechanics (turn rate, glide angles, high-resolution mosaic of the entire boots, oxygen masks, or rings that could bank angles, elevation, speed, and so on). search effort. connect individual crewmen to the 40 CURRENTWORLDARCHAEOLOGY Issue 91 SPOTLIGHT LEFT A side-scan image of the TBM-1C Avenger found by Project Recover. The crash is spread across a 70m debris field.