The Pentagon agency that searches for missing service members from the Himalaya Mountains to the jungles of Papua New Guinea is mounting a recovery this summer for a naval aviator who has been missing in the group’s backyard since World War II.

Between Aug. 8 and Sept. 30, the Defense POW/MIA Accounting Agency plans to seek the remains on Oahu of Ensign Harold P. DeMoss, whose F6F-3 Hellcat went down during a night training mission on June 23, 1945, in the Koolau Mountains.

The effort, which is complicated by the remote terrain, is expected to require up to 12 personnel and military helicopters at a cost of more than $550,000.

The blue-eyed, sandy-brown-haired pilot, just 21 years old, was part of a formation of three Hellcats that took off from Naval Air Station Barbers Point at 1:05 a.m. Near Kahuku Point, the fighters ran into clouds at 3,000 to 6,000 feet, and DeMoss became separated from the group. At 10 a.m., a crashed and burning plane was spotted.

Three days later, a search party found the still-smoking plane in rugged terrain and buried the remains of a person who could not be identified.

Clarence and Mary DeMoss made inquiries to the Navy about recovering their son, who served as a reservist. The years stretched into decades, and the hope to see Harold DeMoss returned for burial in the family graveyard passed from parents to a brother to a niece, Judy DeMoss Ivey.

“I’m stunned,” Ivey said when told the Defense POW/MIA Accounting Agency has plans to head to her uncle’s crash site this summer. “I think that would be terrific.”

The Nashville, Tenn., resident said the family has been seeking a recovery for so long.

“My dad has given up, and I told him it would just take awhile, and you know, hang in there, we’re trying,” Ivey said.

James DeMoss, Harold’s younger brother, now is 83.

“It’s just taken so long that you kind of think they (the agency) are actually not going to do this,” Ivey said. “They are going everywhere else, but they are not going to do this one.”

The agency, formerly the Joint POW/MIA Accounting Command, searches for, recovers and identifies Americans missing from past wars, often traveling to far-flung places to do so. Its Central Identification Laboratory and the bulk of its operations are based out of Joint Base Pearl Harbor-Hickam.

Navy officials for years pointed to the remoteness of the site — less of a challenge now — as the reason for not recovering DeMoss. Since 2011, meanwhile, the holdup has been due more to government bureaucracy.

The Navy’s Bureau of Medicine and Surgery said in a 1948 letter to the family that “an attempt to recover the remains was considered impracticable” because the site was 7 miles from a traveled highway in the mountains and could only be reached “on foot over rocky ledges, through heavy undergrowth and over extremely rugged and dangerous ground.”

In 1967, the Navy rejected the family’s request for government transportation to Hawaii to visit the grave. It also said that “due to the remoteness of the location where your son’s aircraft crashed, it is almost impossible to reach this area by normal means of transportation.”

Ivey, now 64, said in 2011 that her father, who had taken over the quest, “didn’t know where to begin.” He had “little bits and pieces. I didn’t know what to do, either, until I started trying to tie it all together.”

She had read about another missing aviator on Oahu, Navy Ensign Harry Warnke, also a Hellcat pilot, whose remains were recovered in 2006 from a cloud-covered mountaintop near the Kaneohe side of the H-3 tunnel.

The Hawaii Aviation Preservation Society eventually was contacted, and its members, using their own helicopter support, found the DeMoss crash site in late 2011 after multiple treks to the area.

“I could not say enough good things about (them),” Ivey said. “I couldn’t imagine doing that the way they did. They took this on like it was their immediate family.”

Defense POW/MIA Accounting Agency said the oldest document in its files related to DeMoss is from 2011 — when the aviation society contacted it. But an environmental assessment was needed before a recovery was conducted. Maj. Gen. Kelly McKeague, then the commander of the agency, said in a late 2013 email that a survey of the surface wreckage and terrain features had been conducted in 2012.

“It was clear that any excavation work would be subject to stringent reviews and approvals required by the National Environmental Policy Act,” McKeague said in reference to the environmental assessment.

The $184,000 environmental assessment contract was awarded on Sept. 24, 2013, McKeague said. He noted that environmental assessments take about a year. That one was finally completed in August 2015. Maj. Jessie Romero, an agency representative, said the assessment took longer than expected because the initial plan for recovery operations, involving excavation and screening of dirt for human remains at the recovery site, had to be scrapped “due to unfavorable site conditions.”

“A decision came late in the process to change the recovery method involving a more costly approach by helicopter sling-loading excavated material to a remote site where drying and screening operations could be conducted,” Romero said.

The change in game plan resulted in a rewrite of the assessment and required additional review of the military helicopter paths to and from the site.

The agency “has had to comply with statutory requirements in order to work in this protected area,” Romero said. “But we remain focused on seeing this through, as evidenced by the resources we have and are putting into action to pursue this case.”

Romero said the total cost of the assessment was $184,525. About $550,000 total is the preliminary budget for the recovery, but that doesn’t include helicopter support and environmental restoration, he said.

Ivey said until she received the news of the scheduled recovery, she and her father planned to put up a symbolic headstone for DeMoss in the family cemetery in Nashville, where DeMoss family members who served in the Civil War, and World Wars I and II are buried.

That’s on hold now while the family waits, a bit longer, to see if they can bury the naval aviator next to the parents who never had closure for the son they lost on a Hawaii mountainside in 1945.