Marty Ross-Dolen went to Green-Wood Cemetery to stand by a monument that her grandparents’ names are on. The monument is “hidden back there,” she said. “You don’t know that people even know about it.”

She herself didn’t know much about why her grandparents’ names belonged on the monument until nearly 20 years ago, when she was in her mid-40s and finally read up on something that was almost never talked about when she was growing up: a midair collision over New York Harbor in December 1960.

Her grandparents — her mother’s mother and father — had been passengers on one of the two planes.

“The plane crash had been a part of my life since I asked my mother where her parents were,” Ross-Dolen said. “I must have been 4. I knew who they were because there were pictures around the house, and I was named for my grandmother. But my mother raised me in silence. In the 1960s, there was no language for processing grief.”

Ross-Dolen, who learned that language on her way to becoming a child psychiatrist and a writer, has processed more than grief in a just-published memoir, “Always There, Always Gone: A Daughter’s Search for Truth” (She Writes Press). It is a very personal account of the aftermath of a disaster that captured attention for a few days. Then the world moved on — for everyone else.

Her mother’s parents, Garry and Mary Myers, ran the magazine Highlights for Children, which Garry Myers’s parents had started after World War II. Ross-Dolen said the trip to New York, with another Highlights executive, had a purpose. Her grandparents wanted to see about getting Highlights for Children on newsstands.

They boarded a Trans World Airlines plane in Columbus, Ohio, where they lived and the magazine had its headquarters. New York was little more than 90 minutes away on the propeller-driven Super Constellation, and as it pushed through sleet and fog, air traffic controllers cleared it to descend to 5,000 feet on its way to landing at LaGuardia Airport.A different plane heading toward a different airport was also preparing to land — a United Airlines DC-8, bound for what was then known as Idlewild Airport (now John F. Kennedy International Airport). The two aircraft should never have been less than three miles from each other. But the jet, which had transceiver trouble, was not over New Jersey, where the pilots and the air traffic controllers assumed it was. It was already over Staten Island.

And then the two dots on the radar screen merged into one. In all, 134 people died — 128 passengers and crew members on the two planes, and 6 people on the ground in Brooklyn, where wreckage from the United plane landed in Park Slope.

“There was one time in high school when I discovered my mother looking at old newspapers,” Ross-Dolen said. “I didn’t inquire. I didn’t try to find those articles.” But in 2008, with a little time on her hands, “I decided to sneak, almost like a kid, and see what had happened.”

And by 2008, there was Google, which made her search easier.

“I’m sure I was shaking when I was reading about it,” she said.

Then, in 2010, as the 50th anniversary of the accident approached, she and her mother talked about it — to a reporter from The Columbus Dispatch, who had asked to interview her mother. “We were trying to hold ourselves together,” Ross-Dolen said. “It became less a mother-daughter thing and more partners in mourning.”

In The New York Times’s articles about the anniversary, I wrote that it was “almost a ghost disaster, one without the universally shared imagery of the Titanic or the Hindenburg, one that is, in a strange way, nearly forgotten by those who weren’t there or touched directly by it.”

Ross-Dolen was touched by it, even though she was born six years after it happened. She began working on her book after the monument was unveiled on the 50th anniversary of the crash. She said that seeing it again last week was “profound,” because she had a feeling of coming full circle.

“Fourteen years ago, I was standing there with people who had been connected to the story of the accident,” she said. “This time, I was standing by myself, but I was also putting my story into the world.”