After some research, Hwang seized on the United Nations’ Convention for the Suppression of Unlawful Seizure of Aircraft, ratified by the North in 1983.
“Since the crew members and passengers have not arrived at their final destination, the plane is still in flight according to the treaty,” he said.
Seoul could demand the North abide by the international agreement and free the abductees, Hwang said — but his pleas for government action have gone unanswered.
Initially Seoul had encouraged the hijacking victims’ families to keep a low profile, saying their actions could complicate their relatives’ lives in the North.
Inter-Korean relations have gone from warm to cold and back again in his years of campaigning, but the diplomatic process has made no difference to his quest.
South Korean President Moon Jae-in met three times with the North’s leader Kim Jong Un last year, but Hwang remained a bitter onlooker.
“It was just an extension of the empty calls for reunification that I’d heard during the previous liberal administrations,” Hwang said.
“Humanitarian issues — by far the most important — have always been left out.
“The ignorance and indifference of the South Korean government has turned into a huge pain for me.”
At the UN’s Universal Periodic Review of human rights in North Korea in May, Iceland and Uruguay specifically demanded Pyongyang release the remaining hijacking victims, but Seoul only asked it to “address the issues of abductees and prisoners of war”.
The South’s unification ministry — which handles cross-border affairs — declined to comment to AFP on whether the hijack victims were discussed during last year’s summits.