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What Really Happened to Dag Hammarskjold’s Plane

More than 60 years after the deaths of the U.N. chief and his team, the victims’ families believe the answer may lie in Washington’s and London’s archives.

The wreckage of Dag Hammarskjold’s plane
The wreckage of Dag Hammarskjold’s plane
The wreckage of Dag Hammarskjold’s plane, which mysteriously crashed near the town of Ndola in modern-day Zambia in 1961. AFP via Getty Images
By , a senior staff writer at Foreign Policy.

Last September, U.N. Secretary-General António Guterres marked the 60th anniversary of the death of his predecessor Dag Hammarskjold, who was killed in a mysterious plane crash in Northern Rhodesia, now Zambia, on Sept. 18, 1961, by laying a wreath alongside the names of other fallen U.N. staffers.

But in his tribute—which hailed the late Swedish diplomat as a “noble servant of peace”—Guterres neglected to mention any of the 15 other U.N. advisors, bodyguards, and crew members who also perished aboard Hammarskjold’s Douglas DC-6 airliner, named the Albertina, or later due to their injuries.

The omission rankled many descendants of the crash victims, who took it as the latest sign that the United Nations has been conducting a listless investigation into one of diplomacy’s most extraordinary cold cases of the 20th century. But the inquiries—which examined new evidence suggesting that Hammarskjold’s plane may have been targeted for attack—have been ultimately stymied by the refusal of powers such as the United States, Britain, and South Africa to fully open their intelligence archives from the period to U.N. investigators.

The wreckage of Dag Hammarskjold’s plane
The wreckage of Dag Hammarskjold’s plane

The wreckage of Dag Hammarskjold’s plane, which mysteriously crashed near the town of Ndola in Northern Rhodesia, now Zambia, in 1961. AFP via Getty Images

Last September, U.N. Secretary-General António Guterres marked the 60th anniversary of the death of his predecessor Dag Hammarskjold, who was killed in a mysterious plane crash in Northern Rhodesia, now Zambia, on Sept. 18, 1961, by laying a wreath alongside the names of other fallen U.N. staffers.

But in his tribute—which hailed the late Swedish diplomat as a “noble servant of peace”—Guterres neglected to mention any of the 15 other U.N. advisors, bodyguards, and crew members who also perished aboard Hammarskjold’s Douglas DC-6 airliner, named the Albertina, or later due to their injuries.

The omission rankled many descendants of the crash victims, who took it as the latest sign that the United Nations has been conducting a listless investigation into one of diplomacy’s most extraordinary cold cases of the 20th century. But the inquiries—which examined new evidence suggesting that Hammarskjold’s plane may have been targeted for attack—have been ultimately stymied by the refusal of powers such as the United States, Britain, and South Africa to fully open their intelligence archives from the period to U.N. investigators.

“It did not go unnoticed that in your comments marking the 60th anniversary of the crash you paid tribute to former Secretary General Dag Hammarskjöld without making any mention of those accompanying him,” Hynrich Wieschhoff wrote to the U.N. chief last December, in a letter that was signed by more than 100 other relatives of the victims. “They too were United Nations civil servants or working on behalf of the United Nations. And, they too lost their lives in service to the United Nations.”

“Disappointed as we are, we are not surprised,” added Wieschhoff, whose father, Heinrich Wieschhoff, was an anthropologist who served as one of Hammarskjold’s political advisors. “As we perceive it, your failure to honor the service and sacrifice of our loved ones is consistent with the indifference that the United Nations has shown to uncovering the truth about the cause of the crash.”

The vast majority of the descendants of the victims of the crash believe that the plane was brought down by foul play, most likely attacked by a European mercenary group employed by a Belgian mining company in support of a secessionist rebellion in the mineral-rich Congolese state of Katanga, according to two family members. Hammarskjold was on his way to mediate an end to the secession and civil war in the breakaway state when he was killed in the crash.

They fear they are running out of time to get to the bottom of what happened. Key witnesses from the time period are dying off, and the U.N. inquiry, led by former Tanzanian Chief Justice Mohamed Chande Othman, is set to conclude in September without having established conclusively the circumstances of how the plane crashed. Othman has been investigating the case on and off for the U.N. since March 2015.

Sven Goran Hallonquist was 10 when his father, Per Hallonquist, piloted Hammarskjold’s plane on its final flight. Through most of his life, he said, he has been unable to say with certainty whether the crash that killed his father was an accident or if the plane was brought down by hostile forces. That all changed about six or seven years ago, when the son of the plane owner’s chief engineer provided him with a copy of the original Rhodesian technical report, which indicated that the plane made an erratic maneuver shortly before it crashed, suggesting it was evading a potential threat.

“I think that is the most probable thing—that it was shot down by another plane,” Hallonquist said, noting that the vast majority of victims’ families believe so, too. Hallonquist said he and other relatives of the victims want the U.N. to pursue the case more vigorously and the U.N. chief to take a more personal role in seeing the case through.

“We think we need to put pressure on him to try to pressure the United States and Britain and South Africa for more resources to search their archives,” he said.

Over the years, Othman has amassed a “significant amount of evidence,” including the testimony of African eyewitnesses suggesting foul play was largely ignored by early investigations in the 1960s. That goes against claims by British colonial authorities in Northern Rhodesia at the time that Hammarskjold’s death was an accident. Othman has explored a theory that a mysterious aircraft may have either fired on Hammarskjold’s plane or harassed the pilot, causing it to crash, or even that the plane may have been sabotaged by South African mercenaries, allegedly with the aid of the CIA and other Western intelligence agencies. The CIA has previously denied involvement in the alleged Operation Celeste.

Othman said in his two previous reports, issued in 2017 and 2019, that the “burden of proof” was on member states to demonstrate that they have conducted a thorough review of their records and archives, particularly from their intelligence agencies. “[T]he continued non-disclosure of potentially relevant new information in the intelligence, security and defence archives of Member States constitutes the biggest barrier to understanding the full truth on the event,” Othman wrote in his 2017 report.

The governments of Zimbabwe, Zambia, and the Democratic Republic of the Congo have appointed high-ranking figures, including Sydney Sekeramayi, a former Zimbabwean defense minister, to oversee the search for documents and have provided full access to their archives. Belgium, France, and Sweden have also granted extensive access to their security files. But the United States and Britain have been less forthcoming, appointing relatively low-level officials to manage the search for relevant evidence and releasing the occasional confirmation of evidence brought to them by the U.N.


Two men lay a wreath on the monument marking the site where Hammarskjold and fifteen others died in a plane crash near Ndola in Northern Rhodesia in September 1963.
Two men lay a wreath on the monument marking the site where Hammarskjold and fifteen others died in a plane crash near Ndola in Northern Rhodesia in September 1963.

Two men lay a wreath on the monument marking the site where Hammarskjold and 14 others died in a plane crash near Ndola in September 1963. The only person to survive the crash, security officer Harold Julien, died nearly a week later from his injuries.  Daily Express, Hulton Archive/Getty Images

The air tragedy unfolded against the background of a bloody civil war that followed Congo’s independence from Belgium. The war pitted Congolese nationalists against a secessionist rebellion in the mineral-rich state of Katanga, which had the backing of Belgium, Western mining companies, European mercenaries, and the CIA. Hammarskjold was en route to Ndola in Northern Rhodesia to negotiate a cease-fire with secessionist leader Moise Tshombe. The United Nations sent peacekeepers into Congo, where they ultimately found themselves at war with Katangan separatists and European mercenaries, who were backed by Western mining interests.

A Rhodesian commission of inquiry found that the pilot had miscalculated the height of the tree line and plowed into the forest canopy. A subsequent U.N. inquiry could not establish the cause of the crash, leaving open the possibility that Hammarskjold could have died either as a result of an accident or foul play.

Eyewitnesses in the area recall seeing a small plane approach the Albertina before there was a bright flash in the sky and then watching the flaming aircraft plunge into the forest, instantly killing everyone on board except the delegation’s acting chief security officer, Harold Julien, who died from his injuries nearly a week later.

Before his death, Julien, a former U.S. Marine, “suggested a threat or attack as the plane approached Ndola, possibly involving a sudden explosion,” according to Othman’s reports. “This evidence was augmented in 2018/19 by information from Zimbabwe that showed that Northern Rhodesian authorities had tried to stifle those statements of Julien from being made public,” Othman wrote in his 2019 report.

Othman has cited documents indicating that British officials had intervened behind closed doors to persuade the U.N. to alter the conclusions of the report to rule sabotage or an external attack.

The case remained unsolved for decades, fueling conspiracy theories and inspiring generations of journalists, scholars, and other researchers. In 1992, two of Hammarskjold’s top advisors, Conor Cruise O’Brien and George Ivan Smith, wrote in the Guardian that they had evidence that their boss’s plane had been shot down by accident by mercenaries in the employ of Belgian, American, and British mining interests, which feared Hammarskjold’s peacemaking would jeopardize their business interests.

Goran Bjorkdahl, a Swedish national whose father worked in the region, began researching the U.N. chief’s death and conducting interviews with local charcoal-makers who had witnessed the Albertina’s final descent. Rhodesian and U.N. investigators at the time largely dismissed the testimony of local Black African eyewitnesses.

The case received a boost when Susan Williams, a British scholar who grew up in Zambia, revisited the crime, unearthing previously unseen documents from the archived papers of Lord Cuthbert Alport—who was the British high commissioner to Rhodesia in 1961 and who was at the Ndola airport on the night of the crash—including a secret report by Neil Ritchie, an MI6 agent who organized the planned meeting between Hammarskjold and Tshombe.

Williams’s 2011 book, Who Killed Hammarskjöld? The UN, the Cold War and White Supremacy in Africa, helped spur the establishment a year later of the Hammarskjold Commission, a voluntary body of international jurists and lawyers chaired by a British judge, Stephen Sedley. Williams has since fed documents to the U.N. investigators.

“The responses of the U.S. and the U.K. to Judge Othman have been appalling and arrogant,” Williams told Foreign Policy in an email. “But they are entirely consistent with the behavior of those states at the time of the crash, when Britain was the colonial and racist ruler of Northern Rhodesia (Zambia) and the U.S. was interfering in the process of decolonization in Africa.”

“Both the U.K. and the U.S. stated that all relevant information had already been made available,” she added. “But this was not true in either case.”

The Hammarskjold Commission concluded in its final 2013 report that “[t]here is persuasive evidence that the aircraft was subjected to some form of attack or threat as it circled to land at Ndola.” It also concluded that it “is highly likely that the entirety of the local and regional Ndola radio traffic on the night of 17-­18 September 1961 was tracked and recorded by the NSA [the U.S. National Security Agency], and possibly also by the CIA.”

These findings prompted the U.N. General Assembly in 2015 to adopt a resolution calling on then-U.N. Secretary-General Ban Ki-moon to create a panel of experts to examine the case and determine whether there was enough evidence to merit further investigation. Ban appointed Othman, who is expected to conclude his work in September.


Demonstrators with signs saying the USSR is responsible for the crash that killed Hammarskjold in front of the UN building in New York on Sept. 21, 1961.
Demonstrators with signs saying the USSR is responsible for the crash that killed Hammarskjold in front of the UN building in New York on Sept. 21, 1961.

Demonstrators hold signs claiming the Soviet Union was responsible for the crash that killed Hammarskjold in front of the U.N. headquarters in New York on Sept. 21, 1961. Gamma-Keystone/via Getty Images

At the time of Hammarskjold’s death, the United States and Britain had extensive intelligence assets in the region, including CIA agents and NSA surveillance capabilities. But much of what the U.N. has learned about U.S. activities in the region has come from independent researchers, private archives, or other governments. Othman has asked the United States to provide access to intercepts or other evidence of communications from Hammarskjold’s plane or other U.S. aircraft in the area at the time of the crash.

On the night of the crash, there were at least three U.S. planes, including U.S. Army and Navy attaches’ aircraft, equipped with state-of-the-art surveillance equipment at the airport in Ndola. One U.S. intelligence official, Charles Southall, recalled in interviews having overheard intercepts of a known European mercenary pilot, nicknamed the “Lone Ranger,” shooting Hammarskjold’s plane. The U.S. ambassador to Congo, Edmund A. Gullion, sent a report to Washington on the day Hammarskjold was killed stating that the plane “may have been shot down.”

“The historical record strongly suggests that Governments, including the United States, which had a presence in and around the Congo region at the time, may hold such evidence,” Othman wrote in an annex to his 2019 report.

But the United States has provided limited confirmation. For years, Washington denied that Paul Abram—a former U.S. Air Force Security Service officer who also overheard transmissions of an attack the night of the crash—worked for the United States, only acknowledging his links to U.S. intelligence after he furnished American officials with his government identification.

A spokesperson for the U.S. State Department said the United States takes Othman’s inquiries “seriously” and “shares his interests in understanding the circumstances of the death of Secretary-General Dag Hammarskjold.”

“Over the years, the United States has shared over a thousand pages of previously classified documents [with the U.N. investigator],” the spokesperson said, speaking on condition of anonymity. The Office of the Director of National Intelligence, the official added, “conducted yet another exhaustive search for U.S. intelligence archives and did not find any additional information that would shed light on the circumstances of Secretary-General Hammarskjold’s death.”

British and Rhodesian colonial intelligence officials were also intercepting communications, suggesting they may have pertinent clues buried in their own archives. Othman is seeking access to documents describing the activities of Ritchie, the MI6 agent, and other British officials who were tasked with organizing the meeting between Hammarskjold and Tshombe.

Othman also sought information about a Belgian mercenary pilot, Jan Van Risseghem, who had served in the British Royal Air Force during World War II and is alleged by a colleague to have admitted to flying the plane that brought down Hammarskjold’s aircraft. Pierre Coppens, a colleague of the Belgian pilot, asserted in the documentary Cold Case Hammarskjöld that Van Risseghem was known as the Lone Ranger.

In response to a request for comment, a spokesperson for the British Foreign Office wrote by email: “The UK Government has conducted a thorough review of all the relevant files held by our Defence, Diplomatic and Intelligence organisations and is confident all relevant information has already been shared with the [U.N.] Inquiry team.”

Before his death, Southall, who was an NSA officer based at a listening post in Cyprus in 1961, claimed he had picked up a radio intercept of what he believed was the cockpit transmission of a fighter pilot opening fire on Hammarskjold’s plane. “You could hear the gun cannon firing—rat tat tat. And he said, ‘I’ve hit it,’” Southall recalled in an interview for the same documentary. “‘There are flames coming out of it,’ and quite quickly he said, ‘It’s crashed.’ And that was the end of the recording, and we processed this recording and sent it off to Washington.”

Othman is also seeking information from the South African government about an alleged plot by a paramilitary group, known as the South African Institute for Maritime Research, to assassinate Hammarskjold by placing a bomb in his plane before it left the airfield in Leopoldville—now the Congolese capital of Kinshasa—en route to Ndola. In a March 2019 letter to South Africa, Othman said he understood that the South African government had located documents detailing the plan, dubbed Operation Celeste, but that those documents have never been shared with the United Nations.

The South African government did not respond in time to Foreign Policy’s request for comment.


UN Secretary-General Antonio Guterres
UN Secretary-General Antonio Guterres

U.N. Secretary-General António Guterres lays a wreath on Hammarskjold’s grave on April 22, 2018.FREDRIK SANDBERG/AFP via Getty Images

Wieschhoff and other relatives of the crash victims are hoping that the U.N. will step up pressure on the United States, Britain, and South Africa to open their archives.

“The UN’s effort, such as it is, creeps along and now enters its ninth exasperating year,” Wieschhoff wrote in the joint letter to Guterres. “From the outset, the search for answers has, in our view, been underfunded and understaffed.” Othman, he added, took on this formidable investigation “lacking a sufficient mandate and the Secretariat lacking a genuine commitment.”

“We also would have thought that by now you would have insisted that each of those governments present you or Chief Justice Othman with an action plan designed to promptly survey its archives and release all records bearing on the crash,” he added.

Guterres wrote back to the families: “I fully understand your grievances and will take them seriously into account for the future.”

“I wish to confirm to you my personal commitment to pursue the full truth of what happened on that fateful night in 1961,” he wrote. “We owe this to those who perished, and to you, the relatives.”

Guterres also said he was “encouraged by the progress” Othman has made over the years and would continue to do everything to help him carry out his work. But he made no pledge to personally press key governments, including the United States and Britain, to release all relevant documents in their archives.

Colum Lynch is a senior staff writer at Foreign Policy. Twitter: @columlynch

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