Wavebreak Media/Thinkstock(NEW YORK) —  The premise of ABC’s most talked-about new show, Designated Survivor, is an unthinkable attack on the United States that wipes out the president and all of the country’s top leaders except for one – the designated survivor.

Although the show is fiction, it uses real-life federal government protocols for its plot lines. However, a similar devastating scenario did happen to one European country that is still investigating its cause.

It was a quiet Saturday morning in Warsaw in April 2010 when President Lech Kaczynski boarded Poland’s equivalent of Air Force One with a number of top Polish government and military officials, including Poland’s version of the Joint Chiefs of Staff, several secretaries and cabinet members, and took off on a flight bound for Russia.

“I knew 80 percent of the people on board,” said former Polish Minister of Foreign Affairs Radek Sikorski. “They included generals that I appointed. They included my deputy, Andrzej Kremer, the head of protocol of the foreign ministry.”

 They were on their way to Smolensk, near the site of the notorious Katyn massacre of 22,000 Polish officers by the Soviet Army during World War II. After decades of depredations and deceit, the Russian government was finally acknowledging the tragedy and Polish officials were going there to commemorate the event.

Sikorski was invited, but couldn’t make the trip. On that Saturday morning, he was having breakfast with his mother when his phone rang.

“I get a call … that there was something wrong with the presidential plane,” he said. “So I made several calls in succession. First to the prime minister to alert him. He wasn’t available. I talked to his wife. Then to the operations center of the foreign ministry to start investigating.”

When parliament member Jerzy Wenderlich heard something may have happened, he said he tried calling his colleagues on the plane. Their phones rang over and over, he said, but nobody answered.

“And then one moment, this ring[ing] stopped,” he said.

Soon news spread that the plane had tried to land in dense fog and crashed into a tree in Smolensk, Russia. Polish journalist Wiktor Bater was near the scene, preparing for a live broadcast of the commemorative ceremony, when he received confirmation that the crash had killed all 96 people on board.

“Nobody is alive. Everybody is killed. It’s a horrible crash,” Bater said. “And in one moment, Poland’s state without a government, practically.”

Deputy speaker of the lower house Jerzy Szmajdzinski was on the plane. His wife Malgorzata found out he was dead from watching TV reports of the crash.

“It’s an unimaginable shock,” she said. “I shouted to my daughter, who was still asleep. She ran downstairs. We both collapsed with grief.”

The scene around the crash was chaotic.

“Between our diplomats in the airport, it was really a huge panic. They didn’t know what to do,” Bater said. “In Warsaw, it was a very huge panic too. Who should be the president in that moment?”

Sikorski, Wenderlich and most of the surviving members of the Polish government raced to their offices in Warsaw to grapple with the unprecedented crisis.

“I got through to the Speaker of Parliament and we decided to do what we could, which is to say the prime minister called an emergency session of the cabinet,” Sikorski said.

 Within days of the crash, the flag-draped coffins of the Polish president, his wife Maria and the other government officials were brought home to Warsaw. The streets were lined with mourners as the country added another painful page to its harrowing history.

“It was a terrible shock,” Sikorski said. “And a sense also that while Poland has been doing so well over the previous quarter of a century, bad history caught up with us. It brought out all the fears of our tragic history to the surface.”

There were some questions about whether the young Polish democracy, just 20 years unyoked from communist rule, could withstand the shock, and yet, the state remained stable. The trains kept running, the ATMs kept working and most importantly, Jerzy Wenderlich said they had a clear line of succession established in their constitution.

“The constitution worked in this horrible time with great precision,” Wenderlich said.

In accordance with the law, the head of parliament, Bronislaw Komorowski, assumed the office of the president. Even though he was from the opposition party of former President Kaczynski, no one objected.

“We felt that the country needed reassurance that the government was continuing and that we will come through this,” Sikorski said. “So in that sense we were torn between our emotions and our sense of duty.”

With so many leaders killed, many top government positions had to be filled. Wenderlich found himself thrust into the role of deputy speaker of the lower house, formerly held by Jerzy Szmajdzinski.

“On the outside, I projected myself as confident,” said Wenderlich. “But inside I was having this conversation with myself that there are many things I need to learn.”

Watching her husband’s position be filled was also difficult for Szmajdzinski’s wife.

“Emotionally, it was hard,” Malgorzata Szmajdzinska said. “However, from the political point of view, the transition was actually quite smooth.”

 But soon after the country started to repair itself, questions were raised about how the president’s plane crashed in the first place.

“We know what happened because we have the tape from the black boxes on which you can hear the warnings of the system, that there is terrain ahead and pull up,” Sikorski said. “But in the end the pilots allowed the plane to go too low and they hit a tree.”

ABC News aviation consultant Stephen Ganyard says numerous investigations have confirmed that the plane was ill-equipped to land in fog and that the airstrip at the Russian airport where they were headed wasn’t certified for such a landing.

“If the weather had been even halfway decent, it would have been fine,” Ganyard said. “Because the ceilings were so low, the visibility was so low, it made it almost impossible for this airplane to land.”

Ganyard said the pilots were also under immense pressure to land the plane regardless of the hazardous conditions. On the cockpit recordings, Ganyard said, “They had somebody come into the cockpit and tell them, ‘The president will go crazy if we don’t land here.’ So this crew is under incredible pressure to land the airplane even though they knew that it was unsafe and they had very little chance of doing so safely.”

“It didn’t need to happen this way,” he added. “This was a totally preventable tragedy.”

The implied negligence and recklessness stained the memory of the dead president, who was the one who decided to make the trip and have most of his top officials with him on the plane.

“It was the worst organization you can imagine, of course,” said Bater. “But it was only the decision of our President Lech Kaczynski.”

But Poland soon turned their anger toward Russia.

Journalists at the conservative newspaper Gazeta Polska have devoted their attention to the theory that the Smolensk tragedy was no accident, but an act of terrorism devised by Russian President Vladimir Putin to assassinate a regional rival. The Kremlin has denied these accusations.

“You don’t remember the Russian common practice of murdering their political opponents? And Kaczynski was such a great opponent to Putin,” said Gazeta Polska’s Rafal Dzieciolowski.

The newspaper says the proof is in a video seeming to show Russian responders tampering with the plane’s wreckage. There were also questions about missing debris, disputes about the ability of a single tree to down a large plane and claims that the Russians tampered with the cockpit voice recordings.

“But nobody has yet produced a consistent story alternative to the official report that would make the evidence fit into a logical sequence of events,” Sikorski said.

Lech Kaczynski’s Law and Justice Party continues to examine the tragedy, running on a platform of promising to reopen the case and finding the truth. As a political tactic, it worked. Law and Justice won the 2015 parliamentary election. Jaroslaw Kaczynski, the former president’s twin brother, is now the party’s leader.

Every month, mourners gather at Warsaw’s largest cathedral to commemorate the Smolensk tragedy. The service is followed by a political rally for the Law and Justice Party.

“One-third of the Polish people still believe that this airplane was either an assassination or a terrorist attack,” Ganyard said. “There is no scientific evidence. There is nothing to point to that being true.”

Researchers have been aiding the conspiracy by devoting countless hours to the case, in addition to documentaries and even a recent movie released this year called, “Smolensk,” which focuses on the theory that the plane was brought down by a bomb.

Defense Minister Antoni Macierewicz is heading a new commission to investigate the case and prosecutors appointed by the government ordered the remains of 83 of the 96 people who died in the crash to be examined. Just last week, the bodies of Poland’s former president and his wife were exhumed.

Today, many of the dead are interred at Warsaw’s military cemetery. But it may be a while before they can rest in peace.

Watch ABC News’ 20/20: The Real Designated Survivor on Wednesday, Nov. 23 at 10 p.m. ET.

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