Tragic events may cause national trauma, especially when they are not solved. Hardly anything that has happened in any other country can be compared with what happened to Poland in 2010, when a Polish plane crashed outside Smolensk in Russia, killing the Polish president, his wife and 94 other people, including the whole military command of the country.On November 4, 1995, prime minister Yitzhak Rabin was murdered at a peace rally in Tel Aviv. In this case the murderer, a Jewish right-wing extremist, was immediately apprehended and has been sentenced to life in prison. The repercussions of the murder, however, are still felt in Israel. A promising peace process was derailed and has not gotten back on track since. The incitement inside Israel against “leftist” peace proponents has continued unabated.But all of this seems to pale compared to the Polish trauma. Already forgotten by many in the West, the Smolensk air crash deepened existing political divides in Poland and has lingered on as an open wound. The official air accident investigations by the Russian and Polish authorities have been criticized for a number of shortcomings and unanswered questions.A large part of the Polish population doubts the conclusions. Such a climate leaves room for speculation.What makes the crash so painful for Poland is its connection to the Katyn Massacre of Polish officers during World War II. The plane that crashed was en route to commemorate the 70th anniversary of the massacre.During WWII and for many years after the war, Nazi Germany was believed to have committed the Katyn Massacre. The truth became known only after the end of the Cold War.In the Molotov-Ribbentrop pact, the Soviet Union and Nazi Germany divided Poland, Ukraine and the Baltic countries. WWII broke out with the invasion of Poland on September 1, 1939, by Nazi forces and on September 17, 1939, by Soviet forces. The Soviets took more than 100,000 Polish prisoners of war. They released the men and kept the officers.According to Timothy Snyder in his horrifying book Bloodlands: Europe between Hitler and Stalin, the officers were brought to three camps. They thought that they would be allowed to return home. But Stalin and his secret police chief Beria had condemned them to death on trumpedup charges that they “would enter actively into the battle against Soviet power.” In a forest called Katyn outside Smolensk - the most infamous killing field - 4,410 prisoners from the camp in Kozelsk were shot.Snyder writes that altogether 21,892 Polish citizens were killed in this “lesser Terror.” In the Great Terror in the ‘30s, 60,000 Polish people in western Belarus and Ukraine had been sent to special settlements in Kazakhstan. The vast majority of the victims in 1940 were Poles by nationality.But as Poland was a multi-national state, with a multi-national officer corps, many of the dead were of other ethnicity. Some eight percent were Jews, corresponding to the proportion of Jews in eastern Poland. Germany was held accountable for the Holocaust and has repented.The Katyn Massacre has become a focal point for the countless number of Poles who were murdered by the Stalinist regime. Russia of today needs also to come to terms with its history during Stalin.For the families of the killed Polish officers, the years until 1990, when the full truth finally was disclosed, were long and painful. They have received neither apologies nor reparations. Without being able to mourn their dead, they were hardly able to move forward in life. Without an apology the relatives are still struggling.The relatives have every right to remember and commemorate those who were executed in Katyn and other places. So have also the relatives of those who were killed in the Smolensk air crash. Instead the aftermath of the air crash and the handling of the investigations opened new wounds in Polish society. The air crash was the biggest tragedy in Poland’s modern history after the fall of the iron curtain and became politicized from the very beginning.The internal division in Poland was already visible before the crash when the then Polish prime minister Donald Tusk from the Civic Platform Party (PO) traveled to Russia to participate in a separate ceremony on April 7, 2010, in memory of the Katyn Massacre. Three days later the Polish president Lech Kaczyski from the Law and Justice Party (PiS) traveled to Russia for another memorial service. The presidential plane, a Tupolev TU-154, crashed in the morning of April 10, 2010, in an attempt to land at the Severny airport in Smolensk or perhaps to find another airport because of the fog that morning.What really happened is disputed in Poland.Had the plane been properly maintained? Did the plane really try to land or was it doing a “go around” to look for another airport? Which instructions did it receive from the flight control tower? What was the cause of the crash? Why were no autopsies of the victims carried out? Why was there a ban against exhumations? The bodies of the victims were treated disrespectfully by the authorities who also misidentified a few of them. This of course caused great anguish to the relatives. The body of Anna Walentynowicz - known as the “The Mother of Free Poland” for her brave role in the Gdansk shipyard strikes - was identified in Moscow by her son but the wrong body was buried in Poland. To this date no-one knows where her remains are No joint Polish-Russian investigation was carried out. Nor were international air accident experts involved in the investigation.Immediately after the crash, the Russian Interstate Aviation Committee was tasked to investigate the accident, with some participation of Polish prosecutors. Its report was published in January 2011, without paying much attention to the Polish remarks.The independence of the Russian committee has been questioned by the European Parliament. In a joint resolution from March 2015 on the state of democracy in Russia - supported by all major political party groups - the parliament underlined “the fact that the level of dependence of the Russian judiciary on the authorities undermines any impartial and honest investigation.”The European Parliament also called “on the Russian authorities to immediately return the wreckage of the Tu-154 Polish Government aeroplane and all of its black boxes to Poland” and demanded an “international and independent investigation into the causes of the crash of the Tu-154 Polish Government aeroplane.”Poland carried out its own parallel investigation, published in July 2011 and named after its chairman Jerzy Miller, the minister of interior.The Miller report differs from the Russian report in some aspects, particularly in the identification of the actions by the Russian air traffic controllers and shortcomings in the condition of the Smolensk airport. It’s not clear if it had full access to the remains of the wreckage, which had been stored by Russia under unsatisfactory conditions, and the black boxes and recorders which had been found. Different copies of the recordings seem to have been circulating.However, the two investigations agree on the cause of the crash.According to them, the crash was caused by the crew because the pilot, pressed by the passengers to land, descended too low at excessive speed in a fog that prevented visual contact with the terrain. This led to collision with a birch tree, causing the plane to lose part of its left wing. The aircraft became uncontrollable and finally crashed.Up to half of the Polish public has no trust in the official investigations.Overall, trust in the government and the parliament is low in Poland compared to the average in EU according to the latest EU poll (Eurobarometer 83).The Russian investigation has been faulted for several strange measures in securing the crash scene, moving around debris and handling the wreckage. A Polish independent parliamentary commission was established, chaired by Antoni Macierewicz, a known politician, and assisted by an impressive number of scientists, academics and engineers from Poland and abroad.According to its findings, the plane received misleading information from the control tower. The crew did not try to land but to carry out a go-around maneuver when it was hit by on-board explosions. The parliamentary commission is of the opinion, based on its pool of experts, that the official description of the plane’s route during the last minute cannot be correct and that collision with a tree could not possibly have caused the plane to crash.Who are we, or rather the Polish people, supposed to believe? The two rival political parties in Poland, the Law and Justice Party and the Civic Platform Party, disagree on the cause of the crash, relying on different investigations and questioning the competence of the experts of the other side.The crash decimated the leadership of the Law and Justice Party and it took some two years for the party to rebuild itself. The Civil Platform Party won the parliamentary elections in June 2010 and has ruled Poland since then.New elections are due on October 25.According to opinion polls the Law and Justice Party is expected to return to power. It has already regained the presidency when Andrzej Duda, who worked with Lech Kaczyski, was elected last May.What Donald Tusk, now president of the European Council, might learn during his visit in Israel is how national disasters and wars are investigated in Israel. Despite the political divides and tension, Israel seems to have a tradition in establishing unbiased investigations and commissions of inquiry conducted either by the State Comptroller’s Office or Knesset, whose reports and conclusions generally are trusted.For Israel it is a necessity to draw lessons from what happened and to prevent similar accidents, mistakes and failures from occurring again. It must also prove to the outside world that it can investigate itself without being subject to outside investigations.In the Polish case, an international review of the investigations of the Smolensk air crash, as to whether they were conducted according to international standards, might be the best way to restore trust in the new government following the elections in October.The author is a former official at the European Commission.