If you have never heard of it, here is a refresher. Quoted from the page:
The 2010 Polish Air Force Tu-154 crash occurred on 10 April 2010 when a Tupolev Tu-154M aircraft of the Polish Air Force crashed near the city of Smolensk, Russia, killing all 96 people on board. These included president Lech Kaczyński and his wife Maria, former president Ryszard Kaczorowski, the chief of the Polish General Staff and other senior Polish military officers, the president of the National Bank of Poland, Poland’s deputy foreign minister, Polish government officials, 18 members of the Polish parliament, senior members of the Polish clergy, and relatives of victims of the Katyn massacre. They were en route from Warsaw to attend an event marking the 70th anniversary of the massacre; the site is approximately 19 kilometers (12 mi) west of Smolensk.
In brief, the crash occurred in poor visibility due to heavy fog. The plane flew too low in landing and crashed into some trees. Conspiracy theories are of two main types: Most popular: Anti-Russian. Russia blew up the plane with explosives in order to kill the Polish President and much of his government. Also revenge for Poles continuing the play up the Katyn Massacre. The people spreading this nonsense are Polish anti-Communists often associated with the armed Polish anti-Communist resistance that fought in Poland from 1944-1956, Russophobic, rabid, crazed members of the Polish government, lunatic Russophobes the world over, far rightwing nutcases and of the course, the US CIA. There is absolutely no evidence for this conspiracy whatsoever. The Russians are not so insane as to do something like that. They are not that nuts. Further, the Polish President killed in the crash was one of the few Polish Presidents who has not been a crazed Russophobe. He refused to side with NATO in their war against Russia. He obviously could not side with Russia either, but he did adopt a neutral stance in the NATO-Russia conflict which made him widely hated in the West. In other words, he was Russia’s best friend. So Russia killed their best friend. Right. Much less popular: NATO shot down or blew up the plane in order to kill the neutral Polish President. There is even less evidence for this one, and anyway, if it were true, the Russians would have figured it out right now and would have blown the whistle on the West. Crazy: Among the Lunatic Conspiratard Sphere of the Web, many a crazed theory has been offered up. One of the choice ones is that the entire crash was faked (By whom? By the West? By the Russians? By both operating together? Why?), none of the people on board were killed and in fact everyone is alive and well. Yet none of the folks on the plane have been seen anywhere on Earth since the crash. We haven’t even seen their ghosts. Where are they hiding and why? This will be part of series where I will periodically look at conspiracy claims to see if there is something to them. I will try to blow the whistle on as many fake conspiracies as I can (and there are many of them).