As I wrote...

There were ellection nearby so they flight there because Smoleńsk was near Katyń (you know Katyń massacre done by soviets on Polish officers). Usual show with flowers on the graves etc, patriotic of course but important for politicans because of presidential campaign (other years they were not visiting Katyń). It was military flight, as Polish air force were transporting politicians in those times. Plane was Russian production TU-154, short time after renovations in Russia. As most military equipment in Poland - renovated old junk remembering soviet times. Those renovations of course mattered maybe,but junk is junk.

Already some cabaret did even prophetic sketch that there would be plane crash of "Polish air force one" (and joking about the comparison to air force one) half year before those plane crash in Smoleńsk in 2010.

Those day on Russian military airport (being in absolute shitty state - broken lightbulbs on airstrip, radar sometimes working sometimes not etc) were mist at the moment of landing because they started 1 hour late (president was late). It was nearest airport however. If they would land in Moscow president would be in Katyń near the evening. And I repeat - he needed photos from Katyń for presidential campaign.

The problem was earlier (2 years) when Georgia was fighting with Russia former captain and first pilot with range of major were criticized for not landing in Tibilisi, because there were risk plane would be shot, and were almost dishonourably discharged because president was pissed off as French president landed earlier.Man was called coward and other things were done to make his life shitty. At the end those guy left military. Simply it was about politician game and president showing himself as saviour of Georgia etc. Capitan of the flight to Smoleńsk was former subordinate of those major and his second pilot. Also they had all military commanders including general being chief of the air force on the board. Pilots had no legal permissions to land in such conditions they had. In theory and according to procedure capitain of the plane is deciding and responsible for plane safety. But because of those situation they had, those pilots were probably worried about their future. So they tried to land despite they shouldn't. Instruments not showed them how low they fly. There were even theory that chief of the air force were in the pilots cabin was sended by the president to make them landing or that call of the brother of the president (current boss of PiS party) were insisting on landing (those call is however top secret thing known maybe by some people in Pentagon),but even if not - they tried to land when they shouldn't do it. As the result Plane crashed - with them, president, whole general staff (yes,whole general stuff !!!) and many other VIP put irresponsibly to one plane.

PiS party were claiming it was assassination and claimed explosion or other way murdering people from those flight by Russians but had no real proofs. (Well some its supporters can believe it was assassination actually but minority).

Russians pointed at the end of investigation fault of the pilots.They were right about that,they shouldn't be landing. And ignored their own guilt about airport and doing renovations wrong.They did renovations wrong already:

Some instruments in second plane - as there were 2 in those transport regiment - were working bad,and engine were repaired in company linked to some Putin's friend. And while I think theory with assassination is bullshit those company were probably not respecting air industry standards. Those company was certified by russian MAK,those same institution which were allowed to do the investigation about plane crash - prime minister Tusk were from other party that president Kaczyński, and Tusk allowed russians do investigation according to Chicago convention despite it was MILITARY flight. Mistake or purposeful ? Who knows too.

Why those engine is important ? Official version claim direct cause were wing hitting the tree (birch). But from remaining record from flight recorder it was known (but not treated as important) that in one last moment pilots wanted pull up and gave full power to the engine. It was too late because of the tree really or "repaired" engine failed/or even exploded after giving full power ? We will probably never know...

Whole those disaster was later used by PiS - current rulling party - as fuel for their political campaign for years. The result of those accusations were the wreck were never returned (because clearly if it would be returned that would be used to fuel those claims about assassination or it would give some unwanted clue about crash)

Less known but important thing also were problem because of the phones.Some phones were using already some NATO encryption standards or something like that and Russian intelligence stole it from the crash site because they got occasion.

Why it is all important really ?

Clearly it was radical example of those important problem of Polish military - too big influence of politicians over it and too big influence of politicians over the soldiers (especially those higher rank),advancing process etc.