Just to play devil's advocate-
If a final report states: "Adam Lanza went into that school armed with a pistol and a rifle and killed those people."  True statement?  Most of us would say, "yes."  But if the police knew through forensics that the rifle only fired 3 shots (pick a #) before the firing pin broke and that all the other shots came from the pistol, is it still a "true" statement?  Yes.  But it suffers the "sin" of omission.  It is true but not the actual truth.  And if the forensic reports are sealed to prevent the exposure of such information to the public for political reasons, hell, ANY reason...  Coverup.  Do you agree?

If a Navy ship fires a missile everyone on that ship knows they fired, and you can never expect a .mil to keep a secret.. The Navy had nothing to do with it... But I do believ it was shot down by probably the Iraqi's and Billy boy wanted it kept quite so he didn't have to bomb Iraq... If you  remember it was in the same summer as Kobar Towers and the Olympic bombing... So he did want anymore incidences of terrorism on his watch..
Read the book the Third Terroist about OKC, if you want a Gov cover up..

You can really never expect any group of people larger than one to keep a secret.  That's the best part of these stupid conspiracy theories. They assume the US Government is so competent and flawless that they can keep a secret as big as this one without a single leak of a single shred of evidence for their whack-job theories.  

Or you initiate a coverup, count on a large number of individuals to toe the line after the "gents, this is classified 'Secret'" discussion, put out an official narrative, and label those who come forward as conspiracy theorists and nutjobs knowing that the majority of the general public views the government as an infallible protector?

ETA:  I don't think our government dropped the plane.

I'm wondering why this thread has gone on so long.  Anybody with an IQ above room temperature should know better.  I mean it should be a well known that a spark from somebody simply brushing back their hair their head can create a spark that can start an oil well explode.

On the other hand it surely explains why Obummer & Company were re-elected.