This is 2016 - planes don't just fall out of the sky.
Mr Gardner may be jumping the gun a bit
in that 0600 comment/twitter quote(??), but he is cited with a more measured analysis that gets at security and "we don't know yet." (I'll side with mockingjay on "fireball?" with MH370 as a reference).
EgyptAir flight MS804 from Paris to Cairo crashed - Hollande - BBC News
I noted on the BBC link that included the sound byte that the French authorities are (reportedly) already investigating the ground crew at CDG.
Sadly, contra the little quote, planes do sometimes "just fall out of the sky." In the not too distant past ... AF 447(upset) Air Indonesia(upset) , Air Algerie(upset), Germanwings(Upset FO, and it flew down rather than fell), Metrojet(bomb?) and so on. But in the larger sense Mr Gardner is correct. Flying is still a very safe way to travel and planes generally don't just fall out of the sky. Embedded in that little bon mot is a core point -- there's a reason for the rare and tragic events like this. Confident that the reason will be found in due course. I heard about this crash on the radio this morning ... plane missing between Paris and Cairo ... seen descending by Greek radar ... (I thought, jumping to a conclusion, shame on me, A320? OCF?) ... later heard it was A320 ... a bit later logged on to PPruNe to see what folks have so far. Thanks for realigning my brain, all and sundry: look at the conclusion I jumped to from a brief radio report?
Regarding the posts from folks covering maritime search efforts: thank you.