"that kind of thing simply can't be kept a secret"

Oh, sure it can. Anything can be kept a secret. Not that you can't prevent some people from talking about it or writing a book about it...but you can certainly prevent the authoritative mainstream from talking about it while they focus obsessively on bullshit like O.J. Simpson or Tiger Woods or the "Surge" in Iraq or whatever.

The public has a very short attention span. You just make sure it's occupied with other things most of the time...and it is.

The evidence is, in fact, absolutely overwhelming by now, but the mainstream authoritative sources (the military, the government, the mass media) simply don't bother recognizing it officially, or announcing it, and that's all that's necessary to keep it "a secret" (meaning it's not precisely a secret in the literal sense of the word, it's just below most people's radar, that's all).

I didn't see "landings". I saw flyovers, and they were not at 3 AM, therefore I gather they're not in Mr Vallee's data. ;-) God knows where he thinks he could get "all the landing data"...from whom, pray tell?

Astronauts, airline pilots, and leaders of countries have spoken about seeing what they believed were alien craft. It's NOT a secret, it's just not paid attention to or officially acknowledged by Big Brother and our the mass media. It's ignored 99% of the time by our mass media, and that effectively keeps it "a secret".

As I said, you're just believing what you want to believe. And so am I. And that's just fine. I don't talk about this stuff because I think it'll make any difference if I do, I just talk about it because I'm interested. Period.