I did see a shadow of a large plane once and could not locate the plane it was created by. However, I was driving and could not really look as
carefully as I wanted to, and so presumed it must be somehow out of my line of vision.
Your post makes me wonder. My own experience was "odd" enough that I remembered it, but I justified it in my own mind by assuming it must be out of
my line of sight.
Considering that science is hard at work on a "cloaking" technology, and we know it is possible, your story makes me consider the possibility that
perhaps they are further along in the work than we know.
news.bbc.co.uk...
Researchers in the US and Britain have unveiled their blueprints for building a cloaking device.
www.cosmosmagazine.com...
PARIS: The age-old fantasy of rendering objects invisible took a sharp step toward reality Sunday when scientists said they had created a material
that can bend visible light in three dimensions.
Or, another ATS-like possibility,

there has been much speculation that 2008 will be "year zero" in terms of time travel. Because of the firing
up of the supercollider. This is from my favorite science mag, but unfortunately they only open the entire article to subscribers. But you will get
the point.
www.newscientist.com...
AS YOU may have heard, this will be the year. The Large Hadron Collider - the most powerful atom-smasher ever built - will be switched on, and
particle physics will hit pay-dirt. Yet if a pair of Russian mathematicians are right, any advances in this area could be overshadowed by a truly
extraordinary event. According to Irina Aref'eva and Igor Volovich, the LHC might just turn out to be the world's first time machine.
It is a highly speculative claim, that's for sure. But if Aref'eva and Volovich are correct, the LHC's debut at CERN, the European particle physics
centre near Geneva in Switzerland, could provide a landmark in history. That's because travelling into the past is only possible - if it is possible
at all - as far back as the creation of the first time machine, and that means 2008 could become Year Zero: a must-see for the ...
So, maybe they have the technology for full cloaking in the future, but they cant cloak the shadow, and so they made their sightseeing vehicles in the
shape of a current passenger plane so they can tour us without scaring the hell out of us.
Just some speculation.