There are a limited amount of possible explanations, all which is eliminated as plausible by any one involved (air traffic control personnel, the pilots, military radar stations, meteorologists). It would be a leap of faith to conclude "aliens", but would it be a bigger step than concluding any hypothesis' already deemed implausible? (eg. weather balloons).
How about concluding "I don't know"?
That's a very good conclusion. I would be satisfied by just sticking to that.
That being said, having all sorts of pilots and radars report flying objects in the sky, crossing air space boundaries as they like, going close to both civilian and military crafts, really should provoke massive investigation and massive public awareness. It doesn't!
Recently I've been struck with a belief in Aliens being present on this Earth. It happened after I watched this documenary (and subsequently several others). My feeling of belief is not particular interesting in itself - I could be lunatic or otherwise psychological dysfunctional. What I'm interested in knowing is to what extend other people, who consider themselves rationalists, feel belief in the existence of aliens on this earth, after watching this documentary. Is anyone willing to try and watch it and then report back?
Another question arising in this matter is how to treat evidence of extraordinary things. Should one require 'extraordinary evidence for extraordinary claims'? I somehow feel that this notion is misguided - it discriminates evidence prior to observation. That is not the right time to start discriminating. At most we should ascribe a prior probability of zero and then do some Bayesian updating to get a posterior. Hmm, if no one has seen a black swan and some bayesian thinking person then sees a black swan a) in the distance or b) up front, what will his a posterior probability of the existence of black swans then be?