So there could be a lot of possibilities. . . . . . . . . . . . . . . . . . . . . . . . . . ., . . . . . . . . . . . . . . . . .
Some UFO sightings are those of real alien spacecraft. I may not know quite for sure if they are spacecraft, but the fact is that people have witnessed many spacecrafts before. They may be real for all I know, or fake. Deep inside, I really believe that there really are UFO sightings and evidence that we are not alone and that spacecrafts really exist in our universe, perhaps even in our solar system.
I believe it is reasonable to assume that some UFO sightings are those of real alien spacecrafts. UFO sightings are reported by many different people but I feel those that come from military personnel and upstanding citizens with public backgrounds are the most interesting and thought provoking. I believe it's very possible and I believe some governments are aware of it and keep it a secret from the general public.
I think the majority of UFO sightings are fake and either explainable by weather anomalies or Chinese lanterns or just regular air crafts or perhaps experimental air crafts. But, there are some that can't be explained. And with the chance that there's intelligent life out there, it would make sense that they observe other planets the same way we observe wildlife.
The saucers are usually telepathic even. I have done the science they have me and in conclusion believe the wholeness of what they have stated to me which in conclusion is that they are extraterrestrial in nature. I have also met with beings proclaiming to be extraterrestrial in origin and have no reason to think they would be lying to me.
There are many things that could contribute to the sightings of ufo. Innovative secret military craft like the stealth bomber could easily be mistaken for align craft. Fireballs or lightening balls are a phenomenom that also can be mistaken for alien craft. Thirdly, strange mirages of far away objects are warped to look like strange objects in the sky (this can account for other mysteries too like ghost ships and Nessie the loch Ness monster. Finally, hoexes. It's relatively easy to fake a footage with today's technology and cunning.
In against the likelyhood of alien aircraft sighting I propose that surely alien aircraft would be spotted and caught far more often by satellite imagery, military radars, and commercial flight passangers/staff.
No, I do not think that some UFO sightings are those of real alien spacecrafts, because if there really were aliens, they would have made themselves known by now. Aliens wouldn't get close enough to us to be in our atmosphere to just decide not to land. If they really existed, they would have wanted to have met us by now.
We've seen , heard, and watched a lot of movies and news in TV, radio, and read it at news papers about UFO sight seeing. But non of them are true because there has never been any actual perceptible evidence behind that. Scientist have been long trying to prove another form of life like UFO or alien space crafts exist, but they have never been able to prove that evidence and this is why the answer to the question whether UFO sightings are those real alien space craft is NO from my point of view. All of these sightings have never been proved that they have been a real UFO or another form of life but earth to get to the logical point to distinguish whether that air craft belongs to aliens or not.