If you hadn't mentioned the story about your dad and how long ago that happened I would have guessed for sure it was a drone or something like that. I just don't think that kind of tech was available back then to do something like this. At least not outside of certain organizations. My mother in law experienced a segment of lost time when she was much younger, and while I believe her, she can't really give many details.
Yeah, no drones back then when my dad saw it and drones don't move at clean right angles or with the speed both accounts mentioned. Who knows what it was, not me and not those two people who saw it.
There's a lot of stories of people losing time segments...many don't have any explanation. Curious.
I'm smart enough to know that we don't even know a fraction of the mysteries of the universe, so I try to keep a pretty open mind.
Open minds are preferable to closed ones so you're on the right track I'd say.