Our neighbour in Chilliwack, Gordy, had worked as a paramedic in the Yukon and had lots of stories.
They were driving their ambulance through a small valley on a nice clear day. They saw what they took to be an Airstream trailer approaching them way farther down the valley, but on the same road. They then realised that the trailer was actually on the other side of the valley, but there was no road on the other side. By this time they could see that it was not an Airstream as whatever it was, went silently past them, just above the trees, on the other side of the Valley.
The other story was of a friend of Gordy's who was a pilot. He told of a flight he made in which he claimed that it appeared that a mountaintop had disappeared (!) and in its place was a huge complex. He radioed it in and talked about it when his flight was over. A few days later he received a visit from the 'authorities' who warned that if he continued to talk about this, he would be considered delusional and would lose his flying license!
Not sure I could accept these stories, but would be interested if others had heard similar stories.