Grandma's UFO

It was large. It hovered about 100-150 feet above the ground. It made no noise. It had lights on each of the 3 corners. It was a dark non-shiny, metallic colored craft.It was hovering in the path used by small aircrafts to land and take off at the small airport about a mile away.Above and slightly to the East is the flight path of aircraft going between Ft. Vancouver and Ft. Lewis. As Kids we would stand in the yard and watch the planes streak by overhead and count the sonic booms. The lady that saw this was born in 1903 and is now deceased. She was not one to watch TV. She was not one to make up stories. She did however have insomnia. She related more details to me but since I have been ill I can't remember them. While I have mostly recovered my memories have not. She was tired for a day after that and not really willing to admit to what she had seen. It seems she said there were other lights on it like a big window.  She got the feeling that they were watching something and did not notice her watching them.
Date is approximate.  PD