The Army Aviation Support Facilities in Stockton, California, is the home to a fleet of helicopters and the crew who maintain and fly them. I have a family member who works there, and he has told me that there are some peculiar things that occur in the building.
The first I heard of weird happenings at the facility was a few years ago, when I was told of a strange scent that workers were noticing. A woman had previously worked in "the shop" (as the employees refer to the aircraft maintenance building), but had left, and subsequently suffered ill health leading to her death. She was known for wearing a perfume with a particular floral scent. After her death, people working in the building began to report that they would smell her perfume. Initially, it was assumed that one of the other women who worked there had taken to wearing the same type, but this was quickly found to not be true. To this day, the perfume is still smelled every now and again.
My relative also reports hearing phantom voices in the aircraft hanger and attached offices. He says that the voices are clearly human, but always seem to be speaking at normal conversational levels in another room, and specific words can never be quite made out. Although most of the staff are willing to work alone in the building, the voices are spooky enough that they prefer not to have to. Following the voices to their source always reveals the location from which they were emanating to be empty.
Commentary: The Army Aviation Support Facilities is staffed by a mix of Army National guard members who work full time, civilian employees, and part-time National Guard members. Known for it's Chinook Helicopters, the facility has a seasoned staff of military veterans who have seen and done alot. So, naturally, when confronted with the supernatural, these rather tough individuals use the unnatural as a source for playing practical jokes on each other.
My relative tells me of times when various members will start to sniff the air, asking if anyone else smells anything, just to see how people act. Likewise, it's not unknown for someone on late-night duty to make noise and book it out of a room just to see if another person stuck with a similar responsibility will come running or become frightened.
Can I explain the hauntings? Well, the fact that these folks are playing practical jokes on each other probably explains quite a bit of it right there. I could probably come up with perfectly plausible explanations even without the practical jokes, but I have to admit that the fact that people are essentially living the folklore as a way of harassing each other amuses me, and I would be hard-pressed to discourage it.
Sources: Personal Account