When just a new Army pilot, I was tasked with transporting a Brigadier and ADC down the east coast of OZ. Thought to stay well inland of the Evans Head gunnery range. 1500', 60 kts, and out my left window, approaching rapidly at the same level was a giant orange cylinder...from memory about 30m long and 6m diameter...with no visible means of propulsion. Slammed the collective down to see the "UFO" pass over the rotor head with maybe 50' to spare.
While trying to handle the overspeed, calm one very unimpressed Brigadier, and avoid having to change underwear, I saw a flash off a wing 2 miles away going in the opposite direction out to sea. Turned out the "UFO" was a target being towed by a Mustang 1500' above and at least 1 1/2 miles ahead. The Mustang was heading east when the target went over me heading west.
Turned out the day before he had taken out two rural power lines by getting too low!
Imagine if I had cyclic climbed instead of dropping the collective.