Clockwise or counter-clockwise?
I’m referring to the display, the stereotypically green circular sweep thing with pings and bips. We’ve got a mock-up that goes counter-clockwise and it’s bugging people, but no one knows for sure.
Oh, and if it’s not always one direction, what’s the most common in the United States?
It goes CW in the Northern Hemisphere and CCW in the Southern 
Actually, there’s no physical reason why it can’t go either direction, it’s just that people are used to things going clockwise, so they usually do…
In my navy school days, the systems I trained upon (SPS-10 and -49) usually went clockwise, but could go in either direction as you desired.
I’ve stared at many RADAR displays throughout my career and every one of them swept clockwise. A CCW RADAR display would probably drive me insane in a very short amount of time, but I’m weird like that.
Some sonars don’t do a 360° sweep. They bounce back and forth over a small sector. Those will drive you crazy in a hurry.
Our aircraft are fitted with search radars that have a 360 degree clockwise sweep* and weather radars that scan back and forth across a 120 degree sector.
- They actually rotate fast enough that you are not really aware of the sweep.
In my Army days the air traffic control radars all rotated (when they rotated, that is) clockwise. During final approach the rotating dish swept back and forth, and then a second, vertically elongated would bob up and down, and the display would be split between course and glide path. Really, really cool for a radar with serial number 2 built in 1943.