Radar Operation ----- Page 9 of 12
As the radar antenna goes around it picks up the target ahead, and then as it passes the exhaust stack aft, it also picks up signals that bounced off the stack towards the target ahead and visa versa.
All the radar knows is the antenna was pointing towards your aft quarter and a signal was received so it painted a target on the radar screen aft of you.
If you don't see anything aft and the two targets approach each other on the display at the same rate of speed, it most likely is a indirect echo. Use caution until you are sure.
Indirect echoes can also come from nearby buildings, bridges or other objects.
