A large red light between 400ft agl. and up,erratically moved in all directions and at varing speeds. A smaller green light departed from the red light, moving quite erratically through the sky,while the red light remained stationary.I am an Aviation Safety Inspector with the FAA.On Sept. 15,1998 at 11:30pm a friend called me to say that she really believed that she was watching a UFO from her waterfrount home,near where I live. I went outside and did not see anything. I then drove down to the boat harbor down the street where I observed a large red light moving very erratically across the sky. It was utterly silent. The light varied in altitudes, the lowest point being approximatly 400ft agl.The red light became stationary and a smaller green light emerged from it and moved in an almost grid like pattern,moving quite fast. The red light remained stationary while the green light moved in all directions around it. This lasted for 40 mins. The green light then dissapeared in what appeared to be in the red light. The large red light then shot straight up in the sky with a right hand trajectory The night was clear, calm and about 40 degrees with a multicipy of stars.