Large (200') black triangle craft with white & blue lights & plumbing like under structure flew at 350 feet . Loud tonal/buzzing

Van Nuys, Calf. Second or third saturday evening about 10 pm in august of 1983. I was home alone, no other neibors came out. First I was indoors and heard a strange plusating, swirling sound, it could be heard for a distance of a mile buzzing like a electronic keyboard/organ with all the keys depressed, not a combustive sound. Flew at a speed about 15 MPH at a height of about 350 feet. Pipes, holes and waffle impressions underneth. Blue and white lights seemed to bounce independently, lighted the driveway I was standing on. Each of the three sides were about 300 foot edges. I was standing right beneth it and I was over taken with a sensation of awe. after it was out of sight and sound I phoned the nearby airforce post at Van Nuys airport, the direction it came from, (moved eastward) an officer put me on hold indefinetly.  2 years later, it was mentioned on a local TV program (EYE ON LA) by witnesses on a nearby moutain, 2 or 3 miles away. 4 years after, I met one other Van Nuys resident who also saw it that same night and over head as well.
Date is approximate.  PD