UFO Sighting in Pittsburgh, Pennsylvania on April 9th 1999 – was watching what i thought was a plane flying when all the sudden it zipped off at incredible speeds

I was in my late teens and was sitting on the steps at the back door of my families house when I noticed what I thought was an airplane it was silver reflective shiny almost but still it was so far away I just assumed it was an airplane at that point it did something incredible it was flying at a steady pace when all the sudden it accelerated to a speed I've never seen another aircraft achieve in a fraction of a second it zipped off I've never told anyone but my wife about this experience and it changed my life profoundly I had to know whether or not we are alone in the universe i watched every show and read every book on the subject of UFOs I'm still not sure what it was but it couldn't be from earth