I had been living at an airport that my parents managed for the city.I was about sixteen at the time,one of my duties was to put our training aircraft and our charter twin in the hanger at the end of the day.Twilight would best describe the visual conditions.After putting the single engine trainers in the hanger I was preparing to put the twin engine airplane in.(Cessna 310)I happened to notice movement in the lower horizon off to the east,(The hanger doors have a southern exposure)I observed four or five opaque disc,s in a single north/south line traveling westward,they disappeared from sight as they reached the western horizon.This took approximately less than a minute.I could not make out any identifying characteristics but I believe they were fairly high,and about three inches in diameter.It is difficult to judge size as one dosn,t know the altitude they are at, There were no contrails nor lights of any kind or any sound.I had lived at the airport all of my life and was familiar with many aircraft,Whether this was one object with multiple lights or four or five separate ones is difficult to say with any certaincy.But due to the spacing I,m inclined to say the disc,s were seperate objects.The sighting of these opaque disc,s got my attention because there wasn,t any type of navigation lights,nor rotating beacon lights,then as I listened for the sound of engine noise,thinking I should be able to hear something,but nothing was heard.From what I can remember they crossed the horizon a lot faster than any aircraft I had seen.At the time I thought it might be a ufo but was reluctant to say anything for fear of ridicule,I have 7000 hrs ,most in charter or corporate aircraft ,The largest I have flown is a lear and I have 1000hrs in those.(24,25,35).I am currently working as a aircraft mechanic for a major airline.I have never seen anything since that approximates what I saw and have never spoken to anyone who saw anything similar.