On my flight to Sydney Australia.

on a Qantas 747 flight.  Half way Through our flight, the captain speaking over the P.A.System. This is your captain speaking, look out the right of the plane you will see a UFO.
I ran from the back smoking area, I was sitting at the left window seat, ran across the center row of seats walked quickly left I walked swiftly towards, just behind the right wing. I looked out the window at the 5th seat back , everyone was looking out the windows, yelling out, look at that, oh my God!  Just 50 feet below us, was a disk like sauser at least 4 times larger then our 747 right wing. The saucer flew underneath us just about 3 miles per hour faster then us, traveling at 11:oclock direction, everyone had a great top side view of the top side of a UFO saucer, raised slightly from the edges to the top center. No windows visable.
I didn't see any seams or rivets,as it flew past us, it looked as if it was punch pressed out. from a press. The color looked to be Grey like silver and aluminum. On my arrival in Sydney, at my hotel I synchronized my watch to local time by radio broadcast, the news was reporting my flight number to have seen a UFO.