I'm on Flightradar24 right now watching a line of planes from Japan/SK heading up to Anchorage Alaska over the Pacific. The fastest one is a UPS 747-8F listed as going 772 MPH (671 Kt) at 33,000 feet. I didn't even know that was safely possible for a commercial aircraft. Do you think it's a mistake, or do you think it's pretty accurate for Flightradar24? EDIT.....no joke....it had a black line behind it and now it's just dropped off the radar.