It was almost 5 am when i heard a loud, plane-like noise coming from outside. it was too loud and to long to have come from any car, truck or bike from the street. it seemed airborne and had about the same duration as a plane would have. right away, i checked the flight radar and found that the most recent flight had arrived at 4:27am (aprox), which was around 20 minutes earlier. it would be unlikely to have come from any comercial flight. i am positive the sound was real, as i discussed it with my also present friend.