David Fravor, who I believe is the Navy Pilot that is the public face of the "Navy tapes" you are referring to, described the object as a "Tic Tac" - which is c

David Fravor, who I believe is the Navy Pilot that is the public face of the "Navy tapes" you are referring to, described the object as a "Tic Tac" - which is cylindrical. Still, I'd bet on some experimental (or just rare) type of human/American aircraft. Second place theory is that a pilot is making a joke or resigning or something, similar to how a developer might open a sev-1 ticket to tell his soon to be former company that he is resigning. (Although, hopefully "mischievous prankster" is an attitude that is heavily discouraged among commercial airlines pilot)