@Booglebox
no, you can't log anything.
Clearly it's against the regs for me to watch a plane fly overhead and for me to log the time.
Clearly it's against the regs for me to log time while sitting in the back seat of a 4-seater.
And clearly, it's against the regs for me to log time when I am NOT a required member of the flight crew.
If, however, the pilot is flying "under the hood" AND I am qualified and rated and have current medical and all of that for the plane, and I'm in the front seat, and I have access to the controls, then I can log the time as a "safety" pilot.