Out of the FAA regs:
Although I couldn't find the definition of "solo flight" under
§ 61.1 Definitions and Abbreviations (as if it isn't clear enough
), but we do all agree that one need to do 10 hours of solo flight under § 61.109 right? The examiner will check if the applicant logged those ours in his logbook and at least here is where it's getting interesting...
How can somebody have a different interpretation of "sole occupant of the aircraft"?:
§ 61.51 Pilot logbooks.
[...]
(c) Logging of pilot time. The pilot time described in this section may be used to:
(1) Apply for a certificate or rating issued under this part or a privilege authorized under this part; or
(2) Satisfy the recent flight experience requirements of this part.
(d) Logging of solo flight time. Except for a student pilot performing the duties of pilot in command of an airship requiring more than one pilot flight crewmember, a pilot may log as solo flight time only that flight time when the pilot is the sole occupant of the aircraft.