Sole pilot or sole-manipulator of the controls? I've seen some interesting interpretations of "solo" vs "PIC" in the US where UK PPL's hour building for the purpose of achieving 100 hours PIC prior to a modular CPL course are in fact 'dual' with an FAA CFI sitting with them also logging PIC apparently for insurance purposes. Which leads to a question of certification: I see that the Stearman is 'N' registered and in the AAIB report of the contact with the R44, the Commander is recorded as holding a PPL; I take it this is referring to TCT and if so, I presume she holds at least an FAA Private Pilot Certificate to operate as PIC of an 'N' registered aircraft (In particular the flying conducted in the US most recently)? An Airman Inquiry through the FAA reveals nothing.