Originally Posted by
XcalibeR
To answer your last question first, yes, it's against the rules, if they logged it as solo. Solo, as was answered before, is all the time where the pilot was the only person onboard the aircraft. So they could log the initial part of the flight as solo, but then the part with passengers as only PIC. Which, for a commercial, is just as good as solo (With the exception of the flight for 61.129(a)(4))
Also as was said before, it's really only used for student pilots. With that in mind, though, FAA Form 8710 (Application for an airman certificate) has spaces for "solo", "cross country solo" with separate columns for PIC time. So even if you have your private, you would need to figure out your total solo times if you ever apply for another certificate or rating. It really sucks, especially if the PIC and Solo columns in your logbook are the same (this I know from experience. grrrrr...)
Ummm...maybe I am not understanding what you wrote but I have done much training since my PPL to include ATP and 4 types. I've never logged any solo beyond my student pilot time and it's never been a problem. This includes my F-16 time which is solo 99.69% of the time.
Bottom line, don't log solo after your PPL unless your training towards Gliders or Rotary Wing aircraft. Nobody cares if you are by yourself once you are rated.