There is certainly nothing critical running Solaris on a 747 or any other airplane. All airborne software needs to get certified by FAA and is developed and evaluated through the lens of the DO-178B standard.
> I was contracted to test the systems on a Boeing 747. They had added a new video system that ran over IP. They segregated this from the control systems using layer 2 - VLANs. We managed to break the VLANs and access other systems and with source routing could access the Engine management systems.
Perhaps there's nothing critical running Solaris, but apparently the critical systems are accessible from the systems running Solaris.
I guess we will never know for sure.