What are the public factors considered in establishing forum non conveniens?

Hypo 1: Bob, a resident of California, owns an airplane manufacturing facility in California. He ships airplanes around the world. One day, one of Bob's airplanes is involved in a crash in Scotland involving Scottish citizens. The survivors and victims of the crash bring a suit against Bob in a California federal court. Result: Bob would likely be successful in invoking forum non conveniens because it doesn't make sense to hear the case in a California federal court even though jurisdiction is proper. Bob would argue that this case involves Scottish citizens, flying in Scottish airplanes, who experienced a crash within Scottish territory. The evidence of the crash is in Scotland, as is the evidence of whatever may have caused the crash. Further, the witnesses are in Scotland, as are the victims and their families. It would be super inefficient to try to hold the trial in California when everything about the case is in Scotland. Moreover, Scotland has an interest in pursuing justice for their citizens, and so it is unfair to deprive their court system of an opportunity to hear the case. On the flip side (and you will often have to argue the other side), the Scottish victims may want to have the case heard in a California federal court because there is an opportunity to have higher damages awarded. Thus, the court will hear these arguments and, in the end, likely grant forum non conveniens, which means that the case is dismissed but the parties are free to pursue it in another court with jurisdiction, like in Scotland. Note: the reason that the court can't transfer the case to Scotland is because Scotland and California are completely different court systems with no ability to transfer a case between them. There's no link between the two systems to move one case from another, so it must be brought again by the plaintiffs, starting over from scratch.