Airline accidents can be very difficult to manage, since often there are multiple parties involved from multiple different jurisdictions and locations. If you purchased your ticket from a US airline, there is a chance that the US airline who sold you the ticket will be responsible for the airline accident. However, you may also be able to hold the airline that was flying the plane responsible, depending on the situation.
Various pieces of legislation have been passed that attempt to regulate airline accidents and aviation litigation, including rules under the Warsaw Convention which establish jurisdiction for airline and airplane accidents. However, these rules may not apply in every case (the Warsaw Convention generally applies only for international flights, for example). Further, your particular case may have other factors that affect where litigation may be brought.
In general, however, there is precedent to indicate that a US airline can be held responsible for an accident, even if the plane that actually crashed belonged to a foreign airline. The precedent occurred when a Swissair plane crashed in Halifax, Nova Scotia on September 2, 1998. In that particular case, Delta Airlines was considered responsible for two dozen passengers because it had sold them tickets. Under the law, this relationship between Swissair and Delta was known as "code-sharing."
If you find yourself dealing with a situation where you are not certain who should be held legally responsible for a plane crash, it is in your best interests to contact an aviation attorney. Because such cases often involve so many different parties, class action litigation groups will form that you may choose to join. A lawyer can give you information about these class actions or can assist you in filing your own lawsuit against the proper airline who is likely to be held liable in a court of law.