Originally Posted by
pandaperth
At LHR if you are transiting to destination outside of the U.K. and the airlines concerned have an inter-line agreement, then your bags would normally be checked through to the final destination - i.e no customs inspection at LHR (unlike what happens in the US of A)
You can check bags though the US on ITI connections at some airports and not collect them. For AA, MIA and DFW come to mind. You still clear Customs and Immigration, but your checked luggage does not.