My grandpa is a doctor and he was told several years ago not to show that he is a doctor in the case of an emergenc especially on flights to/from the U.S. because if he can't help cause in case of missing equipment, medicine or even if there's no chance to save the patient's life, somebody will always try to get some money out of it and go to court...

He always said that he will do in any case but I don't know whether LH "insures" the doctor whether he can't help or he's doing a fault...