The Journal of the American Society of Anesthesiologists recently published an article on "Management of In-flight Medical Emergencies. The article is quite good and discusses what should be expected both from the provider and by the provider from the airline. Here is the link.

I've provided medical assistance on planes before and I don't think it is unreasonable for the crew to see some proof that I have the qualifications that I say I have nor does the author of the article. I carry my wallet card which my state licensing authority requires me to carry so providing identification is not a problem for me. The "I stayed at a holiday inn express" syndrome is unfortunately common and I believe most emt's or paramedics have seen some form of it at one time or another on scene and probably so have many airlines and airline crews.