From memory docjames related a story where he was flying on a business class award redemption and spent most of the flight in economy attending to a patient. I don't think he was compensated and the least QF could have done in this situation would have been to refund his QFF points.
Without re-hashing the whole story, essentially that's correct. However I was disappointed not to receive any formal thank-you from Qantas - a letter would have sufficed. Note I did not want "payment". I did feel a bit stiff though - I should have redeemed a YASA instead of a JASA! I will also add the crew were generous (two bottles of wine). It was more the lack of acknowledment from QF management - the crew I couldnt fault and they were most thankful. A simple letter or email would have done it (even a form letter).
The issue of "payment" is vexed as there become medico-legal liabilities, whereas to my understanding, provided you act reasonably, you are covered by the good samaritan act, as well as most medicolegal insurers (again, provided you act "reasonably"). As
drmikki points out, Most doctors will gladly assist unless they feel way out of their depth, and in many cases, the (older) clinical knowledge a radiologist or psychiatrist may posess, is still better than a lay-person.
The definition of reasonable could well be open to interpretation.
FWIW I seem to have quite a regular "strike-rate" of being on a/c where a doctor is "requested". My understanding is they cannot force you to assist either - you may be incapacitated and unable to assist (read: too much J class wine list!), or indeed, a PhD in a non-medical field. My MIL travels as Dr when her PhD is in history of immigration. In the case
JohnK mentions, they clearly knew (per manifest) I was the only Dr on the flight, but they had to wait for me to "enquire" whether there was a problem, and ask whether I could help. I managed that just a few seconds before they made a PA announcement.