I think that a "Good Samaritan" law for Doc's on Airplanes was enacted recently. (Sorry doc, had to respond being a Lawyer and all.)
Last year I was on a DL 727 that filled with smoke while getting into position on the runway in BOS. We sat there while the plane's AC cleared the smoke caused by it overheating. We then took off! No engineers came and checked the plane, nothing. You would now have to launch my finacee from a cannon to get her into a DL plane.
In 83' the Icelandic DC-8 I was on applied full power and started to roll down the runway, when we got halfway they slammed on the brakes and turned around. The pilot then informed us that #3 engine did not have sufficient oil pressure and we were going to try it again. Not a great thing when flying to Iceland, that North Atlantic ain't warm.
BSL