Thanks Penko!
Sorry FD, I seem to have hit a nerve!
No offence to FEs intended nor (I think) implied. It just shows how one can be misunderstood. I was always taught that if someone misunderstands you, the fault probably lies with the way you phrased what you were trying to say. So, to adhere to that principle, let me apologise for my clumsy wording and try to sum up my point again:
It is possible to fly just about any aircraft as a single pilot, given enough time to prepare. That doesn't mean it should be encouraged. What does it 'prove'? Nothing much, except that with no abnormalities or time pressures to deal with, the task of getting an aircraft airborne and back on the ground again is not beyond most professional flight crew (pilots and F/Es). I must say I enjoyed the challenge of finding out what some unfamiliar knobs and switches were for. I'm sure the simple piloting required under such low stress conditions would also not be beyond some 12-year-old boys. I've seen some sim engineers hand-fly Cat 11 approaches and landings to a much higher standard than most pilots could. Does that make me feel inadequate or threatened as a professional pilot? Not in the least.
By complete contrast, the safe and orderly operation for hire and reward requires the co-ordinated input and actions of a minimum number of trained and qualified aircrew. That number is determined by the certifying authority and in the case of the 'classic' wide-bodies and other types, certainly and deservedly includes the Flight Engineer. It's obvious that the minimum crew must be able to deal with the worst conceivable combination of failures, environmental problems, etc. The system design and displays of the older jets are too complex to be managed by a two-pilot crew under such conditions. The extra pair of eyes are also useful in normal operations. I could go on but I suspect that you agree with all of these points.
I did try to separate the notion of simply 'flying' against that of 'operating', and I certainly don't consider myself any sort of 'higher being'! In all my flying, I have always learned from my students (mostly about my own shortcomings as an instructor) but also about all sorts of things that they had a better handle on than I did. I count this exchange as one of those learning opportunities.
So, to answer the original post again: Yes, it think it's possible for a 2 man crew to operate a 747 Classic, DC-10, 727 or Tristar if none were ex-FEs themselves. But I don't think I would like to be a fare-paying passenger on such a flight!