Most aircraft have a plethora of unannunciated events for which there's a QRH, and a host of others that simply need to be addressed based on airmanship and common sense. Loss of engine oil, for example, may not have a procedure, but may state that given various factors, it may be an indication, or may be an actual oil loss, or it might represent something else (failure of fuel-oil heat exchanger, for example). The procedure may tell us to use judgement and watch for other indications. On a blue-water oceanic trip involving limited diversion possibility with long transit times between destination and departure, and ETP alternates (which, let's face it, legally only need 15 minutes of fuel on arrival...not a lot of room to screw around), a diversion is complicated b the use of things like operations specifications that further reduce fuel (B043, B044), etc, and ETP alternates that may raise the workload substantially. Judgement time; more heads with more experience on site, in real time, are better than fewer, dumb automation, and a dispatcher eating crackers in a dim, stale room that wreaks of last week's coffee.
Loss of all aircraft nav (standby nav, IRS reference unavail)...I've experienced that twice now, once mid pacific, once mid atlantic, two different aircraft types, two different operators, and something that really needed to be handled on site, rather than from afar. Until that's sorted out or otherwise handled, needle, ball and airspeed time; basic airmanship, and remote control won't do it. Much better to have extra heads.
On my captain observation ride in one type, we developed a fuel situation that had two checkairman, two captains, and two first officers on the flight deck trying to sort out, which started with the strong possibility of loss of one engine due to fuel starvation (fuel migrating, valve stuck), then a second engine, and finally, the very real possibility of a third due to an escalating problem. It began 45 minutes out of Honolulu. I was a lot happier having extra hands on deck. And on site, rather than somewhere else.
Arrival into LAX, began configuring, and the airplane began turning. Asymmetric problem, roll problem. Busy area, additional hands welcome, good crew coordination, and oh-so-important that at least one person is flying the airplane and dedicated to that, while the other handles radios, checklists, and everything else.
I could go on all day with examples, and each one could be picked apart all day, but it doesn't matter...most of us will have them, and the bottom line is that while an employer might salivate at the thought of saving the overhead cost of a first officer on a long flight, safety is invaluable, and that's what's being bought with a second pilot.
Descending in the mountains in Afghanistan, the cockpit went dark. Pitch black. Nighttime. Big hills. The flight engineer restored power quickly, albeit with a split bus, and I made the call to hold the procedure there, rather than troubleshoot and try to restore more. We had nav, and we could look at the problem once we got on the ground. Which we did. Thank God for FE's. That was in an airplane designed for three, and which took three...but I've flown airplanes that were designed for three, rebranded for two, and really required two. The notion of taking it down to one pilot and flying a large transport category airplane in the system as if one were flying the King Air somewhere to get a five hundred dollar hamburger, is ludicrous. It's well and good to suggest that on an eventless oceanic trip one need only make an occasional HF call, position report, or CPDLC checkin, but we don't just fly in such conditions. We also fly into the busiest corridors on the planet, like the Northeast, or the NAT. Couple such places with things that go wrong, and the workload goes up considerably...quite possibly beyond what one pilot can, or should handle, and certainly can or should, safely.
I've tried my hand at a lot of things in aviation, including some fairly demanding stuff, from formation flying under powerlines to low visibility formation through narrow burning canyons in severe turbulence with exploding trees, and frankly, the most demanding, highest workload flying there is, involves single pilot IFR. I certainly thought so a great many years ago, and my view on that hasn't changed, but is more firmly cemented than ever, based on a lot of years of experience doing an extremely broad range of things in this business. The mentality that "if we can send a rocket to the moon, why can't we do single or no-pilot IFR in big airplanes" reminds me of a poster a girlfriend used to have on her wall; "if we can send a man to the moon, why can't we send them all?" Cute, but pointless and nonsensical. After trillions of dollars, NASA has managed a few remarkable feats, but given so few flights, a remarkable number of dire emergencies, including shuttle losses. We'd all be hurting for jobs if such a high loss rate occurred in commercial aviation. That Artemis mission that just splashed down, that was one, with mannequins board, and I'm not ready to take a bite of an apple that tastes of one-successful-experiment-in-space-means-we-can-abandon-flight-crew.
If one is to suggest that a transoceanic crew has too little to do, therefore we should cut the crew in half and up the workload on what's left, I'm thinking the person making such a suggestion is either management, has never set foot in a cockpit, or needs his or her head examined. There is far too much that is unpredictable in an airplane that requires on-site handling, and though it may occur infrequently, it still happens, and once is enough. Moreover, workload can be high under normal circumstances; add abnormal circumstances, and it can be too high. Our job is safety; we preach it, worship it, adhere to it. Compromising it by reducing to one pilot (or no pilots) flies in the face of a call to safety. It really does.