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I think you are missing the point here, or at least misapplying it. These are minimum figures, but if the four-engined airliners used in transoceanic flights we
by mannykannot 6y ago
I think you are missing the point here, or at least misapplying it. These are minimum figures, but if the four-engined airliners used in transoceanic flights were actually built to have no more reserve power (above the minimum necessary to keep flying) than the 133% you are quoting, they would have always have been less safe from engine failure than contemporary twin-engined airliners (which, in practice, always achieved the 200% reserve), as they, just like the twin-engined aircraft, could not have tolerated any more than a single engine failure - but then, ETOPS would either not have been necessary, or should also have been applied to four-engined airliners. ETOPS is primarily about the risk of two engines failing (and secondarily about range with one engine out.)
- nickff 6y agoMaybe the people at the FAA in the 1950s who wrote the so-called 60-minute rule missed your point, but I don't know what to tell you.
- mannykannot 6y agoThe 60-minute rule does not explain or justify your 133% claim with respect to four-engined aircraft - in fact, it is evidence against it: in practice, four-engined airliners, unlike twins, could tolerate more than a single engine failure.
- nickff 6y agoI just looked at a few airliners, and the 2-engine aircraft all had significantly higher power to weight ratios than the 4-engine aircraft.
- mannykannot 6y agoThat does not justify your 133% figure, nor the explanation you gave for it. That explanation implied that four-engined airliners could only tolerate the loss of a single engine.