Comment by walkabout
9 hours ago
> In 1975( 50 years ago when the tooling you cite was built), nobody would want to fly in 20 year or 10 year old aircraft, today we don't care how old the air-frame we fly are.
Given the DC-3 is still(!) in service, and there were surely a ton more of them flying in 1975 than today, I'm not sure that's true. And that's far from the only example of a more-than-10-years-old-in-1975 aircraft that was certainly still in wide use in 1975.
Any big shift around then was probably because of the development of high-bypass turbofan jet engines. Not so much driven by "old airframes seem risky" as "pre-high-bypass jet engines are enough more-expensive to operate that airlines will abandon them rapidly". Those engines went into wide use in the 1970s (developed in the '60s). We (demonstrably) had "reliable, long-lived airframe" figured out by the '30s, with some refinement through the '40s but nothing that rendered those '30s models necessarily obsolete (see again: the DC-3, a 1936 design). More-efficient subsonic jet engines were what caused turn-over in a certain segment of the market in the '70s, not so much "I won't trust an old airframe".
DC-3 was an exception[0]
The point was not on any specific technical or economic factor. It was to illustrate that rapid evolution in comfort, or speed and also safety[1] means people will prefer adoption of newer tech quickly and not be concerned about longevity and actively devalue slightly older products.
When the improvements start becoming marginal only then longevity start to matter. The planes developed from 90s to now have lot to offer operators but not much new[2] to passengers, we are still designing(not just operating) new 737 variants after all. Most people cannot tell the age of the plane if the cabin has been refreshed.
This preference for newer generation of tools has little to do with previous generations having different values as nostalgically some like to ascribe to, but simply to technology maturity was my point.
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[0] As impressive the 100 year history and the longevity of a pre-war design has been. We have to keep in mind the dynamics of unpressurized plane operating at less than 300 knots with a service ceiling of less than 25,000 feet is hardly comparable to that of any modern passenger aircraft cruising at 0.90+ mach for 12-15+ hours daily at 37,000 feet going through tens of thousands pressurization cycles.
[1] Airframes perhaps were not a popular safety concern directly, pressurized and reduced noise in cabins were major selling points.
Air safety regulations were famously said to be written in blood. It is undeniable that was massive drop in fatalities in 80-90s from 60-70s after safety became concern and everyone held both operators and manufacturers accountable.
[2] Improved range or better engine reliability that meant we can do longer ETOS on twin engine etc do benefit passengers indirectly.