Boe 747 obselete in 20 yrs.
Well it depends on your criteria. It was probably obselete as it made its first flight. But the first commercial flights of the Boe.707 were in 1958/59,certainly the Pan-Am tansatlantic service was 1959 and there are many 70's and it's contemporarythe Douglas Commercial 8 series,a better machine,in commercial service today.
First B.747 flight was 9 Feb 1969 and commercial service soon after. It's going to be around a lot longer than its antecedants, so define obselete but do'nt confuse it with usefulness.
Those Tilt/Squat switches are going to be around for a long time.
Rgds to Renton.