Some comments about the DH
Comet airliner on this thread are really out of line.
The Comet was an extremely fine airliner. The Comet I had its problem which resulted in two very bad, fatal crashes. Sadly the Comet was not alone (DC-10 baggage doors). And we are talking about an era when also the all new Lockheed Electras fell apart in the air.
The later Comets, especially the various Comet 4 versions, gave sterling service for many years. Not so much in America as in the rest of the world.
The military Comet, the Nimrod, is currently being upgraded to Mk 4 version with new center wing box, new engines and a lot more. It is likely that the last Nimrod variant may still fly a hundred years after the first Comet went to the air. That will be a few decades after the last B707 variant (KC-/EC-135, E-3, E-6, E-8 and such) has been converted into beer cans.
By that time the last Comet successor, the VC
-10, will also be long time gone.
What other airliner design can you imagine in year 2049 to have given 100 years of service? There will of course still be DC-3s around, but only flying for the fun of it.