Hawker Siddeley HS-121 Trident

The Trident was the first airliner in the world to make a fully automatic landing in commercial service, and a commercial failure: BEA had it shrunk to suit its own routes just as the market wanted something bigger, and the Boeing 727 — the same shape, a size up — outsold it fifteen to one. No type certificate for it is reachable — the FAA's regulatory system is closed to us and EASA never held the type — so this entry carries its history but none of the certified weights the rest of the library is built on.