So most of these three-engine jets are now freighters.
Three-engined jetliners sort-of-made-sense back in the day, back when turbofan engines were less reliable and less powerful. But these days, in the era of the Big Twin, the only use for trijets is as a freighter.
As here, near the tall, tall Rincon 1 building in SoMa, a UPS Airlines freighter coming in to SFO from an unusual direction on account of the crazy wind we’ve been having:
Click to expand
Fundamentally, the MD-11 is an evolution of the ill-starred McDonnell-Douglas DC-10, which became a very unappealing aircraft back in the 1970’s. The revamped MD-11 is indeed more appealing to operators, and that’s why you can still see them above.
But, as they say, mistakes were made. The tailplane was decreased in size for improved fuel economy however the MD11 became trickier to handle as a result.
And twinjets will always beat any fuel efficiency race with trijets.