The ashtrays are there, even today, because it is suspected that this flight [0] went down when someone disposed a cigarette butt in the lavatory trash, causing a fire.

A reminder that aviation regulations are written in blood.

[0] https://en.wikipedia.org/wiki/Varig_Flight_820

> A reminder that aviation regulations are written in blood.

It's enormously expensive for an airframe manufacturer to deal with the fallout of a crash.

There aren't any engineers in an airframe manufacturer willing to sign off on a faulty design. Some good engineers are so worried about that they get shifted to working on conceptual projects.

I took a loooong time for Boeing to convince the FAA that a twin engine jet was safer than a 4 engine for ocean crossings.

> took a loooong time for Boeing to convince the FAA that a twin engine jet was safer than a 4 engine for ocean crossings

I don't believe they convinced the FAA twin is safer, just that it meets the necessary safety margins. Airlines want them to meet that regulation for fuel efficiency, but I'd want a source that they're actually safe-er, instead of simply safe enough

Boeing proved it safer. The reason is the increased complexity of more engines increased the risk of a major problem.

My source is I was told this by the engineers who where involved.

Not necessarily safer but safe enough. A modern 4 engine jet should still be safer than the 2 engine equivalent

tldr for the wikipedia article:

this plane did not crash, it made an emergency landing 2 miles from the airport in an onion field. Only 10 crew and 1 passenger survived. The other 123 souls aboard died of smoke/CO inhalation from the fire.

the sole surviving passenger, 21-year-old Ricardo Trajano, disobeyed the instructions to remain in his seat.