Or "the plane is certified such that the remaining engine has enough power to take you to the crash site". Indeed.
As outlined above, you double the probability that a mechanical problem occurs. (For p small, 1-(1-p)^2 is around 2p).
Now, if the pilots are very much on top of things (well trained and current), then they can control things and safely land at the nearest suitable airport. However, if they make a mistake (and that's surprisingly easy [1]), it could easily be fatal.
A single-engine plane with an engine failure, in contrast, becomes a bad glider, with a decent chance of surviving the ensuing forced landing.
[1] For example, the TransAsia ATR 72 twin turbo prop clipping a bridge in Taiwan after the crew erroneously shut down the "good" engine.
Just want to point out that "shutting down the 'good' engine" isn't some isolated incident - that was a contributing factor to the British Midland Flight 92 crash [0] as well.
As outlined above, you double the probability that a mechanical problem occurs. (For p small, 1-(1-p)^2 is around 2p).
Now, if the pilots are very much on top of things (well trained and current), then they can control things and safely land at the nearest suitable airport. However, if they make a mistake (and that's surprisingly easy [1]), it could easily be fatal.
A single-engine plane with an engine failure, in contrast, becomes a bad glider, with a decent chance of surviving the ensuing forced landing.
[1] For example, the TransAsia ATR 72 twin turbo prop clipping a bridge in Taiwan after the crew erroneously shut down the "good" engine.
https://en.wikipedia.org/wiki/TransAsia_Airways_Flight_235
https://www.youtube.com/watch?v=RSoZOsIC25M