And, 2 engines are actually more reliable than 4 - less that can go wrong.

No.

Let *p* be the probability of one engine failing during a typical flight. We can assume *p* is a very small number, because the engines are designed and maintained well.

The probability of both engines failing on a 2-engine aircraft is *p*^2, an even smaller number. The probability of all 4 engines failing on a 4-engine aircraft is *p*^4, a number that is even smaller still than *p*^2. So, having 4 engines instead of 2 reduces the probability of all engines failing, and makes the plane more reliable.