[justsid]

> It's unlikely that an airliner can maintain altitude on one engine, so the risk is high that once a problem occurs, things can go bad fast. Ditching 300 passengers in the open ocean guarantees fatalities.

This is a super misleading technical truth. There usually is an engine out altitude where it’s most efficient to fly on a single engine. Just like there is an altitude where it’s most efficient with both engines operating. The two don’t need to be the same.

Planes don’t automatically become ETOPS certified, every plane gets tested.

The first step is to certify the type of aircraft itself, for which it is flown on a single engine for the required time of the ETOPS rating. So ETOPS-180 means 180 minutes of flying with a single engine. Not in a simulator, with a real aircraft.

The second step is that each operator also has to become ETOPS certified. You can’t just buy an ETOPS certified jet and fly it over the atlantic. There are additional requirements for crews and mechanical staff, including more regular checks of the aircrafts.

Lastly, this is all based on statistics. So operators have to publish statistics about their fleet. If say engine outs are increasing for a specific airframe and/or operator, it’s possible that their ETOPS rating goes down or is completely suspended.