[redis_mlc]

> Wow, I would have never guessed that!

Airliners are merely business tools - operators have no romance for any plane.

If a 777 is even 2% more efficient than a 747, the 747 is grounded and chopped up.

The related factors are that 4 engines is more maintenance than 2 engines, the classic 747 is no longer certified for passenger use in the USA (wiring and fuel-tank inerting ADs), and ETOPS allows twin-engine flight on almost all commercially-viable oceanic routes. (ETOPS makes me nervous af.)

Source: commercially-rated airplane pilot.

[mjg59]

> ETOPS makes me nervous af

The only case I can think of where an ETOPS flight had both engines fail due to something other than fuel exhaustion was BA38, and it's hard to say a quad jet would have managed better there. I can understand the gut feeling that the safety factor has been reduced, but given several decades without horror stories is it really still something to be nervous about?

[redis_mlc]

FYI: Actually several have diverted. You should study the ETOPS requirements to see how nervous the regulators are. Each ETOPS flight has special requirements for alternates that have lodging, food and reasonably nearby (timewise) maintenance. (Cold Bay is not a fun place to be stranded.)

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.

I understand that non-pilots think "it's handled", but that's not really the case.

That's why the old expression "it's a 4-engine ocean" came about.

"Small Planes Over Big Oceans (ETOPS Explained)"

https://www.youtube.com/watch?v=HSxSgbNQi-g

[snowwrestler]

What does it mean to say that regulators are “nervous” about ETOPS? Regulators are always nervous; that is their job. If they permit something it is because they have determined it is safe enough.

It’s really weird to imply that losing one engine is a ditch situation. Modern airliners can take off on one engine. ETOPS 330 certifies them for operation on one engine for 5.5 hours continuously. They may have to descend a bit from max altitude but there’s a big difference between that and ditching.

More flights have experienced fatal crashes due to pilots flying a perfectly functional airplane into the terrain, than from both engines failing. On objective evidence, you should be more worried about the pilots than the engines.

“It’s a 4-engine ocean” is indeed an old expression.

[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.

[nemetroid]

> 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.

There's nothing likely or unlikely about it - for an aircraft operating an ETOPS flight, the performance characteristics with one engine operative are well known, and taken into consideration when doing the mandatory diversion planning.

[freehunter]

>Actually several have diverted

I’m not a pilot but isn’t that a good thing? Diverting a flight as opposed to... crashing?

[throwaway0a5e]

You know how in a bureaucracy heavy industrial workplace even the most distant of "near misses" gets the book thrown at it even if it doesn't make sense.

Well flying is like that kind of workplace but cranked to 11.

[freehunter]

Right, but if an engine is going to fail... it’s going to fail. Whether it’s over land or over sea, it’s going to fail. I haven’t heard of anything saying jet engines are more likely to fail over the open ocean. So that plane would be diverted anyway, even if the failure happened over land. The only difference in risk is how far the plane has to go to find a runway they can land on, which still can be a problem over land because it’s hard to safely set a 747 down in the middle of the Congo or the Amazon or Siberia or northern Canada, etc. And even the biggest 787 can land on a shorter runway than even the smallest 747.

Again I’m not a pilot but it seems like diverted planes isn’t the problem, the problem is finding a safe place to set the plane down if a failure does happen. Yes the ocean makes that difficult, but so does a lot of land.

[nemetroid]

Land can actually make it trickier in some aspects. If your aircraft experiences depressurization, a rapid descent to a breathable altitude is required (how rapid depends on the aircraft). In mountainous areas this can be difficult (but is, of course, planned for).