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> 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

> 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 6y ago
> 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 6y ago
  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 https://www.youtube.com/watch?v=HSxSgbNQi-g
  - snowwrestler 6y ago
    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.
    - redis_mlc 6y ago
      Your comments are both superficial and unhelpful. > they have determined it is safe enough. This is a common misconception. Regulators believe ETOPS is safe enough based on engine reliability before an actual flight loses an engine. Then it's an emergency. The probability of the engine failure goes from almost 0.0 to 1.0. See the difference? > It’s really weird to imply that losing one engine is a ditch situation. I didn't say that was a certainty, but it is more likely to be a ditching situation for several reasons. The lower a jet flies, the more fuel it consumes. If there's also a pressurization problem, descending to 10,000 feet would rapidly burn fuel. Also, operating a jet engine at maximum power increases the likelihood of failure, and by itself is more risky. > Modern airliners can take off on one engine. You cannot plan a passenger flight for takeoff on one engine for safety reasons. Not all airplanes will successfully be able to clear obstacles on one engine. The only time it's allowed to takeoff on one engine with passengers is after V1. > “It’s a 4-engine ocean” is indeed an old expression. It's still true. ETOPS is for cost-minimization, not safety. It's always safer with 4 engines than 2. IOW, you don't know anything about the topic, like virtually all HN readers. Just because the risk of ETOPS has been normalized, it doesn't mean that it's as safe as 4 engines.
  - freehunter 6y ago
    >Actually several have diverted I’m not a pilot but isn’t that a good thing? Diverting a flight as opposed to... crashing?
    - throwaway0a5e 6y ago
      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 6y ago
        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 6y ago
        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).
  - justsid 6y ago
    > 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.
    - redis_mlc 6y ago
      > This is a super misleading technical truth. Nope, read on. > There usually is an engine out altitude where it’s most efficient to fly on a single engine. If there's an engine failure and a related pressurization problem, the plane will descend to 10,000' and burn excessive fuel, possibly overheating. There are often such problems after an uncontained engine failure. > this is all based on statistics. ETOPS is based on statistics before an actual flight has an engine failure. Then those stats mean nothing after an actual engine failure and you have an emergency. See the difference? Why haven't we lost an ETOPS airliner yet? Lucky so far, but it will happen. And then everybody will be like, "How is that possible?"
  - nemetroid 6y ago
    > 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.

mjg59 6y ago

> 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 6y ago
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 https://www.youtube.com/watch?v=HSxSgbNQi-g
- snowwrestler 6y ago
  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.
  - redis_mlc 6y ago
    Your comments are both superficial and unhelpful. > they have determined it is safe enough. This is a common misconception. Regulators believe ETOPS is safe enough based on engine reliability before an actual flight loses an engine. Then it's an emergency. The probability of the engine failure goes from almost 0.0 to 1.0. See the difference? > It’s really weird to imply that losing one engine is a ditch situation. I didn't say that was a certainty, but it is more likely to be a ditching situation for several reasons. The lower a jet flies, the more fuel it consumes. If there's also a pressurization problem, descending to 10,000 feet would rapidly burn fuel. Also, operating a jet engine at maximum power increases the likelihood of failure, and by itself is more risky. > Modern airliners can take off on one engine. You cannot plan a passenger flight for takeoff on one engine for safety reasons. Not all airplanes will successfully be able to clear obstacles on one engine. The only time it's allowed to takeoff on one engine with passengers is after V1. > “It’s a 4-engine ocean” is indeed an old expression. It's still true. ETOPS is for cost-minimization, not safety. It's always safer with 4 engines than 2. IOW, you don't know anything about the topic, like virtually all HN readers. Just because the risk of ETOPS has been normalized, it doesn't mean that it's as safe as 4 engines.
- freehunter 6y ago
  >Actually several have diverted I’m not a pilot but isn’t that a good thing? Diverting a flight as opposed to... crashing?
  - throwaway0a5e 6y ago
    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 6y ago
      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 6y ago
        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).
- justsid 6y ago
  > 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.
  - redis_mlc 6y ago
    > This is a super misleading technical truth. Nope, read on. > There usually is an engine out altitude where it’s most efficient to fly on a single engine. If there's an engine failure and a related pressurization problem, the plane will descend to 10,000' and burn excessive fuel, possibly overheating. There are often such problems after an uncontained engine failure. > this is all based on statistics. ETOPS is based on statistics before an actual flight has an engine failure. Then those stats mean nothing after an actual engine failure and you have an emergency. See the difference? Why haven't we lost an ETOPS airliner yet? Lucky so far, but it will happen. And then everybody will be like, "How is that possible?"
- nemetroid 6y ago
  > 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.