I'm glad to have experienced flying in the retro futuristic 747 but the Lufthansa A340-600 felt like a proper top of the line spaceship. I still can't fathom that twin engine is now deemed safe for long haul flights. I always feel uneasy when crossing the Atlantic with one.
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> feel uneasy when crossing the Atlantic with one
Modern engines are ridiculously reliable and ridiculously powerful. That means they don’t fail frequently. And when they do, one is enough to limp to safety [1].
[1] https://simpleflying.com/united-airlines-boeing-757-engine-l...
Yes, I know all of that and we do have the empirical data to support the safety argument. Still there's just too much efficiency mindset at play for my taste. I prefer big buffers, especially in mission critical scenarios.
But then you still probably choose to drive your car every day, despite that doing so is many, many times more risky than flying over the ocean in a twinjet.
Human preferences ultimately shape these marketplaces, but humans are fundamentally terrible at evaluating risk, especially for extremely negative but highly unlikely outcomes (see also: terrorist attacks, home invasions, etc).
Personally I minimize time spent in automobiles, whether driving or as a passenger, precisely because it’s so dangerous. My risk of sudden death is drastically lower on days that I don’t spend any time inside a vehicle moving at high speeds on the highway.
Yeah no question, I definitely also feel uneasy on the road. Contexts differ greatly by the way.
> prefer big buffers
If the second one fails, you still have at least 75 miles [1]. (More engines would have actually hurt in that situation.)
How much of a typical transatlantic route (say, London -> New York) is within 75 miles of a safe landing zone? I assume routes are chosen to optimize for this, to some degree.
> How much of a typical transatlantic route (say, London -> New York) is within 75 miles of a safe landing zone
ETOPS 180 means 180 minutes from a diversion airport. At 737 speeds that could be 1,300 miles.
I don’t think two modern engines have ever failed in a way that wouldn’t have taken out four, e.g. the Air Transat flight, where again, having more dead engines’ weight and drag would have reduced glide distance.
Both the A350 and 777 can technically take off with only one engine.
4-holers can cross the Atlantic with an engine out and barely notice. See this Emirates A380 that flew from New York and had to shutdown an engine over Newfoundland. OK it didn't fly all the way to Dubai it had to divert. To Kuwait!
https://www.businesstraveller.com/forums/topic/ek-a380-flies...
Not exactly according to the rules but still.
So called “accelerate-go” versus “accelerate-stop”. It is conditional, and not limited to these two models. They need to accelerate to a specific airspeed based on loading, temperature, and usable runway length. Prior to that airspeed, engine failure means abort. At and after reaching that speed, takeoff continues.
Right, there is no circumstance where they would want to. I'm just talking about the power of a single engine on one of those birds.
The safety calculus isn't quite as simple as "more engines = safer". Having more engines also increases the chances of one of the engines failing, and engine failure can be quite immediately dangerous to the aircraft if it's uncontained. (You don't want to get hit by a detached fan blade.)
Even if contained it can be dangerous.
Light twin piston airplanes, likwise double the odds of engine failure, but due to the dramatic loss of excess thrust, the good engine actually becomes the problem, e.g. Vmc limitation.
The assymetric thrust force can exceed control surface force needed for controlled flight. The solution is never go below Vmc airspeed, but if you do it requires immediate power reduction. And that has consequences that often inhibits committing to the proper action prior to loss of control. In most cases power reduction commits the pilot to landing sooner than preferred, and in a likely suboptimal location.
> You don't want to get hit by a detached fan blade.
For the morbidly curious, this occurred on Delta Flight 1288:
https://admiralcloudberg.medium.com/written-in-metal-the-sto...
Good point.
> I still can't fathom that twin engine is now deemed safe for long haul flights. I always feel uneasy when crossing the Atlantic with one.
If one engine fails, you have another. If the second fails, you glide.
Since 1953, there have been less than 50 airline flights that have required gliding:
* https://en.wikipedia.org/wiki/List_of_airline_flights_that_r...
Per the usual trope-y statistic: if you want a safe trip for your vacation, don't drive to the airport (which would be the riskiest leg of the journey).
Crossing the Atlantic generally isn't a problem, most routes take you close to land. It's crossing the Pacific, like from US to Hawaii, that is a bit cagey.
Why? Any modern twin-engine plane can operate just fine on a single engine. Dual engine failure is extremely rare, especially at altitude - most of the time it's birds like the USA1549 at much lower altitudes.
> Any modern twin-engine plane can operate just fine on a single engine
Introducing Boeing’s latest innovation… ESOPS!
I thought their latest innovation was the sunroof…
They invented that back in '88 when the roof came off Aloha Flight 243! (https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243)
Yeah, I know all of that plus the ecological / economic side.. it still irks me. Maybe I've seen just too many failing redundant disk arrays in my career.
You should work on that. Generalizing tech/CS concepts to the physical world is a common shortcoming I see among SWE's. They just don't understand concepts of variability in the real world or experimental physical science.
Fortunately aircraft are evaluated on a much stricter standard than hard disks...
You don't say! ;P