I know it doesn’t make that much sense, but I asked my professor and he said it depends on the airplanes. P-3 Orion does this to save fuel during missions IRL, but then he mentions Boeing 747 he said that it would be too heavy and forced to descend thus slow down even more by shutting down engines. His conclusion is that if it would save fuel, it would be the SOP. About SE takeoffs that I demonstrated, it’s just because I am in a F-14, if it’s A380 it’s takeoff roll is 3KM with all engines so they need it all turned on. Basically the plane needs to be able to fly at the same thrust setting and not lose too much altitude for this to happen, that’s what he told me.
Is there actually a question here? If so, I am guessing it is why do aircraft use multiple engines when it could conceivably be more efficient to use fewer. The answer would be as follows:
- Modern aircraft have been optimized (within basic SOPs) in their design to be most efficient in their designed format - i.e. all engines functioning as expected with the tolerances required for regulatory approval (e.g. 1 engine out after V1)
- Civilian aviation, especially commercial aviation, is as one would expect a highly regulated industry. It would be hard to explain to the general public, as would be required with free press, why an aircraft shut down an engine during flight. This is even more problematic given the general concern that an engine shut off during flight may not be able to restart if needed.
In summary it is unlikely there are massive savings to be unlocked by shutting down engines, and even if there were it would be unlikely they would outweigh the costs of educating the general public.
Yes. Cause one player told me this is not a thing IRL and I wanna make it clear, but yes for airliners it should fly with all of its engines.
But, if you lose an engine, or have to shut it down for certain reasons, isn’t necessarily always an emergency. Depends on circumstances and phase of flight. Also comes down to specific operator’s SOP as to whether diversion or RTB is a must or not.
I’d love to see an operator’s SOP that says if you have a lost of engine in flight it’s not an emergency.
It’s not an engine loss, it’s shut down on purpose. There are more types of planes than cars, so the difference of operations are expected.
Well then… Guess this wins this point lol
The several multi engine operations I have flown, we don’t shut an engine down in flight if we lose an engine in flight we’re landing immediately. As the old saying go - If you lose one, the other one will fly you to the crash site.
I agree on engine loss situations, but you also have auto-rotation as your last line of defense right?
Yes, if we lose both engines we will if need be.
If you have 4 engines, and one (as in ONE, not more) goes out (not on fire, obviously, but out) or has to be shutdown due to simple mechanical reasons/not running in limits, you can continue on per some SOP’s.
Whose SOP allows that?
Fuel conservation misconceptions imposed by ‘bean counters’ is way off track. Shutting down engines to save fuel only makes the remaining ‘on line’ engines work that much harder and they guzzle fuel to keep up with the work load. Sadly I witness this stupidity daily in my job by having to ‘isolate’ (not pulling their weight, but idle) railroad locomotives in the consist. End result is wasted fuel and added wear and tear on the running units. Bottom line…this bunk is swallowed hook line and sinker by company executives because of some accountant’s (who knows nothing of physics, or the industry) column on a expenditures spreadsheet. $$$$$$ on the short term is all they see.
Probably several on 74’s and 340s… I remember a British Airways flight back in the day, early 2000s maybe that flew all the way to England on 3 engines after they had to shut one down right after takeoff. Pretty sure it happened recently with Lufthansa, though Im not privy to their SOP, just know they were adamant that it wasnt an emergency. Cathay has had it happen before too if I remember correctly.
Hm okay… I haven’t heard of US operations doing this I need ask my friends who fly the 747 see what they say about their company’s SOPs. Our fixed wing operations doesn’t allow this and a company I work with closely in the summer flying four engine operations doesn’t either.
I know for a fact Boeing certifies 74 to fly on 3. Goes without saying. And while no one would ever take off with an inop, if it happens in flight, not necessarily an emergency. Every operator has different SOP’s though. Southwest considers an aircraft inop even if coffee pot isnt working. Easily fixed, of course, but aircraft inop.
Sure it maybe able in flight, now is it smart that’s not my decision since I don’t fly the 747. It sounds very in fuel efficient…
That’s true, like our is completely different then let’s say Alaska Airlines or Delta…
I’ve heard of other companies doing this also… A regional company I fly with has the same thing.
Found that Lufthansa one from recently. https://youtu.be/EvVfLZO9CT4
And found the BA one from way back when.
Sure, before 2007 the FAA said the aircraft was unworthy and also tried to fine them for it, which also changed.
Now in the US I do not believe that companies will allow this to happen, since it’s the Feds and they will probably hammer down on you. Now what the Europeans do is a completely different ball park.
Indeed on the efficiency. I think the BA flight in the wiki article above proves that point. They ended up having to land short of destination. I wasn’t aware of that before. haha. Wonder if the emergency declaration at that phase in flight was simply fuel related.
BA definitely doesn’t allow this anymore. I have had to wait an hour because they couldn’t fly with the first class curtain having fallen off, and only an engineer was allowed to fix it.