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Ryanair flight landed at Manchester airport with six minutes of fuel left

theguardian.com

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Re: Ryanair flight landed at Manchester airport with six minutes of fuel left

#461

Post by drstrangecharm »

alterom wrote: post #437
TZubiri wrote: post #414

Earlier quoted context omitted.

My guess is higher air density means more wind resistance, which acts as negative forward acceleration.

Not just that. Jet engines are efficient at higher speeds because the exhaust of the jet engine is fast . If the plane is going fast as well, that exhaust is more or less stationary relative to the ground. The engine works to exchange the position of the plane with the position of the air in front of it. If the plane is going slow, it's accelerating the air backwards . That's where the work is going, making the engin…

You are right that accelerating the air backwards more reduces efficiency but I think it should be mentioned that the jet engine has to accelerate the air backwards to do any work pushing the plane forward. Picking it up and setting it back down affects the air with a net force of zero and therefore the force pushing the plane forward is also zero.

Re: Ryanair flight landed at Manchester airport with six minutes of fuel left

#462

Post by auxiliarymoose »

in_cahoots wrote: post #442
jacquesm wrote: post #140

Earlier quoted context omitted.

As I wrote elsewhere in this thread I actually wrote software to estimate the amount of fuel a jet should load to comply with the rules. This was commissioned by the airline and they were scared shitless that they would ever be found to be in breach of the regulations on this aspect. It is one of those red lines that you really do not wish to cross. There are other aspects of flight where you are right but this parti…

As an aviation fan just reading this thread is quite eye-opening in terms of how much risk tolerance the average commenter has vs what is standard in the aviation community and on aviation forums. It's almost like peeking into two different worlds. I wonder if there would be any value in teaching an "engineering when lives are on the line" or "war stories from accident investigations" classes to new engineers. I feel…

Yeah it bothers me to no end with the "engineering"-inflation of various jobs.

Like, I'm definitively not an engineer, nor does my day job really involve engineering, yet my title contains Engineer! I'm a proud CRUD monkey and designer.

I have done engineering work previously when developing hardware, and it's really a different mindset (even in an agile & fast-moving engineering org). Safety, cost, reliability, multidisciplinary integration, etc. just don't really come up in a lot in web and app development (which is a wonderful thing, really—I love it!)

Re: Ryanair flight landed at Manchester airport with six minutes of fuel left

#463

Post by whycome »

throwup238 wrote: post #236
whycome wrote: post #210

Earlier quoted context omitted.

[flagged]

That’s about as useful as opening a fortune cookie and reading it off as an answer. Straight from the horse’s mouth: https://web.archive.org/web/20230630013840/http://www.boeing... In the first table they list 2307-2374 kg of fuel for takeoff and climb.

You’re talking to the wrong horse though.

Isn’t a 737-8 the max 8 variant? It uses newer dual CFM LEAP-1B engines. How does it compare? I can’t really find the data. The spec you’re referring to is for the older 737-800.

Another fortune cookie:

https://www.aircraft-commerce.com/wp-content/uploads/aircraf...

It suggests an overall savings of ~14% over the 737-800 but doesn’t look at specific takeoff/climb comparison.

I wasn’t posting the LLM output as a source of truth. I was just using it to question the uncited value. And I still really don’t know the answer. If you’ve got another data source I’d love to get it.

Re: Ryanair flight landed at Manchester airport with six minutes of fuel left

#464

Post by mierz00 »

ant6n wrote: post #300
Aeolun wrote: post #270

Earlier quoted context omitted.

I don’t think that’s so much? A car burns 1 liter to travel 15 kilometer’ish, and carries 4 people. An airplane burns 40 liters to travel 15 kilometers too (900 kph), but carries 160 people. That’s about 40x more than the car, so the fuel economy per passenger is about the same. Of course jet fuel is probably a bit more polluting, but it’s still interesting how close it is.

The greenhouse effects of flying is about 3-5x the effect of just burning the fuel.

Could you explain why this is?

Re: Ryanair flight landed at Manchester airport with six minutes of fuel left

#465

Post by jama211 »

kqr wrote: post #453
abtinf wrote: post #40

Earlier quoted context omitted.

Naively as an outsider, this situation seems like everything worked as intended? On a nominally 2h45m flight, they spent an extra 2 hours in the air, presumably doing doing fuel intensive altitude changing maneuvers, and were eventually able to land safely with their reserves almost exhausted. I’m a little confused by what there is to investigate at all. How much fuel should they have landed with?

In safety-critical systems, we distinguish between accidents (actual loss, e.g. lives, equipment, etc.) and hazardous states . The equation is hazardous state + environmental conditions = accident Since we can only control the system, and not its environment, we focus on preventing hazardous states, rather than accidents. If we can keep the system out of all hazardous states, we also avoid accidents. (Trying to preve…

Well said, will think about asking this attitude towards my child, seems very helpful

Re: Ryanair flight landed at Manchester airport with six minutes of fuel left

#466

Post by jama211 »

alterom wrote: post #437
TZubiri wrote: post #414

Earlier quoted context omitted.

My guess is higher air density means more wind resistance, which acts as negative forward acceleration.

Not just that. Jet engines are efficient at higher speeds because the exhaust of the jet engine is fast . If the plane is going fast as well, that exhaust is more or less stationary relative to the ground. The engine works to exchange the position of the plane with the position of the air in front of it. If the plane is going slow, it's accelerating the air backwards . That's where the work is going, making the engin…

Variable pitch turbine fans sound very interesting! Perhaps in the future as tech improves and fuel efficiency incentives continue to increase.

Re: Ryanair flight landed at Manchester airport with six minutes of fuel left

#467

Post by vdqtp3 »

kqr wrote: post #436
howard941 wrote: post #347

Earlier quoted context omitted.

The glider guys would always suggest a forward slip. It's a lot of fun to do. It's not taught often enough during primary training for powered airplanes.

Aren't low-speed slips something that makes planes flip upside-down when not used very carefully? (Inadvertent rudder changes corrected with opposite aileron resulting in a snap roll.)

A cross controlled stall can result in a spin (which is probably what you mean by flip upside down). The rudder changes aren't inadvertent, they're intentionally opposite the aileron input - the goal is essentially to fly somewhat sideways, so the fuselage induces drag.

In general forward slips are safe, but yes you have to make sure you keep the nose down/speed up. There's little in aviation that isn't dangerous if you aren't careful.

Re: Ryanair flight landed at Manchester airport with six minutes of fuel left

#468

Post by vdqtp3 »

hshdhdhehd wrote: post #371
henryfjordan wrote: post #293

Earlier quoted context omitted.

We shouldn't aim for 0 crashes due to low fuel though. How many deaths does carrying around 3x fuel than what you reasonably need contribute to via extra pollution? We should aim for 1 every 10-100 years or something reasonable like that.

We dont aim for 0. Zero means dont fly. one in every 100 years globally for all flights would be very safe.

On the contrary - commercial aviation does aim for perfection.

Re: Ryanair flight landed at Manchester airport with six minutes of fuel left

#470

Post by jacquesm »

kqr wrote: post #453
abtinf wrote: post #40

Earlier quoted context omitted.

Naively as an outsider, this situation seems like everything worked as intended? On a nominally 2h45m flight, they spent an extra 2 hours in the air, presumably doing doing fuel intensive altitude changing maneuvers, and were eventually able to land safely with their reserves almost exhausted. I’m a little confused by what there is to investigate at all. How much fuel should they have landed with?

In safety-critical systems, we distinguish between accidents (actual loss, e.g. lives, equipment, etc.) and hazardous states . The equation is hazardous state + environmental conditions = accident Since we can only control the system, and not its environment, we focus on preventing hazardous states, rather than accidents. If we can keep the system out of all hazardous states, we also avoid accidents. (Trying to preve…

If you haven't done so: please write a book. Aim it towards software professionals in non-regulated industries. I promise to buy 50 to give to all of my software developing colleagues.

As for 'N', for turboprops it is 45, for jets it is 30.

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