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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

#481

Post by DocTomoe »

jacquesm wrote: post #470
kqr wrote: post #453

Earlier quoted context omitted.

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.

Seconded.

That being said: I have - for some years now - started to read air accident board reports (depending on your locale, they may be named slightly different). They make for a fascinating read, and they have made me approach debugging and postmortems in a more structured, more holistic way. They should be freely available on your transportation safety board websites (NTSB in America, BFU in Germany, ...)

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

#482

Post by jstummbillig »

gsnedders wrote: post #67
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?

As others have said, final fuel reserves are typically at least half an hour, and you shouldn't really be cutting into them. What if their first approach into MAN had led to another go around? With a major storm heading north-easterly across the UK, the planning should have reasonably foreseen that an airport 56 miles east may also be unavailable, and should've further diverted prior to that point. They likely used t…

Interesting. To me it does not really make sense to think in terms of fuel left because, no matter the reserves, there can always be a situation so unlikely, so outside the ordinary, that it will drain all fuel reserves before you make it to the planned destination.

I have no clue how else to think about it though.

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

#483

Post by MaxikCZ »

jacquesm wrote: post #418
dotancohen wrote: post #364

Earlier quoted context omitted.

> fuel burned stays burned, you don't 'get it back' The it that they get back is not fuel, it's energy. Maintaining flight is energy management. They are getting the gravitational potential energy back, which is converted to velocity on descent, or bled off in drag by slowly losing altitude while maintaining airspeed.

So it seems. But because you want to land you then want to shed all that velocity. So you 'get it back' only to have to waste the bigger fraction of it. A go around is much like a mini take-off, you just miss the runway portion of it.

Nah. You want to land, but you are really not shedding most of your velocity until after touchdown. What you gain by burning fuel is energy, and you can either bank it into altitude, or velocity. You must shed both to land, but not so for go-around. There you shed almost all of your altitude, but you keep most of your velocity -> you still have a lot of energy left. That's why on go-around you spool your engines and start climbing basically right away, unlike typical takeoff, where after spooling up the engines you are still earth-bound until you build enough velocity.

So you only ever really lost your "altitude" component of energy, not "velocity" one. You run your engines at TOGA (Take Off / Go Around = maximum thrust), thrust to gain mainly altitude, only increasing speed a little bit. Then on another approach attempt you use both the altitude and excess velocity bank again.

In flight, ~all your energy losses go to drag. Doesn't matter if you bank it into speed or altitude, both is exchanged to be at minimums (0 altitude above ground, lowest safe landing speed) at touchdown. If you produce extra energy in your engines, it has to go to either speed or altitude, which you then pull out again, usually by maintaining speed while lowering altitude while having engines at idle.

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

#484

Post by kqr »

jacquesm wrote: post #470
kqr wrote: post #453

Earlier quoted context omitted.

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.

I want to write more about this, but it has been a really difficult subject to structure. I gave up halfway through this article, for example, and never published it – I didn't even get around to editing it, so it's mostly bad stream of consciousness stuff: https://entropicthoughts.com/root-cause-analysis-youre-doing...

I intend to come back to it some day, but I do not think that day is today.

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

#485

Post by faku812 »

abtinf wrote: post #40
jacquesm wrote: post #23

That is very exceptional. I've written fuel estimation software for airliners (cargo, fortunately), and the number of rules regarding go-arounds, alternates and holding time resulted in there usually being quite a bit of fuel in the tanks on landing, by design. I've never heard of '6 minutes left' in practice where it wasn't a massive issue and the investigation into how this could have happened will make for interes…

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?

[dead]

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

#486

Post by kqr »

AnthonyMouse wrote: post #475
kqr wrote: post #453

Earlier quoted context omitted.

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…

> Trying to prevent accidents while not paying attention to hazardous states amounts to relying on the environment always being on our side, and is bound to fail eventually. The reason they had less than 30 minutes of fuel was because the environment wasn't on their side. They started out with a normal amount of reserve and then things went quite badly and the reserve was sufficient but only just. The question then i…

This is why staying out of hazardous conditions is a dynamic control problem, rather than a simple equation or plan you can set up ahead of time.

There are multiple controllers interacting with the system (the FADEC computer in the engines, the flight management computer in the plane, pilots, ground crew, dispatchers, air traffic controllers, the people at EASA drafting regulations, etc.), trying to keep it outside of hazardous conditions. They do so by observing the state the system and the environment is in ("feedback"), running simulations of how it will evolve in the future ("mental models"), and making adjustments to the system ("control inputs") to keep it outside of hazardous conditions.

Whenever the system enters a hazardous condition, there was something that made these controllers insufficient. Either someone had inadequate feedback, or inadequate mental models, or the control inputs were inoperational or insufficient. Or sometimes an entire controller that ought to have been there was missing!

In this case it seems like the hazard could have been avoided any number of ways: ground the plane, add more fuel, divert sooner, be more conservative about weather on alternates, etc. Which control input is appropriate and how to ensure it is enacted in the future is up to the real investigators with access to all data necessary.

-----

You are correct that we will not ever be able to set up a system where all controllers are able to always keep it out of hazardous states perfectly. If that was a thing we would never have any accident ever – we would only have intentional losses that are calculated to be worth their revenue in additional efficiency.

But by adopting the right framework for thinking about this ("how do active controllers dynamically keep the system out of hazards?") we can do a pretty good job of preventing most such problems. The good news is that predicting hazardous states is much easier than predicting accidents, so we can actually do a lot of this design up-front without first having an accident happen and then learning from it.

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

#487

Post by nabla9 »

abtinf wrote: post #40
jacquesm wrote: post #23

That is very exceptional. I've written fuel estimation software for airliners (cargo, fortunately), and the number of rules regarding go-arounds, alternates and holding time resulted in there usually being quite a bit of fuel in the tanks on landing, by design. I've never heard of '6 minutes left' in practice where it wasn't a massive issue and the investigation into how this could have happened will make for interes…

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?

>One pilot who reviewed the log said: “Just imagine that whenever you land with less than 2T (2,000kg) of fuel left you start paying close attention to the situation. Less than 1.5T you are sweating. But this is as close to a fatal accident as possible.”

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

#488

Post by nomilk »

gregsadetsky wrote: post #349
greggsy wrote: post #320

Earlier quoted context omitted.

Sub required. I can wait for the Pete the Irish Pilot’s take though.

this one is available - https://www.flightaware.com/live/flight/RYR3418/history/2025...

Is there a way to hear the pilots / ground conversing?

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

#489

Post by trapexit »

grapesodaaaaa wrote: post #425
Schiendelman wrote: post #281

Earlier quoted context omitted.

Want to bake your noodle? Because the market responds to your behavior by slightly lowering the cost of flying to fill those seats, demand increases to match from slightly lower income people. Because they then organize their lives slightly more around cheap flights, it gets even harder to lower the impact of flying. Paradoxically, rich people like us (you're a tech worker too...) flying more, because we're less sens…

Clearly you have thought a lot about carbon reduction, so I have a question for you. Is a plug in hybrid or EV less polluting if you don’t have rooftop solar? edit: I think I know the general answer, but I’m splitting hairs comparing a replacement car for an ICE vehicle that I have.

You don't need your own rooftop solar. You can time your charges for when power is cheap (i.e. renewables are highly represented in the grid mix). In many locations you can get an electricity tariff that changes by time of day, either fixed times of day or nearly real-time to track the current wholesale price.

Here in Scotland, we have an EV electricity tariff that give us low rates between 00:30 - 05:30 while the wind turbines spin and demand is low, and our plug-in hybrid is programmed to charge during those hours. (We also run the dishwasher, washing machine, and tumble dryer on time delay during those hours as much as possible)

With nearly all of our car trips being local, the ~25 mile electric range the plug-in hybrid is rarely exceeded. We fill the petrol tank maybe once every 3 or 4 months, or when we're on a road trip.

Pure EVs are harder to justify in the UK currently unless you do basically all of your charging at home, because with 20% VAT added to the price of electricity from public chargers, and too-low fuel taxes, the per-mile cost is similar to—or sometimes more expensive than—driving on petrol. It's shockingly bad public policy.

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

#490

Post by lwhi »

jstummbillig wrote: post #482
gsnedders wrote: post #67

Earlier quoted context omitted.

As others have said, final fuel reserves are typically at least half an hour, and you shouldn't really be cutting into them. What if their first approach into MAN had led to another go around? With a major storm heading north-easterly across the UK, the planning should have reasonably foreseen that an airport 56 miles east may also be unavailable, and should've further diverted prior to that point. They likely used t…

Interesting. To me it does not really make sense to think in terms of fuel left because, no matter the reserves, there can always be a situation so unlikely, so outside the ordinary, that it will drain all fuel reserves before you make it to the planned destination. I have no clue how else to think about it though.

So maybe the thing we can improve is an understanding of likelihood?

I.e. prevent the journey from occurring if weather conditions are likely to be adverse above a certain threshold?

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