Ash Cloud, How Dangerous is it?

[TheAnimus]

First lets admire the staggering power of nature, if ever you need a reminder quite how insignificant we are look at this:
http://www.bbc.co.uk/news/uk-scotland-13519331

It is only a little volcano you know. But it is quite beautiful.

So what hazards do these things pose to planes?

Props, basically not much at all. A piston engine in a plane is almost the same as a car, the carburetter filter could get clogged, which would mean you'd have a bad time, but an experienced pilot would see this coming with strangely lean amounts of mixture (air + fuel) been required. Flying in desert at low altitude is more likely to create an issue.

So no one has ever suggested suspending GA flights in the ash clouds, in fact even in Iceland people are flying them to see the volcano.

So ignoring turbo props because no one gives a damn, on to the Jet engine.

Jets require quite a lot more air to fuel thanks to been a jet engine, but planes have gone through the ash clouds before and survived:
http://en.wikipedia.org/wiki/British_Airways_Flight_9
Now in this case its worth noting commercial jets shouldn't be flying through ash clouds. They shouldn't be flying through thunderstorms either (see Air France and unlike the ash cloud, those poor people have quite possible died at the hands of dangerous pilotage).

The thing is not all ash is the same, and no one really knows how dangerous it is so its all air on the side of caution. But after a little while googling I've been un-able to find something that even begins to state tolerance levels for an engine.

So lets try and keep this thread FUD free, and see what decent sources people have been able to find for why we should shut down scotlands airspace!

[TheAnimus]

http://www.metoffice.gov.uk/volcano/public/rgb.html

Now this is the forecast from the Meto, thing to look for a local EU flight is a 0<FL200 area. As you can see based on where it has already been and where people are closing its not really that serious at the min. But what will all the decision makers do.....

[roachcoach]

Jets require quite a lot more air to fuel thanks to been a jet engine, but planes have gone through the ash clouds before and survived:
http://en.wikipedia.org/wiki/British_Airways_Flight_9

Survived...with all 4 engines failing.

Is that a gamble worth taking, really?


I'm one of the greatest opponents of the "but what if" crowd - life is dangerous, live it and shut up or get the hell out of the way. However, in this case I'm prepared to make an exception - that plane was lucky it had the altitude and velocity to glide out, had it not, it was a really, really big lawn dart. I still wear seatbelts in my car

Engine failure from the ash is documented, I wouldn't rely on "luck" to sail through.

I have nothing but sympathy for the decision makers, because no matter their call - people will moan relentlessly and armchair experts will tell them how wrong they were.



I think the real question, the one that should be asked is this: In the aftermath of the last eruption, why did the tests stop when the ash went away? They were doing test flights to check the engines over last time near the conclusion but that all seems to have stopped. Did we have reason to think this would never happen again? Morons.


Edit: Re air france, there's every chance the guy was just taking a dump, co-pilots can fly

Sorry, copilots are expected to be able to fly.

[TheAnimus]

As I said below, its well documented that they shouldn't fly straight through them.....

The question is what level is OK, no manufacturers are willing to publish guidelines on this!

[roachcoach]

As I said below, its well documented that they shouldn't fly straight through them.....

The question is what level is OK, no manufacturers are willing to publish guidelines on this!

Isn't part of the issue though that they're dry so invisible to aircraft radar so they are pretty limited in their detection ability?



I think there's a plethora of reasons for that but it'll boil down to "it depends" and companies won't risk it on "it depends".

[Stringent]

All it takes is one flight to crash because they flew in 'guideline' amounts of ash and there will be uproar. Safest thing is to close the airways, and make ready the boats/ferries/channel tunnel.

[TheAnimus]

Yes, but its not invisible to certain measurement devices, my understanding is they know a lot about the cloud and its composition, the big problem is prediction for more than 12 hours, knowing when it will stop.

The link in my second post shows quite how well we can forecast it too. So whilst it might not be quite as simple as normal operations, we can at least avoid it, keep closer than usual eye on the engines as there are obvious warning signs of the ash build up being serve if your looking for it.

You can also see how based on the forecast they decided to shut down Edinburgh!

[TheAnimus]

All it takes is one flight to crash because they flew in 'guideline' amounts of ash and there will be uproar. Safest thing is to close the airways, and make ready the boats/ferries/channel tunnel.

But people die from flying all the time.... And we know that people in the past have survived flying straight through it, so why not just have a simple rolling exclusion zone?

[roachcoach]

But people die from flying all the time.... And we know that people in the past have survived flying straight through it, so why not just have a simple rolling exclusion zone?

As Stringent says - if they get it wrong...people will scream blue murder.

[Kata]

So no one has ever suggested suspending GA flights in the ash clouds, in fact even in Iceland people are flying them to see the volcano.

Last time, large parts of the UK, Belgium, the Netherlands and elsewhere banned ALL aviation; including gliders and hot air balloons. Why? Because of the risk of "engine failure". Thankfully someone who did not have **** for brains was finally located in government, and they relaxed the restrictions a little.

[jim]

If you ask Eric Moody, very dangerous.

If you ask Michael O'Leary, not dangerous at all.

So, who am I going to trust? Hmm...

Seriously, I know that the ash isn't a guaranteed plane killer, but why are so many people so anti-caution. A heck of a lot of planes have gone down in the past because of an "it'll do" attitude to safety, where people bend the rules just a little bit because it doesn't seem too dangerous.

Personally, I'd rather they took the precautions and kept the lives. Yes, there are limits. We could get a refitted plane for every flight, but we've got to have boundaries for economic reasons. At the other end, those boundaries are also there for safety reasons. When people starting bending those boundaries, accidents happen.

[Kata]

Boundaries should be prepared on the basis of the available evidence. All the evidence in this situation says "we can fly".

As you know, the Eric Moody event was entirely different to what we are now experiencing; we're talking flying through alleged "ash clouds" that leave no detectable trace on the aircraft, not a concentrated volcanic plume. Comparing the Eric Moody flight to the current ash clouds is like using a thunderstorm as evidence for why you think people should carry an umbrella when the humidity is high. "People get really wet in thunderstorms, we can't be too careful!"

[jim]

Boundaries should be prepared on the basis of the available evidence. All the evidence in this situation says "we can fly".

As you know, the Eric Moody event was entirely different to what we are now experiencing; we're talking flying through alleged "ash clouds" that leave no detectable trace on the aircraft, not a concentrated volcanic plume. Comparing the Eric Moody flight to the current ash clouds is like using a thunderstorm as evidence for why you think people should carry an umbrella when the humidity is high. "People get really wet in thunderstorms, we can't be too careful!"

That's what I'm saying, it's all about boundaries. I know the Eric Moody case is a worst case scenario, but at the same time we can't just say "let's let the airlines decide", because we know for a fact that safety isn't always the primary concern.

If the boundaries are wrong, then fair enough, it needs to be re-evaluated. But what I can't bear is this constant attack on it, as if we're just so stupidly *safety mad*, and okay so it's a bit dangerous but not that dangerous.

There's a big difference between saying okay, the limit is being re-evaluated and is now anything over 2mm ash at 30% concentration (numbers made up), and saying okay, the limit is probably a bit overly cautious so we'll just forget about it and fly anyway. I fully believe that the airlines would happily do so and hope for the best.

[Kata]

You do realise that the airlines have a vested interest in not crashing too, don't you? Perhaps the gung-ho attitudes you assign them would be valid for some of the more dodgy African carriers, but any airline like that is banned from flying in Europe in the first place. A major incident such as a crash is devastating to an airline, they don't want it any more than we do.

The problem I have is with the idiotic knee jerk political responses, such as banning glider flights in case of engine failure; I mean *seriously*?? Other countries outside of Northern Europe have been dealing with volcanoes since the dawn of aviation; but the European attitude is that anything that isn't invented in Europe is invalid, and obviously inadequate. It's an attitude that is visible in almost all aspects of European aviation regulation, and the industry suffers greatly from it.

[jim]

You do realise that the airlines have a vested interest in not crashing too, don't you? Perhaps the gung-ho attitudes you assign them would be valid for some of the more dodgy African carriers, but any airline like that is banned from flying in Europe in the first place. A major incident such as a crash is devastating to an airline, they don't want it any more than we do.

Like Alaska Airlines Flight 261? No, I don't trust the airlines, even the more reputable ones.

The problem I have is with the idiotic knee jerk political responses, such as banning glider flights in case of engine failure; I mean *seriously*?? Other countries outside of Northern Europe have been dealing with volcanoes since the dawn of aviation; but the European attitude is that anything that isn't invented in Europe is invalid, and obviously inadequate. It's an attitude that is visible in almost all aspects of European aviation regulation, and the industry suffers greatly from it.

Yeah I agree that in cases it can be a bit daft, and obviously there's no reason why a glider should be banned. As I said, there needs to be a balance of some kind.

[Kata]

You'll note that the maintenance changes imposed by Alaska Airlines were done with the full approval of the FAA. The very regulators who you say we should be trusting to keep the airlines in check?