JF

You're so correct. The key word though, is 'could'.

We need to know if it 'will' cause the damage, or not.

At least this period of flying in low concentrations of ash will likely provide an answer.


Granted, with a little forethought, the answer to the 'how much is too much' question could easily (if at a cost) have been discovered.

We will now find out.

The cost to the airlines of the enforced stoppage must exceed by many times what the 'research', which was too dear to do, would have cost.

plus ca change.:rolleyes:


We make money (BA forecast £600m loss this year) or we fold.

Possibly - but only after a long delay!

As I understand CAA and EASA directives, and current airlines reaction to them, the initial basis of ALL investigation of potential ash encounters starts with EITHER in-flight observation of ash in the air or hitting the aircraft (St Elmo's Fire, ...?) OR the strong possibility that the route DID pass through an ash cloud. Then, specific ground inspection will be done, starting with Mark 1 Eyeball examination of the aircraft for 'traces of ash'.

As has already been discussed much earlier in this thread, there's a stack of good evidence that a flight CAN pass through quite dense ash with NO in-flight indication AT ALL and nothing found visually post-flight (in particular, the NASA DC-8 incident in 2000).

Seems to me that the key problem that remains completely unaddressed is any 'backstop' testing so that even in the absence of any other evidence, ash in turbine hot section cooling systems WILL be detected and appropriate maintenance done, ideally before major damage occurs. (Don't know whether any ash removal from inside blades is even theoretically possible without tearing the whole engine apart!) Filters on bleeds from the engines provide a DEFINITE indicator of ash ingestion but as far as I know there is no organised plan to test them post-flight.

Remember that a lot of aircraft tend to fly reciprocal routes (A to B, then B to A, maybe several times in the same day). Ash encountered on multiple flights will obviously become a CUMULATIVE problem, especially if low levels of ash are unexpectedly present on a busy route and not detected by any of the current means!

Everyone is wondering what happens when you fly through a widely dispersed ash cloud and its after effects.

Here is link to the USGS study on exactly that - the aftermath of Mt. Pinatubo in 1991 (bigger eruption than this one)Casadevall

Flying for CX at the time I remember Manila was closed for 2 weeks while the eruption was on and the ash scraped off the RWYs afterwards (55nm downwind from the Volcano).

Other than that there were various re-routes on HKG-AUS vv and in the (very busy) South China Sea.

There was some damage to aeroplanes but mostly very minor (see above report). One IFSD was reported in the 18 encounters during the aftermath.

To all the doom forecasters:

Have any of you actually been up there this last week? Are any of you actually airline pilots?
If so: have you refused to fly this week?

I have been to the UK, to various parts of Scandinavia and to Italy this week. All the AMT`s that I have spoken to have told me that they haven`t seen any evidence of ash on any of the aircaft this week.

Let`s just all be grateful for the experience our industry is gaining these days on the subject.

Off to fly now....

I'm not 'forecasting doom'!
Just the potential for massively-increased engine maintenance costs, which will inevitably and eventually hit YOU straight in the pay-cheque!

What difference does it make make whether you've flown through ash, flown in an EPZ or even just 'flown'?

I thought it was generally agreed that in many situations, even CAVOK, it was possible, even likely that flight-deck crew will see NOTHING on instruments or outside the aircraft that will give any clue AT ALL of the presence of ash! If you've got an instrument that images diffuse ash-clouds, you're sitting ona gold-mine!

Is it not a better idea to spend a relatively small amount of money on post-flight detection of an ash encounter than to risk millions on engine overhauls and spares that may not even be do-able on a reasonable timescale? (eg. repairs to all 4 engines on the NASA DC-8 after 8 MINUTES flying through ash at night: $3.2million)

PS
It's interesting that there WERE symposia and publications (eg. by USGS) after Pinatubo in the early 90s but not much got done about it! Much easier to justify activity and expenditure after a major event that cost LOTS of money. Much harder after the dust has settled :) Well - here we are again!

It is generally stated, although it does not appear to be true. It is clear that if the crew can not see out (eg. it is moonless night over ocean or they are in IMC) they can't see ash. However, in all of the documented encounters it was clear after the fact that the ash was visible (Eg. the stars become obscured but the crew couldn't tell if they were in or under cloud because it was night - the NASA DC-8).

To JFs point - the above applies to the immediate flight safety incidents that have been documented by USGC or ICAO. It is quite possible (even probable) that flying in invisible ash could significantly reduce the life of engine components and cause premature failure - I don't think anyone in this thread is arguing otherwise. However, that appears to be much more of an operational economic and maintenance inspection question than a flight safety issue.


There conclusion appears to have been don't carry on in an ash cloud - (determined by the cabin fills with haze, you smell sulphur, St Elmo's fire appears, your windshield gets sand blasted). Also, there appeared no evidence of any long term ill effects of operating in the general environment. How much more study should they have done?

Err - no. The (now very old) USGS report on Pinatubo includes several notes about aircraft damage found well AFTER flights that could have caused it! The authors commented that the reason that there's no location given for some of the tabulated incidents is that no-one knew where they happened!

And I was not suggesting more studies - there already seems to have been plenty of evidence, even from the early 90s. I meant real-world policies and procedures that actually MEASURED stuff (like ash in the air and collected on / in aircraft when there was likely to be a problem) and then ACTIONS to minimise risk and further cost. Ad hoc Mk 1 Eyeballing ain't it!

This really is the bit that gets my goat. I and most others I listen to or read are not claiming by any stretch of the imagination that an aircraft will fly tomorrow, suffer multiple engine failures and glide for a landing into Blackpool. We are not forecasting doom at all. In fact I am very aware of the possibility and indeed hoping for it to turn out to be the case that nothing comes of this at all. But the single point is WE DO NOT KNOW WHAT WILL HAPPEN.

How pathetic an answer is it to say "we'll find out what damage is done in due course". Or for someone to say they flew 6 flights over the last three days and did not have single problem - as if this gives any indication of general conditions to be expected across the whole European network. That's the same ridiculous logic that was used to open the airspace so quickly in the first place.

Damage can be done and in fact, damage has been done. I completely agree that there must be conditions under which it is safe to fly and it is extremely unlikely that sustained significant damage would be done to every aircraft on every route. But we have not had any proper examination of that possibilty whatsoever. Worse than that, some of the test flights which did occur did find potentially damage causing levels of ash. Although it seems this finding was too close to the agrrement on the regulations. The point of no return must have been reached. Most signifcantly though in my mind they found multiple varying layers of ash conecntrations when this new regulation is based an three zones of constant and evenly spread concentration - something that nature will never provide.

This isn't about simply whether an aircraft will fly and crash. This about so much more than that. It is about the heavily commercially orientated mindset of those tasked with being objective and non-commercially orientated.

If this was a scenario that was likely to continue for weeks or months then I would understand the need to find a way to save our entire industry. But our industry as a whole was never at risk because this was NEVER going to last that long. Our safety process has been influenced by shareholders. Plain and simple. That's my problem.

No proper system of analysis nor operational procedures have been employed. Let me ask all you airline guys out there that challenge those who did or didn't fly already since the clampdown: When you're up there, after having studied your ash charts before you left and you're pootling through swedish airspace and suddenly ATC advises you of a new VA sigmet for the area you are flying in or intending to land in what do you do? The same as the rest of us - tear it up and throw it away because the chart didn't show it in your area I imagine. How do you deal with a pirep? That's something completely different surely? And there has been pireps of ash encounters - whether they were valid or not is another question - but aircraft are ignoring them completely. We have been led by the bloody nose here!!!!

Can anyone explain how the AACC shows zone 1 and 2 limited to Iceland while Gothenburg is confirmed to be zone 2 by ATC?

Put your head back there so I can a good hold on your nostrils while I walk into this cave to see what's in it.............

mm_flynn

how can you say

but feel that it wouldn't be a flight safety issue?

That's just strange! So if an engine quits 20 hours before it planned overhaul that's a problem for the bean counters more than for us?

The logic for ash being such a signficant safety issue is that it is one of those common mode failure things. If you are in sufficient ash to fail one engine, the odds are pretty high that the rest of them are going to roll back in a few moments. I think everyone agrees that is a big problem.

However,

engine overhauls are not scheduled 1 hour before expected failure, they have quite a lot of safety margin and typically have some type of condition monitoring to detect accellerated wear. A failure due to Ash wear is likely to be at a random time, and therefore the redundancy logic works.

Just to be clear - I am not saying flying in invisible ash has no effect - just that the risks seem similar or lower to lots of other risk.

The figure is failure within 100-500hours after the encounter, according to NASA. So in a few weeks you could have thousands of wrecked engines and billions of dollars in repair bills, plus possibly years get replacement parts.

That would concern more than just the bean counters, wouldn't it?

Why are we wasting all this money over ETOPS procedures, IFSD rates, etc, when it is clear that most here are prepared to accept a higher level of risk. Have we ever lost an aircraft due to strictly ETOPS issues? Based on that the procedures are superfluous.

I think we should be looking at what we may have to do if (when?) Katla erupts as many claim is a highly likely event.
Eyjafjallajökull might just be the warm-up!
We dont have much time to think this thing out.

mm_flynn I understand your redundancy logic theory. Nice one! Never really cnosidered that. Although as you say, each engine is likely to be affected in a similar way and to a similar degree. So is it not cutting the redundancy logic a little fine? Can it not be considered possible that another engine may suffer similarly within a short period of time following an ash encounter?

Normal redundancy works because failures are much more random and occur from tiny differences in quality of manufacturing or unusual isolated interaction with other components and therefore the time scale for failure is very wide and varying.

But if what peter says is true then if you are likely to see problems within 100-500 hours then that is much too small a window to expect isolated and seperate issues. What I mean is that if one engine dies 105 hours after an ash encounter, there has been reasonably significant damage. It is therefore correct to assume another engine will suffer the same fate within a very short period.

Yes, engine monitoring should highlight longer term issues long before they become a problem, so I don't expect we will see engines failing spontaneously in 2 or 3 months time. I just hope we don't have repair bills which cripple the industry more than another couple of days of waiting for the ash to clear would have done. And an engine change takes a lot longer than 2 days....

CaptainPaddy

Although the Volcanic Eruptions have declined slightly the low ash levels have remained constant over the UK and are forecast to remain so for the remaining of this week.

Paddy on the previous zero tolerance levels you seem to support we would be in over two weeks of no fly! not a couple of days longer as you put it.
Taken from the metoffice

Pace

Are you sure about that? the UK has looked completely clear for some time according to the Met office.
The wind direction is also favourably predicted for the UK until Saturday or so.

lomapaseo

I was using the word premature in the sense of earlier than expected. Whether that is measured in simple engine running hours or cycles would depend on what is normal for the particular engine.

By 'certain' contaminants I was referring to those that at HPT blade temperatures change their nature to a 'glass' like material that has been known to flow and coat surfaces.

Sadly I think this whole situation is one of those 'where we know what we don't know'

I would not like to be thought of as a doom-monger just as somebody who does not know enough to make a flight safety based commercial decision on this topic - sometimes it is great being retired!

Is it just me or has anybody else noticed that the clouds have a brownish tinge to them? Just my observation whilst flying down T9 to the Canaries on Friday morning. It also may just be a coincidence but the whole of the cabin and flight deck stank very strongly of burning paper on engine shut down on stand.
The cabin crew senior reported the fumes to be like someone had just struck a box full of matches, all the passengers were very concerned. Duration of the fumes lasted about 7 to 8 minutes and I opened the DV to get fresh air into the flight deck. The engineer could not find anything obvious after a thorough inspection, neither could I during the walk round

The same thing happened the next day on the sane aircraft.

BR.

I still haven't seen a reply to what was different about this eruption compared to the thousands of others that have happened since the advent of turbine engines, which have had no ill effects reported beyond a few where the aircraft was actually close enough to be visual with the eruption, and which were avoided by all other aircraft by common sense rather than a continent-wide ban.

When Mount St. Helens blew in 1980, for example, the ash generated was so thick that snowploughs had to be deployed on roads well downwind, yet there were only local aviation closures and diversions, and no adverse effects were reported from the continuing use of other airports and airways beyond the immediate and obvious zone. Why was a different approach taken this time, and what was the basis for it ?

Unfortunately this thread has deteriorated into a series of hypothetical arguments between 3 or 4 protagonists on one side and most of the aviation society on the other. Some people do not seem to be able to differentiate between risk, safety, commercial decisions, personal choice and living life as a human being. Sorry to bring Capt. Moody up again, but since his encounter with volcanic ash, many people have unfortunately been killed in aircraft accidents of one sort or another, but none to my knowledge as a result of their jet being affected by said ash. Even though it, or ash like it has been present in the air ever since.
Engineering, and especially engine monitoring, has moved on leaps and bounds in the last 30 years and that leads directly to safer flying and also (believe it or not) better commercial decisions and therefore cost saving, which in turn is passed onto passengers.
From the moment you are born life is a risk and when you become old enough to make your own decisions then your risk assessment of a situation will determine the way you live that life. Unless you are a deportee, nobody will ever be forced to get on an aircraft. If you feel the aircraft is unsafe and don't want to travel that is a decision for the individual, but please leave commercial decisions about engine life etc. to the people who have the data in front of them and not a rumour forum.
Now mind how you drive home because in the last 25 years nobody has been killed in the air by volcanic ash, but 100 000 people have been killed on UK roads. What's the difference in risk involved in that?

When I last took a bird, it most definitely WAS centrifuged (and diced).