Flying through volcanic ash clouds

[rottenray]

Agaricus bisporus writes:
Well, I reckon anyone who doesn't know the difference between "can" and "will" has a serious problem...

Actually, it has. BA Flight 9.

On 24 June 1982, the route was flown by the City of Edinburgh, a 747-236B. The aircraft flew into a cloud of volcanic ash thrown up by the eruption of Mount Galunggung (approximately 180 kilometres (110 mi) south-east of Jakarta, Indonesia), resulting in the failure of all four engines.

Will it happen every time? Prolly not.

We hear so much about airlines being unwilling to spend any money whatsoever regarding safety, I find it odd that a few folks are beating the monkeypoop out of EasyJet for funding this research.

Even if it only helps a little, only helps a few flights stay on schedule, isn't that worth what Easy is willing to put into it?

And really, who cares if they find an answer that really works? They're not going to sit on it 50 years like the USAF or the Royal would. They'll market it and airlines will buy it.

[Heathrow Harry]

Having been through Jakarta Halim just after the BA incident in '82 I can also remember a Singapore Airbus which had hit the cloud - the front fuselage looked like someone had worked it over with steel wire - all the paint gone and some severe surface damage. It was there for several weeks IIRC

[glhcarl]

Having been through Jakarta Halim just after the BA incident in '82 I can also remember a Singapore Airbus which had hit the cloud - the front fuselage looked like someone had worked it over with steel wire - all the paint gone and some severe surface damage. It was there for several weeks IIRC

One other problem that I have not seen mentioned is the damage to the cabin windows. In the early 80's replacement of cabin windows increased rapidly. An investigation revealed that volcanic was caustic and if the windows were not cleaned thoroughly after an encounter with the ash, crazing and delaminating could occurred.

[jcjeant]

Hi,

Under pressure from airlines, EASA proposes to amend the regulations so that flights through the ash clouds are possible under the responsibility of the operators.
Risks are known. They are listed in EASA CRD to NPA 2011-17
http://hub.easa.europa.eu/crt/docs/viewcrdpdf/id_136

The FAA does not agree and indicated very clearly in his comments: EASA should withdraw this proposal for the reasons explained below (page 8):

And this severe remonstrance against the EASA

[Turbine D]

The superheated particles turn to glass inside the engine and stop it dead.

Agaricus bisporus said:

You'd think that with all the bolleaux that the media spout on aviation we'd not do it ourselves in this place. What an utter load of hogwash! Still, it would never do to let facts or accuracy get in the way of a good story, would it?

Actually the volcanic ash does turn into liquid glass once it is heated above its melting point in the combustor. Below is a photo of the Stage 1 HPT nozzle located just aft of the combustor from one of the BA 747 engines. The accumulation you see on the airfoils is melted volcanic ash (glass) solidified spatter.


The photo below is of a CFM56-2 Stage 1 HPT blade from a DC-8 that very briefly encountered a volcanic ash cloud. The leading edge is starting to erode and the cooling holes are starting to clog from the ash dust.

Recognition
Odor. When encountering a volcanic ash cloud, flight crews usually notice a smoky or acrid odor that can smell like electrical smoke, burned dust, or sulfur.
Haze. Most flight crews, as well as cabin crew or passengers, see a haze develop within the airplane. Dust can settle on surfaces.
Changing engine conditions. Surging, torching from the tailpipe, and flameouts can occur. Engine temperatures can change unexpectedly, and a white glow can appear at the engine inlet.
Airspeed. If volcanic ash fouls the pitot tube, the indicated airspeed can decrease or fluctuate erratically.
Pressurization. Cabin pressure can change, including possible loss of cabin pressurization.
Static discharges. A phenomenon similar to St. Elmo's fire or glow can occur. In these instances, blue-colored sparks can appear to flow up the outside of the windshield or a white glow can appear at the leading edges of the wings or at the front of the engine inlets.

TD

[WHBM]

I was thinking of this thread only last week as we entered the circuit for Catania in Sicily, on a good clear day. Mount Etna nicely smoking away (as it usually does) about 10 nm off the port wing.

I just wonder why the ash and lava thrown out from that has long been of little consequence to aviation; when we got to the visitor centre a few days later there was much evidence of the recent eruptions (including one in 1971 which completely overwhelmed the old visitor centre, the tops of which can be seen sticking out from the solidified lava !), and photographs of a huge ash cloud from 2002 taken from the International Space Station. But does anyone remember any disruption from these ? No, thought not.

Regarding the FAA's comments, they had a major experience with the Mount St Helens ash in 1980 (ash so thick that they needed to get the snowploughs out to clear the roads hundreds of miles away), which was well handled and no aviation problems arose. Perhaps those who did the good job then have all been sidelined by a new generation of overcautious bureaucrats.

[John Farley]

WHBM

I see your line of argument but going back to the dates you mention jet engine hot end design was very different (much simpler and ran at lower temperatures) and as a result was much less susceptible to the effects of atmospheric contamination.

Check out the post above yours. You do not have to be in an obviously visible cloud of ash to get those effects.


JF

[The SSK]

From what I remember of the very steep learning curve I was on in April 2010, the specifics of the Icelandic volcano were that the flooding of the lava by the melted glacier caused huge explosions, resulting in very small particle sizes that stayed aloft much longer. Etna's particles are larger and heavier and don't hang around the atmosphere.

[TURIN]

Easy Jet should be in the airline operation business for their stockholders and not in a speculative development and manufacturing business.

Good job BEA didn't feel the same way or we would still be diverting every winter.

Trident Autoland


Yes, yes, I know BEA were a government owned organisation but you get the drift. (no pun intended).

[lomapaseo]

While looking at pics of volcanic ash encounters just remember that they represent the major degree of what is available in photos. Lesser degrees are not easily confirmed as anything more than accumulated everyday encounters with dirt.

EASA was buikding on this in their notice of proposed rule making while attempting to lay the onus on the manufacturers to define some level of wear out vs variable dirt that is OK.

I do use the word dirt because there are plenty of other particles out there other than from volcanos that will produce the same damage in varriable degrees. Accumulation vs time is the key to avoidance.

It is not the attempt to scare pilots to avoid all encounters but rather to alert pilots to minimize the accumulation of damage by controling the time and internal temperatures regarding the engines.

Most of the recomendations in this regard key on overt symptoms that require immediate action. It is anticipated that avoiding these symptoms as much as posible by route changes will allow us to operate safely and effectively.