Bali Flights Cancelled due to Lewotobi Volcano

So the Darwin VACC envelopes appear to be some 'call' on the density of the ash plume, but they don't say what the criteria is; probably includes infra-red and other spectra to determine a 'safe' level. Never-the-less you can tell from FR24 that any plane flying into or out of DPS will encounter some ash.

View attachment 415072

If anyone has info on the methodology of the Darwin VAAC, particularly on what they use to define their envelopes, it would be interesting to know.
Following the 2010 Iceland volcanic disruption in Europe, the UK CAA decided that 4 milligrams of ash per cubic metre of air was "safe". Not sure if that determination has spread past the UK.
 
Following the 2010 Iceland volcanic disruption in Europe, the UK CAA decided that 4 milligrams of ash per cubic metre of air was "safe". Not sure if that determination has spread past the UK.

IF I understand the concept of 'mass flow rate' in kg/sec being the mass of air that passes through a compressor/engine per second (will vary a lot of course) and a GE-90 engine (largest in use? on B777) has a max MFR of 1,350kg/sec source (opens a PDF) , and the density of air is 1.3 kg/m3 at sea level and 0.55 at 25,000 ft (so 2,450m3/sec ) then it will ingest about 9kg of ash per second using the smaller figure. Hmmm ..that doesn't sound right; as if 6kg/sec would be OK? That's a lot of potential melt to adhere to the turbine blades etc.

@jb747 would you care to tell me where I'm going wrong or what are the relevant factors that would determine safe levels of ash in the air?

Note - I'm not suggesting any VAAC guidance is wrong, just trying to figure out some of the physical parameters of ash Vs engine.
 
Envelope is increasing again. Not sure what the deciding factor is for the airlines to stop again, certainly any breach past 117E would seem probable. We shall see what the winds do overnight and tomorrow mornings update will be interesting.
IMG_5715.png
 
Anyone tracking eruptions from Lewotobi?

Is there a website tracking this?
Obviously further eruptions will provide more sky high ash.
 
Last edited:

We are closely monitoring the volcanic ash cloud caused by Mount Lewotobi in Indonesia. There is no impact to Qantas flights at this stage and based on current forecasts, our afternoon flights are scheduled to operate as normal.

We are monitoring the situation closely and will continue to keep customers updated.
 

We are closely monitoring the volcanic ash cloud caused by Mount Lewotobi in Indonesia. There is no impact to Qantas flights at this stage and based on current forecasts, our afternoon flights are scheduled to operate as normal.

We are monitoring the situation closely and will continue to keep customers updated.
Yes, I just saw that banner. Didn’t even know about the eruption otherwise…
 
Read our AFF credit card guides and start earning more points now.

AFF Supporters can remove this and all advertisements


Write your reply...

Become an AFF member!

Join Australian Frequent Flyer (AFF) for free and unlock insider tips, exclusive deals, and global meetups with 65,000+ frequent flyers.

AFF members can also access our Frequent Flyer Training courses, and upgrade to Fast-track your way to expert traveller status and unlock even more exclusive discounts!

AFF forum abbreviations

Wondering about Y, J or any of the other abbreviations used on our forum?

Check out our guide to common AFF acronyms & abbreviations.
Back
Top