.,
Could you explain when the airport is open and there is an ash cloud that on Many occasions Jetstar and Virgin
have not flown while the others have. Is it possible that they don't want to go all the way around as its unprofitable or if they have to divert they have the extra expense ?
That's what a qantas pilot friend has told me however he is very anti Jetstar
Darwin is the nearest Volcanic Ash Advisory Centre (VAAC) in this part of the world. When they observe activity they issue something called a NOTAM (notice to airmen).....
Volcanic Ash Advisories: latest list of reports from all VAAC centers
Each airline management/pilots have discretion on how to deal with those notams as they are only advisory.
Here is a notam issued by them this morning, regarding the ash from Lombok....
'
FVAU0405 at 08:51 UTC, 05/11/15 from ADRM
VA ADVISORY
DTG: 20151105/0900Z
VAAC: DARWIN
VOLCANO: RINJANI 264030
PSN: S0825 E11628
AREA: INDONESIA
SUMMIT ELEV: 3726M
ADVISORY NR: 2015/42
INFO SOURCE: HIMAWARI-8
AVIATION COLOUR CODE: ORANGE
ERUPTION DETAILS: [COLOR="#FF0000"]VA OBS TO FL170 EXT 240NM TO SW AT
05/0820Z.[/COLOR]'
I've deleted most of the info as too technical but highlighted it means that visible ash was observed up to 17,000 ft extending 240 NM from the source in a south west direction.
I'd suggest this was en-route from anywhere in Australia for an aircraft
on descent into Bali/Lombok airports.
It would, as your Qantas friend suggests, mean the A/C would need to carry excess fuel to avoid the ash or face the consequence of diverting to somewhere. Whereas, an A/C from the same direction, but at cruising altitude (30-40,000ft) to another location, would be above the ash plume.
It can also explain why domestic airlines manage....as they know the local area and possibly descending from another direction or probably find going around or even diverting not so onerous...it's up to individual airline management and policy.
