An answer as I see it is firstly to stop taking the bogans to Bali until Gurung Agung settles down and in the meantime position a big aircraft, say B744 if QF can spare one, to DRW and when the VACC says it will be OK, depart DRW to arrive over DPS about 15 minutes after first light and, subject to the ash not being at DPS, two rotations can be done to DRW during daylight hours to get the bogans out to DRW. That should make a big dent in the problem.