Obviously, I was curious about this issue before SF1K's post, and I remain so. It occurred to me that, judging by the mileage earned on SIN-DPS (about 1000) and what little I know about Yogyakarta's location vaguely in eastern Java, 500 miles seemed a little high. Consulting the Great Circle Mapper system yielded the following:

From To Distance
DPS (08°44'53"S 115°10'02"E) JOG (07°47'17"S 110°25'54"E) 331 mi

Granted, Yogyakarta is about 20 miles from the volcano, but Ngurah Rai International Airport is located pretty much in the middle of the tourist areas of Bali (Juta, Legian, Seminyak, and Ubud to the North; Jimbaran and Nusa Dua to the South), so the 331 miles should be a good yardstick.

So SF1K has raised a serious question. Does anyone have any first-hand knowledge?