The other things that make up an eruption column are typically gases (including water vapor), ambient air that's been entrained and heated, and some lapilli and bomb-sized particles. Some recent news reports have been saying things like "ash and smoke" to describe the Eyjafjallajökull-Fimmvörduháls eruption column, which is incorrect. There is no "smoke" in an eruption column, at least in the sense that most people think of it (as a byproduct of burning materials). The column appears to be smoky, but only because of the presence of the ash, which is generally some shade of gray or black.* (The photo below, from a February 2010 eruption of the Caliente dome at Santiaguito, is quite gray to begin with, but I can guarantee that it's not because something in the vent is burning.)
a flight over Alaska in 1989. No sane pilot is going to fly a plane into that.
So if you're stuck waiting for a flight to or from Europe, just remember: it's a lot better than risking a plane crash. And you can probably look forward to some spectacular sunsets.
*Okay, maybe some lichen is getting toasted, but that still doesn't mean you can call ash "smoke".