Your right, we did not know until we were ready to take the aircraft again(after mx signed it off as a lightbulb problem). We were at FL240 when the aircraft filled with smoke, we all got on O2, and I went looking for the problem, but the smoke was so thick, I could not find the prob. To describe how thick it was, when I got to the bottom of the flight deck, I could not see the Utility res. system, could barely see the Nose emergnecy gear lever in the CC. I could not see so we opened the hatch, cleared all the smoke out, then we could not find the source. turning the AC pack off probably would have been the best decision to start with, but we were passing over the mtns. in Afghanistan, and did not want to wait for it to clear out, for us to be able to see outside.
Mox