According to this Wikipedia article, cabin pressure is normally maintained at 75kPa. The article suggests that at this pressure it would be difficult or impossible to maintain an open flame due to low oxygen concentrations (supposedly comparable to 15% oxygen in standard conditions). Obviously, things can still smolder, oxidize and overheat, not to mention non-gaseous oxidizers.
My basic question is: could a passenger who smuggled a regular butane lighter past security actually manage to light it after reaching cruising altitude, or would it just produce sparks?
clarification/details: this question from aviation.SE suggests 75kPa is a reasonable minimum, so let's assume that is the exact cabin pressure for this question. so the question becomes, will any mixture of butane, nitrogen and oxygen ignite into a flame if the ratio of nitrogen to oxygen is 78:21 (normal earth atmosphere) and the pressure is 75kPa. if not, then how low does the pressure have to get before the oxygen density is to low to outpace the heat lost to convection?