What sort of conditions would have to exist for possible methane combustion in planetary atmospheres? The big moon Triton and gas giants like Neptune have high concentrations of methane in their atmospheres and liquid methane on the surface. Would it be possible to ignite the methane with an incendiary device or by a volcanic explosion or something? Could the conditions for this even develop without it happening spontaneously and thus preventing the buildup of appropriate amounts of methane?
As far as I know, there is no oxygen on Titan, so the atmosphere would never ignite.
You’d need a large amount of free oxygen–far, far more than exists on any known gas giant. In our atmosphere, methane won’t ignite if the concentration exceeds its UEL (upper explosive limit) of 15% by volume. Since our air is 20% oxygen, you can readily see you’d need a lot of it on one of these worlds to ignite its methane atmosphere.