While flames in the cabin pretty much assure a bad day, such events are thankfully very rare. Much more common when an in-flight fire erupts are smoke and fumes in the cabin, and they are potential killers.
Carbon monoxide, a byproduct of hydrocarbon combustion, combines with hemoglobin in red blood cells to displace the oxygen they normally carry. Burning fabrics such as wool release toxic cyanide gas, and smoldering plastic can generate hydrochloric acid and phosgene gas (a nerve poison) as well as blinding, thick black smoke.
