Fire is the number one killer in airplane mishaps. It doesn't take much of an impact to explode a fuel tank and set a plane on fire. Passengers die from inhaling searing-hot air and from toxic fumes released by burning upholstery or insulation. They die because their legs are broken from slamming into the seat in front of them and they can't crawl to the exits. They die because passengers don't exit flaming planes in an orderly manner; they stampede and elbow and trample. Could airlines do a better job of making their planes fire-safe? You bet they could. They could install more emergency exits, but they won't, because that means taking out seats and losing revenue. They could install sprinkler systems or build crashworthy fuel systems of the type used on military helicopters. But they won't, because both these options would add too much weight. More weight means higher fuel costs.
—Stiff: The Curious Lives of Human Cadavers by Mary Roach













