A lot of light aircraft carry whole-plane parachutes, but there's a huge difference between light aircraft and commercial jetliners. One of the heaviest loads e

A lot of light aircraft carry whole-plane parachutes, but there's a huge difference between light aircraft and commercial jetliners. One of the heaviest loads ever dropped was a Minuteman missile in the 70s at about 86,000 pounds. NASA's Ares test drops were for a 72,000 pound load. The 787-9's maximum take-off weight is about 557,000 pounds. A 747 is worse. The 787 would require multiple round chutes with a total area equivalent to 4.8 football fields. A detachable cabin might lower the overall weight considerably, but it's still significantly more than the heaviest loads that have ever been dropped. Engineering a cabin to be detached in a controlled manner at the gate, sitting nicely on the ground with nary a care in the world, while still a difficult engineering problem, is considerably easier than engineering a cabin that can be rapidly detached at altitude safely. It would be hideously more complex, and in all likelihood, that complexity would increase the potential for a catastrophic accident while airborne. Planes are kept relatively simple, despite their actual complexity, for a reason. So it's unlikely that whole-plane parachutes would actually save lives with jetliners. Light aircraft incidents are much more common, and they're small enough to benefit significantly from a parachute.