Own jetpack won't work at extreme height, too cold and no oxigen, but the whole plane might be possible to first eject slowdown parachute at tail then lots of parachute/airbag around the body, thus ATC can override with an emergency brake and shutdown the engine
I think you're underestimating how much parachute you'd need to slow down a jetliner traveling at 600 mph. And a parachute to slow down an entire plane, assuming this was physically and mechanically feasible, would ostensibly be deployed from the cockpit, which makes this a solution that wouldn't have worked in this case, since the co-pilot locked out everyone who didn't want to crash the plane.
When you are taking a car driving course, your instructor can always step on break and stop the car. Air Traffic Control can not do this to an airplane because of safety concern, but if the plane can be safely parachuted, the control of plane can be overridden by ATC, the pilots will have no control over the plane when ATC take over
In fact if ATC can override, parachute is not needed, it can just autopilot the airplane to land on any nearby airport. You only need to code a specific emergency landing sequence in the airplane computer and trigger that sequence when something is wrong. But parachuting is easier than autopilot since it could also solve other problems like computer/engine/gear failure etc...
Would the autopilot be able to land everywhere? Someone said above that it worked on large airports but airports can be different and with different sizes, etc. And maybe it could cause problems for the airport if they weren't ready.
And if you can send information to the plane to do that, or to say it can't land there, can't there be the risk of it being used to hijack the plane? : /