We’ve heard a lot about the issue of bird strikes on aircraft lately.
Today’s invention is to equip all airliners each with a small rocket (attached to the tailfin, perhaps) and enough propellant to enable them to make a powered descent in the event that all of their jets are disabled by ingestion of flocks of birds.
The rocket would fire only when sensors indicated this condition and it could be designed for single-use, thus decreasing cost and weight of this bolt-on system. To decrease weight still further, the rocket might make use of atmospheric oxygen, rather than on-board oxidants…inefficient ignition might actually be an advantage here, allowing for a more controllable burn.