Emergency descent and glideslope
A quection related to those: how much energy is wasted by emergency descent to safe altitudes like 10 000 feet?
An airplane famously glided 85 miles horizontally to Azores with no fuel.
Is rapid descent to 10 000 feet or so a good way to stretch out the remaining glideslope, and how long would it take to glide at a maximally stretched-out glideslope from, say 40 000 feet to 25 000 feet?