Disengaging the Elytra

Why Disengage Elytra? What's the use?
Ladders (and vines, glowberry vines, couple others) cannot be interacted with while Elytra are in use, and the only current way to disangage them is to land. This leads to problems if you accidentally engaged your elytra on your way to or down a ladder, you'll have to continue gliding until a landing block is available, consuming your elytra durability in the process, and often gaining speed above the safe level to land with, sometimes resulting in player deaths.
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How:
By pressing Shift (or whatever button is assigned to crouch) twice in rapid succession.