In older versions: you can fly a few blocks up, then point to the block you want to dig down, and start to fly down and rapidly digdown (you can reach bedrock layer in 14 seconds on sea level)
In this and possibly future versions: this does not work. It is very unconvient. You can only do the standard digdown procedure: reaching bedrock layer in nearly 1 minute. That is impressively slow. FIX IT

NOTE: I STRICTLY DO NOT WANT THIS CONSIDERED AS A REMOVED FEATURE THAT IS, NOT AT ALL GOING TO BE IMPLEMENTED AGAIN. IF CONSIDERED AS REMOVED FEATURE, IMPLEMENT THIS BACK INTO THE GAME AND UNTIL THEN YOU MUST NOT WRITE THIS ISSUE STATUS AS 'RUNNING AS USUAL' blah.

你们明白了吗？