reached by or to be leveled by
What does it mean by 'by'? is it the same as 'at or before' or just 'at' in terms of ATC or aviation intentions.
We've been discussing a lot by this specifically exact meaning since almost every time it seems that Heathrow control says the word.
Many thanks.
BTW, I used to be cleared by Paris DG approach just a phraseology 'history landing' and everyone in the cockpit just turned to see each other in the faces and be hilarious how easy she was.