Definition
The point along a planned descent path at which the descent ends and the aircraft levels off at a lower altitude, typically the altitude required for the next phase of flight such as an approach segment, holding pattern, or cruise level-off.
Plain English
The spot where you stop descending and level out at the new, lower altitude.
Context Anchor
Seen in descent planning, arrival planning, and flight-management computer displays that show where a planned descent should end.
Derivation
Combines 'bottom' (lowest point of a path) with 'descent' from Latin 'descendere' (to climb down). It marks the transition from level cruise to the lowering phase of flight.
Why Pilots Care
Correct timing prevents arriving too high, burning excess fuel, or violating crossing restrictions and approach requirements.
Grounding Statement
Picture a sloping descent line from cruise altitude down to a lower assigned altitude; the bottom-of-descent point is where that sloping line meets the lower altitude.
Intuition Check
Bottom does not mean the lowest point of the entire flight. Here it means the planned end point of a particular descent.
Example Sentence 1
The pilot reduced power and began the descent so the aircraft would reach the bottom-of-descent point exactly at the initial approach fix altitude.
Example Sentence 2
Adjusting speed after passing the bottom-of-descent point allowed a gradual descent that met the published crossing restriction.