What Is Top of Descent? Definition & Meaning in Aviation
The top of descent is the point at which an aircraft leaves its cruise altitude and begins its descent towards the destination.
In plain language
Pilots plan it so the aircraft arrives at the right height and speed. A common rule of thumb is about 3 nautical miles of distance for every 1,000 feet to lose.
Example
An aircraft cruising at 35,000 feet may begin its descent roughly 100 nautical miles from the airport.
Why it matters
The top of descent is when your flight starts getting ready to land. On a tracker, a steady drop in altitude far from the airport marks it, and it is a useful clue for estimating arrival.