Definition
The specific indicated airspeed selected and maintained by the pilot during a descent, chosen to suit the type of descent being flown (such as a normal en route descent, an approach descent, or an emergency descent) and consistent with the aircraft's operating limitations and procedures.
Plain English
The speed the pilot decides to fly at while going down, picked to match the kind of descent and stay within what the aircraft is built to handle.
Context Anchor
Seen when entering or maintaining a descent in instrument flight, especially while adjusting power and nose position from level flight.
Derivation
“Descent” comes from a Latin root meaning “to climb down.” “Airspeed” means speed through the air, not speed over the ground. Together, the term points to the aircraft’s speed through the air during a controlled move to a lower altitude.
Why Pilots Care
Maintaining the correct descent airspeed ensures proper control, predictable descent rate, and compliance with approach or enroute requirements.
Intuition Check
Do not read descent airspeed as “how fast the airplane is going downward.” It means forward speed through the air while descending; how quickly altitude is being lost is a separate idea.
Example Sentence 1
Before starting down from cruise, the pilot reduced power slightly and let the airplane settle at the planned descent airspeed.
Example Sentence 2
During the enroute descent the crew held 250 knots as the published descent airspeed.