Definition
A condition in which a jet engine takes longer than normal to spool up from a low power setting to a higher one when the throttle is advanced. It is a known operating characteristic of jet engines, particularly at low rpm, and must be anticipated whenever the pilot needs a rapid increase in thrust.
Plain English
When the pilot pushes the throttle forward, a jet engine does not produce more thrust right away. There is a delay while the engine speeds up, and that delay is longest when the engine is at low power.
Context Anchor
Encountered when learning jet aircraft handling, especially power changes during takeoff, approach, go-around, and recovery from low-thrust flight.
Derivation
Acceleration comes from Latin words meaning “to make quicker.” In this term, it refers to the engine becoming quicker or stronger in output, not the airplane simply moving faster across the ground.
Why Pilots Care
The delay affects go-around timing and obstacle clearance decisions; initiating the maneuver too late can result in insufficient climb performance.
Analogy
Like pressing the accelerator in a heavy truck—the engine takes time to build up power compared with a light sports car.
Grounding Statement
If a jet is descending at low power and the pilot suddenly needs more thrust, the engine may take several seconds to deliver it.
Intuition Check
Do not read this as the airplane accelerating slowly through the air. Here it means the jet engine itself takes time to increase thrust after the pilot asks for more power.
Example Sentence 1
Because of the slow acceleration of the jet engine, the pilot kept the power setting higher than usual on final approach to ensure thrust would be available quickly if a go-around became necessary.
Example Sentence 2
Recognizing the slow acceleration of the jet engine, the pilot advanced the throttles well before reaching the missed-approach point.