Definition
A signal sent through a synchro system that confirms the receiver has moved to the position commanded by the transmitter. The follow-up signal closes the loop by reporting the receiver's actual position back, allowing the system to detect any error between commanded and actual position and drive the receiver until the two match.
Plain English
A signal that says back to the system, 'I've moved to where you told me to go.' It lets the system check that the part being controlled actually reached the position it was sent to.
Context Anchor
Seen in autopilot, flight-control, and aircraft electrical system descriptions, especially when explaining how automatic controls avoid overcorrecting.
Derivation
Follow-up' literally means 'to follow after' — the signal follows after the original command to confirm what happened. The name describes its job: it doesn't initiate action, it reports back on action already commanded.
Why Pilots Care
Ensures the aircraft responds accurately to pilot or autopilot commands without oscillation or lag.
Intuition Check
Do not read “follow-up signal” as a later radio call or a reminder message. Here it means an internal feedback signal that tells an automatic control system how much control movement has already happened.
Example Sentence 1
The synchro receiver in the indicator sends a follow-up signal back to the transmitter, ensuring the displayed position matches the actual position of the flap.
Example Sentence 2
During the control check the technician watched the follow-up signal to confirm the elevator reached the full deflection commanded by the yoke.