Plain English Meaning
The phrase one pilot says to clearly tell the other pilot, 'I am now flying the aircraft.' It removes any doubt about who is in charge of the controls at that moment.
Full Definition
A standard verbal phrase used during flight training to formally accept control of the aircraft from the other pilot, completing the second step of the FAA's three-step positive exchange of flight controls procedure.
Context Anchor
Used between an instructor and student, or between two pilots, whenever one person takes over control of the aircraft.
Why Pilots Care
Prevents confusion about who is flying and maintains safety during training handovers.