Definition
An electronic signal generated by a Flight Management System (FMS) or navigation computer that tells the autopilot how much to bank the aircraft left or right to follow a programmed course, intercept a track, or fly a curved path such as a turn between waypoints.
Plain English
It is the instruction the navigation computer sends to the autopilot telling it which way to roll, and how steeply, so the aircraft stays on the planned route.
Context Anchor
Seen in instrument flying and flight management system discussions, especially when the navigation system is driving flight director or autopilot guidance.
Derivation
Roll means the aircraft’s banking motion around an imaginary line from nose to tail. Steering means guiding a vehicle. Command means an instruction sent by a person or system. Together, the phrase points to an instruction that guides the aircraft by controlling bank.
Why Pilots Care
Allows the autopilot to make smooth, accurate turns along the programmed route, lowering pilot workload and improving track accuracy.
Grounding Statement
In the cockpit, this is the left-or-right turning guidance the aircraft follows when the correct navigation and autopilot settings are in use.
Intuition Check
Do not read “command” as an air traffic control instruction, and do not read “steering” as a steering wheel action. Here it means an electronic bank instruction from the navigation system to the airplane’s guidance equipment.
Example Sentence 1
With the autopilot in NAV mode, the FMS sent a roll steering command that banked the aircraft into the turn before reaching the waypoint.
Example Sentence 2
During the missed approach, the roll steering command directed a left turn to intercept the published course.