What is Heading Select in Aviation? Heading Select, commonly abbreviated as HDG SEL, is a fundamental autopilot function used to control an aircraft’s directional heading. It allows pilots to manually set and maintain a specific heading via the autopilot system, simplifying navigation and reducing pilot workload during flight. This feature is especially important in commercial, general aviation, and even some unmanned aerial vehicles, where precision and ease of control are paramount.
What is Heading Select (HDG SEL) and How It Works
Heading Select or HDG SEL is an autopilot mode that lets pilots command the aircraft to maintain a specific heading based on a preset value. When activated, the autopilot aligns the aircraft’s lateral navigation to the chosen heading marked on the heading indicator or horizontal situation indicator (HSI). This means the aircraft will turn and maintain the heading without the need for continuous manual input from the pilot.
The implementation of HDG SEL is commonly found in most modern avionics suites, including Garmin G1000, Honeywell Primus Epic, and Boeing 737 flight control systems. The heading is usually selected via a rotating knob on the control panel that adjusts the heading bug on the compass rose. When the HDG SEL mode activates, the autopilot commands the ailerons and rudder to bank and hold the aircraft at the designated heading. Typical bank angles commanded by the autopilot in this mode range from 10° to 25°, depending on the aircraft and autopilot settings.
Applications of Heading Select in Aviation
Heading Select is widely used in several phases of flight, including enroute navigation, departure, arrival, and holding patterns. It enables pilots to intercept and track airways or departures and arrivals procedures accurately without disengaging autopilot. This capability ensures more precise adherence to air traffic control (ATC) clearances and improves safety and operational efficiency.
One particular application of Heading Select is during a holding pattern. ATC may instruct a pilot to “hold on the heading of 180 degrees,” which is easily accomplished by setting that heading in HDG SEL mode, allowing the pilot to focus on altitude and timing. Furthermore, after completing an instrument approach, the pilot can use HDG SEL to transition from lateral navigation (LNAV) back to a manual heading, facilitating better control during visual segments or taxiing. This flexibility makes HDG SEL indispensable in both IFR (Instrument Flight Rules) and VFR (Visual Flight Rules) conditions.
Technical Details and Advantages of Heading Select (HDG SEL)
Heading Select (HDG SEL) relies on inputs from the aircraft’s magnetic compass or inertial heading reference system (HRS). The HDG SEL function interacts with the autopilot’s lateral mode to maintain the selected heading through continuous lateral control inputs. In commercial aircraft, these autopilots typically operate with a servo system commanding control surfaces with a latency under 100 milliseconds, ensuring smooth and accurate heading corrections.
