diff --git a/target_simulator/gui/ppi_display.py b/target_simulator/gui/ppi_display.py
index a94032d..f0bc515 100644
--- a/target_simulator/gui/ppi_display.py
+++ b/target_simulator/gui/ppi_display.py
@@ -172,9 +172,13 @@ class PPIDisplay(ttk.Frame):
             # 2. Calculate vector displacement in Cartesian from heading
             # Heading is defined as degrees clockwise from North (0 = North),
             # so the unit vector in Cartesian (East, North) is (sin(h), cos(h)).
-            hdg_rad = math.radians(target.current_heading_deg)
-            dx_nm = vector_len_nm * math.sin(hdg_rad)
-            dy_nm = vector_len_nm * math.cos(hdg_rad)
+            # Invert the sign of the heading angle for plotting so the
+            # drawn heading arrow follows the same angular convention used
+            # for positions (theta_plot = -azimuth). Using -heading here
+            # ensures left/right orientation matches the displayed azimuth.
+            hdg_rad_plot = math.radians(-target.current_heading_deg)
+            dx_nm = vector_len_nm * math.sin(hdg_rad_plot)
+            dy_nm = vector_len_nm * math.cos(hdg_rad_plot)
             
             # 3. Find end point in Cartesian
             x_end_nm = x_start_nm + dx_nm