diff --git a/libraries/SITL/SIM_Aircraft.cpp b/libraries/SITL/SIM_Aircraft.cpp
index f2620a8460..6ad31a1173 100644
--- a/libraries/SITL/SIM_Aircraft.cpp
+++ b/libraries/SITL/SIM_Aircraft.cpp
@@ -298,9 +298,9 @@ void Aircraft::sync_frame_time(void)
 
     uint32_t now_ms = last_wall_time_us / 1000ULL;
     float dt_wall = (now_ms - last_fps_report_ms) * 0.001;
-    if (dt_wall > 2.0) {
+    if (dt_wall > 0.01) {  // 0.01s average
+        achieved_rate_hz = (frame_counter - last_frame_count) / dt_wall;
 #if 0
-        const float achieved_rate_hz = (frame_counter - last_frame_count) / dt_wall;
         ::printf("Rate: target:%.1f achieved:%.1f speedup %.1f/%.1f\n",
                  rate_hz*target_speedup, achieved_rate_hz,
                  achieved_rate_hz/rate_hz, target_speedup);
@@ -471,14 +471,16 @@ void Aircraft::fill_fdm(struct sitl_fdm &fdm)
 // @Field: VE: Velocity east
 // @Field: VD: Velocity down
 // @Field: As: Airspeed
+// @Field: ASpdU: Achieved simulation speedup value
         Vector3d pos = get_position_relhome();
         Vector3f vel = get_velocity_ef();
-        AP::logger().WriteStreaming("SIM2", "TimeUS,PN,PE,PD,VN,VE,VD,As",
-                                    "Qdddffff",
+        AP::logger().WriteStreaming("SIM2", "TimeUS,PN,PE,PD,VN,VE,VD,As,ASpdU",
+                                    "Qdddfffff",
                                     AP_HAL::micros64(),
                                     pos.x, pos.y, pos.z,
                                     vel.x, vel.y, vel.z,
-                                    airspeed_pitot);
+                                    airspeed_pitot,
+                                    achieved_rate_hz/rate_hz);
     }
 }
 
diff --git a/libraries/SITL/SIM_Aircraft.h b/libraries/SITL/SIM_Aircraft.h
index 645f78c7fc..04ef0e946a 100644
--- a/libraries/SITL/SIM_Aircraft.h
+++ b/libraries/SITL/SIM_Aircraft.h
@@ -225,6 +225,7 @@ protected:
     uint64_t frame_time_us;
     uint64_t last_wall_time_us;
     uint32_t last_fps_report_ms;
+    float achieved_rate_hz;  // achieved speedup rate
     int64_t sleep_debt_us;
     uint32_t last_frame_count;
     uint8_t instance;