diff --git a/ArduCopter/Copter.cpp b/ArduCopter/Copter.cpp
index a6dfc5058f..ff0fa5ae54 100644
--- a/ArduCopter/Copter.cpp
+++ b/ArduCopter/Copter.cpp
@@ -491,6 +491,9 @@ void Copter::loop_rate_logging()
     if (should_log(MASK_LOG_ATTITUDE_FAST) && !copter.flightmode->logs_attitude()) {
         Log_Write_Attitude();
     }
+    if (should_log(MASK_LOG_FTN_FAST)) {
+        AP::ins().write_notch_log_messages();
+    }
 }
 
 // ten_hz_logging_loop
@@ -703,7 +706,9 @@ void Copter::update_altitude()
 
     if (should_log(MASK_LOG_CTUN)) {
         Log_Write_Control_Tuning();
-        AP::ins().write_notch_log_messages();
+        if (!should_log(MASK_LOG_FTN_FAST)) {
+            AP::ins().write_notch_log_messages();
+        }
 #if HAL_GYROFFT_ENABLED
         gyro_fft.write_log_messages();
 #endif
diff --git a/ArduCopter/Parameters.cpp b/ArduCopter/Parameters.cpp
index f9494a0e6a..1b44bd2c7b 100644
--- a/ArduCopter/Parameters.cpp
+++ b/ArduCopter/Parameters.cpp
@@ -322,7 +322,7 @@ const AP_Param::Info Copter::var_info[] = {
     // @Param: LOG_BITMASK
     // @DisplayName: Log bitmask
     // @Description: 4 byte bitmap of log types to enable
-    // @Bitmask: 0:ATTITUDE_FAST,1:ATTITUDE_MED,2:GPS,3:PM,4:CTUN,5:NTUN,6:RCIN,7:IMU,8:CMD,9:CURRENT,10:RCOUT,11:OPTFLOW,12:PID,13:COMPASS,14:INAV,15:CAMERA,17:MOTBATT,18:IMU_FAST,19:IMU_RAW,20:VideoStabilization
+    // @Bitmask: 0:ATTITUDE_FAST,1:ATTITUDE_MED,2:GPS,3:PM,4:CTUN,5:NTUN,6:RCIN,7:IMU,8:CMD,9:CURRENT,10:RCOUT,11:OPTFLOW,12:PID,13:COMPASS,14:INAV,15:CAMERA,17:MOTBATT,18:IMU_FAST,19:IMU_RAW,20:VideoStabilization,21:Fast harmonic notch updates
     // @User: Standard
     GSCALAR(log_bitmask,    "LOG_BITMASK",          DEFAULT_LOG_BITMASK),
 
diff --git a/ArduCopter/defines.h b/ArduCopter/defines.h
index 27296c21b5..37684bc398 100644
--- a/ArduCopter/defines.h
+++ b/ArduCopter/defines.h
@@ -144,6 +144,7 @@ enum LoggingParameters {
 #define MASK_LOG_IMU_FAST               (1UL<<18)
 #define MASK_LOG_IMU_RAW                (1UL<<19)
 #define MASK_LOG_VIDEO_STABILISATION    (1UL<<20)
+#define MASK_LOG_FTN_FAST               (1UL<<21)
 #define MASK_LOG_ANY                    0xFFFF
 
 // Radio failsafe definitions (FS_THR parameter)