diff --git a/libraries/AP_AHRS/AP_AHRS.cpp b/libraries/AP_AHRS/AP_AHRS.cpp
index 86f5bb4f9e..49b2a0d85c 100644
--- a/libraries/AP_AHRS/AP_AHRS.cpp
+++ b/libraries/AP_AHRS/AP_AHRS.cpp
@@ -1400,11 +1400,11 @@ bool AP_AHRS::get_mag_field_correction(Vector3f &vec) const
 
 // Get a derivative of the vertical position which is kinematically consistent with the vertical position is required by some control loops.
 // This is different to the vertical velocity from the EKF which is not always consistent with the verical position due to the various errors that are being corrected for.
-bool AP_AHRS::get_vert_pos_rate(float &velocity) const
+bool AP_AHRS::get_vert_pos_rate_D(float &velocity) const
 {
     switch (active_EKF_type()) {
     case EKFType::NONE:
-        return dcm.get_vert_pos_rate(velocity);
+        return dcm.get_vert_pos_rate_D(velocity);
 
 #if HAL_NAVEKF2_AVAILABLE
     case EKFType::TWO:
@@ -1420,11 +1420,11 @@ bool AP_AHRS::get_vert_pos_rate(float &velocity) const
 
 #if AP_AHRS_SIM_ENABLED
     case EKFType::SIM:
-        return sim.get_vert_pos_rate(velocity);
+        return sim.get_vert_pos_rate_D(velocity);
 #endif
 #if HAL_EXTERNAL_AHRS_ENABLED
     case EKFType::EXTERNAL:
-        return external.get_vert_pos_rate(velocity);
+        return external.get_vert_pos_rate_D(velocity);
 #endif
     }
     // since there is no default case above, this is unreachable
diff --git a/libraries/AP_AHRS/AP_AHRS.h b/libraries/AP_AHRS/AP_AHRS.h
index f3cc56f057..5fa7550e1b 100644
--- a/libraries/AP_AHRS/AP_AHRS.h
+++ b/libraries/AP_AHRS/AP_AHRS.h
@@ -229,7 +229,7 @@ public:
 
     // Get a derivative of the vertical position in m/s which is kinematically consistent with the vertical position is required by some control loops.
     // This is different to the vertical velocity from the EKF which is not always consistent with the vertical position due to the various errors that are being corrected for.
-    bool get_vert_pos_rate(float &velocity) const;
+    bool get_vert_pos_rate_D(float &velocity) const;
 
     // write optical flow measurements to EKF
     void writeOptFlowMeas(const uint8_t rawFlowQuality, const Vector2f &rawFlowRates, const Vector2f &rawGyroRates, const uint32_t msecFlowMeas, const Vector3f &posOffset, const float heightOverride);
diff --git a/libraries/AP_AHRS/AP_AHRS_Backend.h b/libraries/AP_AHRS/AP_AHRS_Backend.h
index baa8ef4e7d..6675a9c288 100644
--- a/libraries/AP_AHRS/AP_AHRS_Backend.h
+++ b/libraries/AP_AHRS/AP_AHRS_Backend.h
@@ -177,7 +177,7 @@ public:
 
     // Get a derivative of the vertical position in m/s which is kinematically consistent with the vertical position is required by some control loops.
     // This is different to the vertical velocity from the EKF which is not always consistent with the vertical position due to the various errors that are being corrected for.
-    virtual bool get_vert_pos_rate(float &velocity) const = 0;
+    virtual bool get_vert_pos_rate_D(float &velocity) const = 0;
 
     // returns the estimated magnetic field offsets in body frame
     virtual bool get_mag_field_correction(Vector3f &ret) const WARN_IF_UNUSED {
diff --git a/libraries/AP_AHRS/AP_AHRS_DCM.cpp b/libraries/AP_AHRS/AP_AHRS_DCM.cpp
index 5e053688ee..ce8b038334 100644
--- a/libraries/AP_AHRS/AP_AHRS_DCM.cpp
+++ b/libraries/AP_AHRS/AP_AHRS_DCM.cpp
@@ -1183,7 +1183,7 @@ bool AP_AHRS_DCM::get_velocity_NED(Vector3f &vec) const
 
 // Get a derivative of the vertical position in m/s which is kinematically consistent with the vertical position is required by some control loops.
 // This is different to the vertical velocity from the EKF which is not always consistent with the vertical position due to the various errors that are being corrected for.
-bool AP_AHRS_DCM::get_vert_pos_rate(float &velocity) const
+bool AP_AHRS_DCM::get_vert_pos_rate_D(float &velocity) const
 {
     Vector3f velned;
     if (!get_velocity_NED(velned)) {
diff --git a/libraries/AP_AHRS/AP_AHRS_DCM.h b/libraries/AP_AHRS/AP_AHRS_DCM.h
index 800e7b681c..168cbbaa33 100644
--- a/libraries/AP_AHRS/AP_AHRS_DCM.h
+++ b/libraries/AP_AHRS/AP_AHRS_DCM.h
@@ -111,7 +111,7 @@ public:
 
     // Get a derivative of the vertical position in m/s which is kinematically consistent with the vertical position is required by some control loops.
     // This is different to the vertical velocity from the EKF which is not always consistent with the vertical position due to the various errors that are being corrected for.
-    bool get_vert_pos_rate(float &velocity) const override;
+    bool get_vert_pos_rate_D(float &velocity) const override;
 
     // returns false if we fail arming checks, in which case the buffer will be populated with a failure message
     // requires_position should be true if horizontal position configuration should be checked (not used)
diff --git a/libraries/AP_AHRS/AP_AHRS_External.cpp b/libraries/AP_AHRS/AP_AHRS_External.cpp
index 3d09b8e723..0c1a01b2c7 100644
--- a/libraries/AP_AHRS/AP_AHRS_External.cpp
+++ b/libraries/AP_AHRS/AP_AHRS_External.cpp
@@ -100,7 +100,7 @@ bool AP_AHRS_External::get_velocity_NED(Vector3f &vec) const
     return AP::externalAHRS().get_velocity_NED(vec);
 }
 
-bool AP_AHRS_External::get_vert_pos_rate(float &velocity) const
+bool AP_AHRS_External::get_vert_pos_rate_D(float &velocity) const
 {
     return AP::externalAHRS().get_speed_down(velocity);
 }
diff --git a/libraries/AP_AHRS/AP_AHRS_External.h b/libraries/AP_AHRS/AP_AHRS_External.h
index 5a21cebad1..999ed05fed 100644
--- a/libraries/AP_AHRS/AP_AHRS_External.h
+++ b/libraries/AP_AHRS/AP_AHRS_External.h
@@ -72,7 +72,7 @@ public:
 
     // Get a derivative of the vertical position in m/s which is kinematically consistent with the vertical position is required by some control loops.
     // This is different to the vertical velocity from the EKF which is not always consistent with the vertical position due to the various errors that are being corrected for.
-    bool get_vert_pos_rate(float &velocity) const override;
+    bool get_vert_pos_rate_D(float &velocity) const override;
 
     // returns false if we fail arming checks, in which case the buffer will be populated with a failure message
     // requires_position should be true if horizontal position configuration should be checked (not used)
diff --git a/libraries/AP_AHRS/AP_AHRS_SIM.cpp b/libraries/AP_AHRS/AP_AHRS_SIM.cpp
index 0714d15435..ed6cd01bb8 100644
--- a/libraries/AP_AHRS/AP_AHRS_SIM.cpp
+++ b/libraries/AP_AHRS/AP_AHRS_SIM.cpp
@@ -80,7 +80,7 @@ Vector2f AP_AHRS_SIM::groundspeed_vector(void)
     return Vector2f(fdm.speedN, fdm.speedE);
 }
 
-bool AP_AHRS_SIM::get_vert_pos_rate(float &velocity) const
+bool AP_AHRS_SIM::get_vert_pos_rate_D(float &velocity) const
 {
     if (_sitl == nullptr) {
         return false;
diff --git a/libraries/AP_AHRS/AP_AHRS_SIM.h b/libraries/AP_AHRS/AP_AHRS_SIM.h
index 3caf1051b0..340a8877b6 100644
--- a/libraries/AP_AHRS/AP_AHRS_SIM.h
+++ b/libraries/AP_AHRS/AP_AHRS_SIM.h
@@ -92,7 +92,7 @@ public:
 
     // Get a derivative of the vertical position in m/s which is kinematically consistent with the vertical position is required by some control loops.
     // This is different to the vertical velocity from the EKF which is not always consistent with the vertical position due to the various errors that are being corrected for.
-    bool get_vert_pos_rate(float &velocity) const override;
+    bool get_vert_pos_rate_D(float &velocity) const override;
 
     // returns false if we fail arming checks, in which case the buffer will be populated with a failure message
     // requires_position should be true if horizontal position configuration should be checked (not used)