diff --git a/libraries/GCS_MAVLink/GCS.h b/libraries/GCS_MAVLink/GCS.h
index 10229d42d8..1c89198ad9 100644
--- a/libraries/GCS_MAVLink/GCS.h
+++ b/libraries/GCS_MAVLink/GCS.h
@@ -9,7 +9,6 @@
 #include <AP_Mission/AP_Mission.h>
 #include <stdint.h>
 #include "MAVLink_routing.h"
-#include <AP_Avoidance/AP_Avoidance.h>
 #include <AP_Frsky_Telem/AP_Frsky_Telem.h>
 #include <AP_AdvancedFailsafe/AP_AdvancedFailsafe.h>
 #include <AP_RTC/JitterCorrection.h>
@@ -435,7 +434,6 @@ public:
     virtual void send_position_target_global_int() { };
     virtual void send_position_target_local_ned() { };
     void send_servo_output_raw();
-    static void send_collision_all(const AP_Avoidance::Obstacle &threat, MAV_COLLISION_ACTION behaviour);
     void send_accelcal_vehicle_position(uint32_t position);
     void send_scaled_imu(uint8_t instance, void (*send_fn)(mavlink_channel_t chan, uint32_t time_ms, int16_t xacc, int16_t yacc, int16_t zacc, int16_t xgyro, int16_t ygyro, int16_t zgyro, int16_t xmag, int16_t ymag, int16_t zmag));
     void send_sys_status();
diff --git a/libraries/GCS_MAVLink/GCS_Common.cpp b/libraries/GCS_MAVLink/GCS_Common.cpp
index 9ccbc47c54..cfff492702 100644
--- a/libraries/GCS_MAVLink/GCS_Common.cpp
+++ b/libraries/GCS_MAVLink/GCS_Common.cpp
@@ -2722,27 +2722,6 @@ void GCS_MAVLINK::send_servo_output_raw()
 }
 
 
-void GCS_MAVLINK::send_collision_all(const AP_Avoidance::Obstacle &threat, MAV_COLLISION_ACTION behaviour)
-{
-    for (uint8_t i=0; i<MAVLINK_COMM_NUM_BUFFERS; i++) {
-        if ((1U<<i) & mavlink_active) {
-            mavlink_channel_t chan = (mavlink_channel_t)(MAVLINK_COMM_0+i);
-            if (comm_get_txspace(chan) >= MAVLINK_NUM_NON_PAYLOAD_BYTES + MAVLINK_MSG_ID_COLLISION) {
-                mavlink_msg_collision_send(
-                    chan,
-                    MAV_COLLISION_SRC_ADSB,
-                    threat.src_id,
-                    behaviour,
-                    threat.threat_level,
-                    threat.time_to_closest_approach,
-                    threat.closest_approach_z,
-                    threat.closest_approach_xy
-                    );
-            }
-        }
-    }
-}
-
 void GCS_MAVLINK::send_accelcal_vehicle_position(uint32_t position)
 {
     if (HAVE_PAYLOAD_SPACE(chan, COMMAND_LONG)) {