diff --git a/ArduPlane/GCS_Mavlink.cpp b/ArduPlane/GCS_Mavlink.cpp
index 45a596bc6331a8..3f17c961f8a596 100644
--- a/ArduPlane/GCS_Mavlink.cpp
+++ b/ArduPlane/GCS_Mavlink.cpp
@@ -1382,33 +1382,19 @@ void GCS_MAVLINK_Plane::handle_set_position_target_global_int(const mavlink_mess
         
         if (pos_target.type_mask & alt_mask)
         {
-            cmd.content.location.alt = pos_target.alt * 100;
-            cmd.content.location.relative_alt = false;
-            cmd.content.location.terrain_alt = false;
-            switch (pos_target.coordinate_frame) 
-            {
-                case MAV_FRAME_GLOBAL:
-                case MAV_FRAME_GLOBAL_INT:
-                    break; //default to MSL altitude
-                case MAV_FRAME_GLOBAL_RELATIVE_ALT:
-                case MAV_FRAME_GLOBAL_RELATIVE_ALT_INT:
-                    cmd.content.location.relative_alt = true;
-                    break;
-                case MAV_FRAME_GLOBAL_TERRAIN_ALT:
-                case MAV_FRAME_GLOBAL_TERRAIN_ALT_INT:
-                    cmd.content.location.relative_alt = true;
-                    cmd.content.location.terrain_alt = true;
-                    break;
-                default:
-                    gcs().send_text(MAV_SEVERITY_WARNING, "Invalid coord frame in SET_POSTION_TARGET_GLOBAL_INT");
-                    msg_valid = false;
-                    break;
-            }    
+            const int32_t alt_cm = pos_target.alt * 100;
+            Location::AltFrame frame;
+            if (mavlink_coordinate_frame_to_location_alt_frame((MAV_FRAME)pos_target.coordinate_frame, frame)) {
+                gcs().send_text(MAV_SEVERITY_WARNING, "Invalid coord frame in SET_POSTION_TARGET_GLOBAL_INT");
+                msg_valid = false;
+            } else {
+                cmd.content.location.set_alt_cm(alt_cm, frame);
+            }
 
             if (msg_valid) {
                 handle_change_alt_request(cmd);
             }
-        } // end if alt_mask       
+        }
     }
 
 MAV_RESULT GCS_MAVLINK_Plane::handle_command_do_set_mission_current(const mavlink_command_int_t &packet)