Plane: convert next WP alt to global frame in POSITION_TARGET_GLOBAL_INT

ArduPlane/GCS_Mavlink.cpp

@@ -214,6 +214,11 @@ void GCS_MAVLINK_Plane::send_position_target_global_int()
     static constexpr uint16_t TYPE_MASK = POSITION_TARGET_TYPEMASK_VX_IGNORE | POSITION_TARGET_TYPEMASK_VY_IGNORE | POSITION_TARGET_TYPEMASK_VZ_IGNORE |
                                           POSITION_TARGET_TYPEMASK_AX_IGNORE | POSITION_TARGET_TYPEMASK_AY_IGNORE | POSITION_TARGET_TYPEMASK_AZ_IGNORE |
                                           POSITION_TARGET_TYPEMASK_YAW_IGNORE | POSITION_TARGET_TYPEMASK_YAW_RATE_IGNORE | POSITION_TARGET_TYPEMASK_LAST_BYTE;
+    int32_t alt = 0;
+    if (!next_WP_loc.is_zero()) {
+        UNUSED_RESULT(next_WP_loc.get_alt_cm(Location::AltFrame::ABSOLUTE, alt));
+    }
+
     mavlink_msg_position_target_global_int_send(
         chan,
         AP_HAL::millis(), // time_boot_ms
@@ -221,7 +226,7 @@ void GCS_MAVLINK_Plane::send_position_target_global_int()
         TYPE_MASK, // ignore everything except the x/y/z components
         next_WP_loc.lat, // latitude as 1e7
         next_WP_loc.lng, // longitude as 1e7
-        next_WP_loc.alt * 0.01f, // altitude is sent as a float
+        alt * 0.01, // altitude is sent as a float
         0.0f, // vx
         0.0f, // vy
         0.0f, // vz