Improve message handling in mavlink IRIDIUM mode

- Do not send any mission updates as they are handled within HIGH_LATENCY2
- Always send a command acknowledge even if transmitting is not enabled

src/modules/mavlink/mavlink_main.cpp

@@ -2236,7 +2236,11 @@ Mavlink::task_main(int argc, char *argv[])
 				msg.target_component = command_ack.target_component;
 				current_command_ack = command_ack.command;
 
+				// always transmit the acknowledge
+				bool _transmitting_enabled_temp = _transmitting_enabled;
+				_transmitting_enabled = true;
 				mavlink_msg_command_ack_send_struct(get_channel(), &msg);
+				_transmitting_enabled = _transmitting_enabled_temp;
 			}
 		}
 

src/modules/mavlink/mavlink_mission.cpp

@@ -479,6 +479,11 @@ MavlinkMissionManager::send_mission_item_reached(uint16_t seq)
 void
 MavlinkMissionManager::send(const hrt_abstime now)
 {
+	// do not send anything over high latency communication
+	if (_mavlink->get_mode() == Mavlink::MAVLINK_MODE_IRIDIUM) {
+		return;
+	}
+
 	bool updated = false;
 	orb_check(_mission_result_sub, &updated);