diff --git a/src/drivers/gps/ubx.cpp b/src/drivers/gps/ubx.cpp
index 19cf5beecf..c143eeb0c2 100644
--- a/src/drivers/gps/ubx.cpp
+++ b/src/drivers/gps/ubx.cpp
@@ -69,6 +69,9 @@ UBX::UBX(const int &fd, struct vehicle_gps_position_s *gps_position) :
 	_gps_position(gps_position),
 	_configured(false),
 	_waiting_for_ack(false),
+	_got_posllh(false),
+	_got_velned(false),
+	_got_timeutc(false),
 	_disable_cmd_last(0)
 {
 	decode_init();
@@ -275,9 +278,10 @@ UBX::receive(unsigned timeout)
 	bool handled = false;
 
 	while (true) {
+		bool ready_to_return = _configured ? (_got_posllh && _got_velned && _got_timeutc) : handled;
 
 		/* poll for new data, wait for only UBX_PACKET_TIMEOUT (2ms) if something already received */
-		int ret = poll(fds, sizeof(fds) / sizeof(fds[0]), handled ? UBX_PACKET_TIMEOUT : timeout);
+		int ret = poll(fds, sizeof(fds) / sizeof(fds[0]), ready_to_return ? UBX_PACKET_TIMEOUT : timeout);
 
 		if (ret < 0) {
 			/* something went wrong when polling */
@@ -286,7 +290,10 @@ UBX::receive(unsigned timeout)
 
 		} else if (ret == 0) {
 			/* return success after short delay after receiving a packet or timeout after long delay */
-			if (handled) {
+			if (ready_to_return) {
+				_got_posllh = false;
+				_got_velned = false;
+				_got_timeutc = false;
 				return 1;
 
 			} else {
@@ -438,6 +445,7 @@ UBX::handle_message()
 
 					_rate_count_lat_lon++;
 
+					_got_posllh = true;
 					ret = 1;
 					break;
 				}
@@ -447,8 +455,8 @@ UBX::handle_message()
 					gps_bin_nav_sol_packet_t *packet = (gps_bin_nav_sol_packet_t *) _rx_buffer;
 
 					_gps_position->fix_type = packet->gpsFix;
-					_gps_position->s_variance_m_s = packet->sAcc;
-					_gps_position->p_variance_m = packet->pAcc;
+					_gps_position->s_variance_m_s = (float)packet->sAcc * 1e-2f; // from cm/s to m/s
+					_gps_position->p_variance_m = (float)packet->pAcc * 1e-2f; // from cm to m
 					_gps_position->timestamp_variance = hrt_absolute_time();
 
 					ret = 1;
@@ -482,6 +490,7 @@ UBX::handle_message()
 					_gps_position->time_gps_usec += (uint64_t)(packet->time_nanoseconds * 1e-3f);
 					_gps_position->timestamp_time = hrt_absolute_time();
 
+					_got_timeutc = true;
 					ret = 1;
 					break;
 				}
@@ -557,6 +566,7 @@ UBX::handle_message()
 
 					_rate_count_vel++;
 
+					_got_velned = true;
 					ret = 1;
 					break;
 				}
diff --git a/src/drivers/gps/ubx.h b/src/drivers/gps/ubx.h
index 5cf47b60b5..43d6888936 100644
--- a/src/drivers/gps/ubx.h
+++ b/src/drivers/gps/ubx.h
@@ -397,6 +397,9 @@ private:
 	struct vehicle_gps_position_s *_gps_position;
 	bool			_configured;
 	bool			_waiting_for_ack;
+	bool			_got_posllh;
+	bool			_got_velned;
+	bool			_got_timeutc;
 	uint8_t			_message_class_needed;
 	uint8_t			_message_id_needed;
 	ubx_decode_state_t	_decode_state;
diff --git a/src/modules/mavlink/mavlink_main.cpp b/src/modules/mavlink/mavlink_main.cpp
index bb1ad86ef6..28cdf65a3c 100644
--- a/src/modules/mavlink/mavlink_main.cpp
+++ b/src/modules/mavlink/mavlink_main.cpp
@@ -190,8 +190,9 @@ mavlink_send_uart_bytes(mavlink_channel_t channel, const uint8_t *ch, int length
 		/* check if there is space in the buffer, let it overflow else */
 		if (!ioctl(uart, FIONWRITE, (unsigned long)&buf_free)) {
 
-			if (desired > buf_free) {
-				desired = buf_free;
+			if (buf_free < desired) {
+				/* we don't want to send anything just in half, so return */
+				return;
 			}
 		}
 
@@ -222,6 +223,8 @@ Mavlink::Mavlink() :
 	_subscriptions(nullptr),
 	_streams(nullptr),
 	_mission_pub(-1),
+	_mode(MAVLINK_MODE_NORMAL),
+	_total_counter(0),
 	_verbose(false),
 	_forwarding_on(false),
 	_passing_on(false),