diff --git a/Tools/autotest/ArduPlane_Tests/FlyEachFrame/basic-quadplane.txt b/Tools/autotest/ArduPlane_Tests/FlyEachFrame/basic-quadplane.txt
index d4ec44c2e0..af7a9afbf3 100644
--- a/Tools/autotest/ArduPlane_Tests/FlyEachFrame/basic-quadplane.txt
+++ b/Tools/autotest/ArduPlane_Tests/FlyEachFrame/basic-quadplane.txt
@@ -1,13 +1,14 @@
 QGC WPL 110
 0	0	0	16	0.000000	0.000000	0.000000	0.000000	-35.363262	149.165237	584.390015	1
-1	0	3	84	0.000000	0.000000	0.000000	0.000000	-35.361279	149.164230	30.000000	1
-2	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361229	149.163025	80.000000	1
-3	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364563	149.163773	80.000000	1
-4	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364384	149.164795	80.000000	1
-5	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361027	149.164093	80.000000	1
-6	0	0	177	2.000000	1.000000	0.000000	0.000000	0.000000	0.000000	0.000000	1
-7	0	3	189	0.000000	0.000000	0.000000	0.000000	-35.362915	149.162613	60.000000	1
-8	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.363136	149.162750	60.000000	1
-9	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365467	149.164215	55.000000	1
-10	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365009	149.165482	39.889999	1
-11	0	3	85	0.000000	0.000000	0.000000	1.000000	-35.363041	149.165222	0.000000	1
+1	0	0	223	1.000000	0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	1
+2	0	3	84	0.000000	0.000000	0.000000	0.000000	-35.361279	149.164230	30.000000	1
+3	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361229	149.163025	80.000000	1
+4	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364563	149.163773	80.000000	1
+5	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364384	149.164795	80.000000	1
+6	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361027	149.164093	80.000000	1
+7	0	0	177	2.000000	1.000000	0.000000	0.000000	0.000000	0.000000	0.000000	1
+8	0	3	189	0.000000	0.000000	0.000000	0.000000	-35.362915	149.162613	60.000000	1
+9	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.363136	149.162750	60.000000	1
+10	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365467	149.164215	55.000000	1
+11	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365009	149.165482	39.889999	1
+12	0	3	85	0.000000	0.000000	0.000000	1.000000	-35.363041	149.165222	0.000000	1
diff --git a/Tools/autotest/ArduPlane_Tests/FlyEachFrame/basic.txt b/Tools/autotest/ArduPlane_Tests/FlyEachFrame/basic.txt
index b6a88b10c2..51f0935066 100644
--- a/Tools/autotest/ArduPlane_Tests/FlyEachFrame/basic.txt
+++ b/Tools/autotest/ArduPlane_Tests/FlyEachFrame/basic.txt
@@ -1,13 +1,14 @@
 QGC WPL 110
 0	0	0	16	0.000000	0.000000	0.000000	0.000000	-35.363262	149.165237	584.390015	1
-1	0	3	22	15.000000	0.000000	0.000000	0.000000	-35.361279	149.164230	30.000000	1
-2	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361229	149.163025	80.000000	1
-3	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364563	149.163773	80.000000	1
-4	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364384	149.164795	80.000000	1
-5	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361027	149.164093	80.000000	1
-6	0	0	177	2.000000	1.000000	0.000000	0.000000	0.000000	0.000000	0.000000	1
-7	0	3	189	0.000000	0.000000	0.000000	0.000000	-35.362915	149.162613	60.000000	1
-8	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.363136	149.162750	60.000000	1
-9	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365467	149.164215	55.000000	1
-10	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365009	149.165482	39.889999	1
-11	0	3	21	0.000000	0.000000	0.000000	1.000000	-35.363041	149.165222	0.000000	1
+1	0	0	223	1.000000	0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	1
+2	0	3	22	15.000000	0.000000	0.000000	0.000000	-35.361279	149.164230	30.000000	1
+3	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361229	149.163025	80.000000	1
+4	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364563	149.163773	80.000000	1
+5	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364384	149.164795	80.000000	1
+6	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361027	149.164093	80.000000	1
+7	0	0	177	2.000000	1.000000	0.000000	0.000000	0.000000	0.000000	0.000000	1
+8	0	3	189	0.000000	0.000000	0.000000	0.000000	-35.362915	149.162613	60.000000	1
+9	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.363136	149.162750	60.000000	1
+10	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365467	149.164215	55.000000	1
+11	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365009	149.165482	39.889999	1
+12	0	3	21	0.000000	0.000000	0.000000	1.000000	-35.363041	149.165222	0.000000	1
diff --git a/Tools/autotest/arducopter.py b/Tools/autotest/arducopter.py
index fe808916d4..372bd1b7da 100644
--- a/Tools/autotest/arducopter.py
+++ b/Tools/autotest/arducopter.py
@@ -9462,9 +9462,6 @@ class AutoTestCopter(vehicle_test_suite.TestSuite):
                 self.progress("Actually, no I'm not - it is an external simulation")
                 continue
             model = frame_bits.get("model", frame)
-            # the model string for Callisto has crap in it.... we
-            # should really have another entry in the vehicleinfo data
-            # to carry the path to the JSON.
             defaults = self.model_defaults_filepath(frame)
             if not isinstance(defaults, list):
                 defaults = [defaults]
diff --git a/Tools/autotest/arduplane.py b/Tools/autotest/arduplane.py
index 0fe87ca3d8..2aa1390402 100644
--- a/Tools/autotest/arduplane.py
+++ b/Tools/autotest/arduplane.py
@@ -4200,9 +4200,7 @@ class AutoTestPlane(vehicle_test_suite.TestSuite):
         vinfo = vehicleinfo.VehicleInfo()
         vinfo_options = vinfo.options[self.vehicleinfo_key()]
         known_broken_frames = {
-            "plane-tailsitter": "does not take off; immediately emits 'AP: Transition VTOL done' while on ground",
-            "plane-ice" : "needs ICE control channel for ignition",
-            "quadplane-ice" : "needs ICE control channel for ignition",
+            "plane-tailsitter": "unstable in hover; unflyable in cruise",
             "quadplane-can" : "needs CAN periph",
             "stratoblimp" : "not expected to fly normally",
             "glider" : "needs balloon lift",
@@ -4219,11 +4217,7 @@ class AutoTestPlane(vehicle_test_suite.TestSuite):
                 self.progress("Actually, no I'm not - it is an external simulation")
                 continue
             model = frame_bits.get("model", frame)
-            # the model string for Callisto has crap in it.... we
-            # should really have another entry in the vehicleinfo data
-            # to carry the path to the JSON.
-            actual_model = model.split(":")[0]
-            defaults = self.model_defaults_filepath(actual_model)
+            defaults = self.model_defaults_filepath(frame)
             if not isinstance(defaults, list):
                 defaults = [defaults]
             self.customise_SITL_commandline(
diff --git a/Tools/autotest/default_params/plane-ice.parm b/Tools/autotest/default_params/plane-ice.parm
index e6cb59cad0..48c2fb0b96 100644
--- a/Tools/autotest/default_params/plane-ice.parm
+++ b/Tools/autotest/default_params/plane-ice.parm
@@ -1,5 +1,6 @@
 ICE_ENABLE 1
 ICE_RPM_CHAN 1
+ICE_RPM_THRESH 50
 SERVO13_FUNCTION 67
 SERVO14_FUNCTION 69
 RC11_OPTION 179
diff --git a/libraries/AP_Proximity/AP_Proximity_LD06.cpp b/libraries/AP_Proximity/AP_Proximity_LD06.cpp
index 409a3352e3..88d5f5b4f3 100644
--- a/libraries/AP_Proximity/AP_Proximity_LD06.cpp
+++ b/libraries/AP_Proximity/AP_Proximity_LD06.cpp
@@ -92,21 +92,33 @@ void AP_Proximity_LD06::get_readings()
     // Loops through all bytes that were received
     while (nbytes-- > 0) {
 
-        // Gets and logs the current byte being read
-        const uint8_t c = _uart->read();
+        uint8_t c;
+        if (!_uart->read(c)) {
+            break;
+        }
 
         // Stores the byte in an array if the byte is a start byte or we have already read a start byte
-        if (c == LD_START_CHAR || _response_data) {
-
-            // Sets to true if a start byte has been read, default false otherwise
-            _response_data = true;
-
+        if (c == LD_START_CHAR || _byte_count) {
             // Stores the next byte in an array
             _response[_byte_count] = c;
+            if (_byte_count < START_DATA_LENGTH) {
+                _byte_count++;
+                continue;
+            }
+
+            const uint32_t total_packet_length = _response[START_DATA_LENGTH] + 3;
+            if (total_packet_length > ARRAY_SIZE(_response)) {
+                // invalid packet received; throw away all data and
+                // start again.
+                _byte_count = 0;
+                _uart->discard_input();
+                break;
+            }
+
             _byte_count++;
 
-            if (_byte_count == _response[START_DATA_LENGTH] + 3) {
-                
+            if (_byte_count == total_packet_length) {
+
                 const uint32_t current_ms = AP_HAL::millis();
 
                 // Stores the last distance taken, used to reduce number of readings taken
@@ -121,7 +133,6 @@ void AP_Proximity_LD06::get_readings()
 
                 // Resets the bytes read and whether or not we are reading data to accept a new payload
                 _byte_count = 0;
-                _response_data = false;
             }
         }
     }
diff --git a/libraries/AP_Proximity/AP_Proximity_LD06.h b/libraries/AP_Proximity/AP_Proximity_LD06.h
index c51adbb102..af8bd37edd 100644
--- a/libraries/AP_Proximity/AP_Proximity_LD06.h
+++ b/libraries/AP_Proximity/AP_Proximity_LD06.h
@@ -57,7 +57,6 @@ private:
 
     // Store and keep track of the bytes being read from the sensor
     uint8_t _response[MESSAGE_LENGTH_LD06];
-    bool _response_data;
     uint16_t _byte_count;
 
     // Store for error-tracking purposes