diff --git a/MAVProxy/modules/mavproxy_asterix.py b/MAVProxy/modules/mavproxy_asterix.py
index 37e27cf63e..7745daa8d2 100644
--- a/MAVProxy/modules/mavproxy_asterix.py
+++ b/MAVProxy/modules/mavproxy_asterix.py
@@ -4,7 +4,7 @@
 This listens for SDPS on UDP and translates to ADSB_VEHICLE messages
 '''
 
-import pickle
+import json
 from math import *
 
 from MAVProxy.modules.lib import mp_module
@@ -200,12 +200,14 @@ def idle_task(self):
             return
         try:
             if pkt.startswith(b'PICKLED:'):
-                pkt = pkt[8:]
-                # pickled packet
-                try:
-                    amsg = [pickle.loads(pkt)]
-                except pickle.UnpicklingError:
-                    amsg = asterix.parse(pkt)
+                print("bad packet")
+                return
+            if pkt.startswith(b'JSON:'):
+                pkt = pkt[5:]
+                decoded = json.loads(pkt.decode('utf-8'))
+                if not isinstance(decoded, dict):
+                    raise ValueError("JSON packet root is not a dictionary")
+                amsg = [decoded]
             else:
                 amsg = asterix.parse(pkt)
             self.pkt_count += 1
@@ -358,4 +360,3 @@ def init(mpstate):
         #amsg = asterix.parse(pkt)
         #print(amsg)
 
-
diff --git a/MAVProxy/modules/mavproxy_genobstacles.py b/MAVProxy/modules/mavproxy_genobstacles.py
index cf282d288c..c2d84c2876 100644
--- a/MAVProxy/modules/mavproxy_genobstacles.py
+++ b/MAVProxy/modules/mavproxy_genobstacles.py
@@ -2,7 +2,7 @@
 generate dynamic obstacles for OBC 2018
 '''
 
-import time, pickle
+import time, json
 from math import *
 
 from MAVProxy.modules.lib import mp_module
@@ -196,8 +196,8 @@ def update(self, deltat=1.0):
     def __str__(self):
         return str(self.pkt)
 
-    def pickled(self):
-        return b'PICKLED:' + pickle.dumps(self.pkt)
+    def json_packet(self):
+        return b'JSON:' + json.dumps(self.pkt).encode('utf-8')
 
 class Aircraft(DNFZ):
     '''an aircraft that flies in a circuit'''
@@ -459,7 +459,7 @@ def mavlink_packet(self, m):
         for a in self.aircraft:
             if not gen_settings.stop:
                 a.update(1.0)
-                self.pkt_queue.append(a.pickled())
+                self.pkt_queue.append(a.json_packet())
                 while len(self.pkt_queue) > len(self.aircraft)*2:
                     self.pkt_queue.pop(0)