diff --git a/libraries/SITL/SIM_FlightAxis.cpp b/libraries/SITL/SIM_FlightAxis.cpp
index 0e1a947449..8530666ae0 100644
--- a/libraries/SITL/SIM_FlightAxis.cpp
+++ b/libraries/SITL/SIM_FlightAxis.cpp
@@ -134,9 +134,13 @@ FlightAxis::FlightAxis(const char *frame_str) :
     }
 
     const char *colon = strchr(frame_str, ':');
+    const char *env = getenv("REALFLIGHT_IPADDR");
     if (colon) {
         controller_ip = colon+1;
     }
+    else if (env) {
+        controller_ip = env;
+    }
     for (uint8_t i=0; i<ARRAY_SIZE(sim_defaults); i++) {
         AP_Param::set_default_by_name(sim_defaults[i].name, sim_defaults[i].value);
         if (sim_defaults[i].save) {