diff --git a/libraries/AP_ADSB/AP_ADSB.cpp b/libraries/AP_ADSB/AP_ADSB.cpp
index 1e773fa567..4d8974c924 100644
--- a/libraries/AP_ADSB/AP_ADSB.cpp
+++ b/libraries/AP_ADSB/AP_ADSB.cpp
@@ -172,7 +172,7 @@ const AP_Param::GroupInfo AP_ADSB::var_info[] = {
     // @Param: OPTIONS
     // @DisplayName: ADS-B Options
     // @Description: Options for emergency failsafe codes and device capabilities
-    // @Bitmask: 0:Ping200X Send GPS,1:Squawk 7400 on RC failsafe,2:Squawk 7400 on GCS failsafe,3:Sagetech MXS use External Config
+    // @Bitmask: 0:Ping200X Send GPS,1:Squawk 7400 on RC failsafe,2:Squawk 7400 on GCS failsafe,3:Sagetech MXS use External Config,4:Transmit in traditional Mode 3A/C only and inhibit Mode-S and ES (ADSB) transmissions
     // @User: Advanced
     AP_GROUPINFO("OPTIONS",  15, AP_ADSB, _options, 0),
 
diff --git a/libraries/AP_ADSB/AP_ADSB.h b/libraries/AP_ADSB/AP_ADSB.h
index 45cce0f328..a66b57202c 100644
--- a/libraries/AP_ADSB/AP_ADSB.h
+++ b/libraries/AP_ADSB/AP_ADSB.h
@@ -78,6 +78,7 @@ public:
         Squawk_7400_FS_RC               = (1<<1),
         Squawk_7400_FS_GCS              = (1<<2),
         SagteTech_MXS_External_Config   = (1<<3),
+        Mode3_Only                      = (1<<4),
     };
 
     // for holding parameters
diff --git a/libraries/AP_ADSB/AP_ADSB_Sagetech_MXS.cpp b/libraries/AP_ADSB/AP_ADSB_Sagetech_MXS.cpp
index 39fd88810b..ec4e49b7d4 100644
--- a/libraries/AP_ADSB/AP_ADSB_Sagetech_MXS.cpp
+++ b/libraries/AP_ADSB/AP_ADSB_Sagetech_MXS.cpp
@@ -150,7 +150,7 @@ void AP_ADSB_Sagetech_MXS::update()
         last.operating_rf_select = _frontend.out_state.cfg.rfSelect;
         last.modeAEnabled = _frontend.out_state.ctrl.modeAEnabled;
         last.modeCEnabled = _frontend.out_state.ctrl.modeCEnabled;
-        last.modeSEnabled = _frontend.out_state.ctrl.modeSEnabled;
+        last.modeSEnabled = (_frontend._options & uint32_t(AP_ADSB::AdsbOption::Mode3_Only)) ? 0 : _frontend.out_state.ctrl.modeSEnabled;
 
         last.operating_alt = _frontend._my_loc.alt;
         last.packet_Operating_ms = now_ms;
diff --git a/libraries/AP_ADSB/AP_ADSB_uAvionix_UCP.cpp b/libraries/AP_ADSB/AP_ADSB_uAvionix_UCP.cpp
index 0f92293c51..cb9f6cfc45 100644
--- a/libraries/AP_ADSB/AP_ADSB_uAvionix_UCP.cpp
+++ b/libraries/AP_ADSB/AP_ADSB_uAvionix_UCP.cpp
@@ -411,8 +411,8 @@ void AP_ADSB_uAvionix_UCP::send_Transponder_Control()
     _frontend.out_state.ctrl.identActive = false; // only send identButtonActive once per request
     msg.modeAEnabled = _frontend.out_state.ctrl.modeAEnabled;
     msg.modeCEnabled = _frontend.out_state.ctrl.modeCEnabled;
-    msg.modeSEnabled = _frontend.out_state.ctrl.modeSEnabled;
-    msg.es1090TxEnabled = _frontend.out_state.ctrl.es1090TxEnabled;
+    msg.modeSEnabled = (_frontend._options & uint32_t(AP_ADSB::AdsbOption::Mode3_Only)) ? 0 : _frontend.out_state.ctrl.modeSEnabled;
+    msg.es1090TxEnabled = (_frontend._options & uint32_t(AP_ADSB::AdsbOption::Mode3_Only)) ? 0 : _frontend.out_state.ctrl.es1090TxEnabled;
 
     // if enabled via param ADSB_OPTIONS, use squawk 7400 while in any Loss-Comms related failsafe
     // https://www.faa.gov/documentLibrary/media/Notice/N_JO_7110.724_5-2-9_UAS_Lost_Link_2.pdf