diff --git a/examples/kiss_modem/KissModem.cpp b/examples/kiss_modem/KissModem.cpp
index 5e8b00d521..eeab1501d5 100644
--- a/examples/kiss_modem/KissModem.cpp
+++ b/examples/kiss_modem/KissModem.cpp
@@ -129,6 +129,8 @@ void KissModem::processFrame() {
         memcpy(_pending_tx, data, data_len);
         _pending_tx_len = data_len;
         _has_pending_tx = true;
+      } else if (_has_pending_tx) {
+        writeHardwareError(HW_ERR_TX_BUSY);
       }
       break;
 
@@ -257,6 +259,7 @@ void KissModem::processTx() {
           _tx_timer = millis();
           _tx_state = TX_DELAY;
         } else {
+          _tx_timer = millis();
           _tx_state = TX_WAIT_CLEAR;
         }
       }
@@ -273,19 +276,30 @@ void KissModem::processTx() {
           _tx_timer = millis();
           _tx_state = TX_SLOT_WAIT;
         }
+      } else if (millis() - _tx_timer >= _radio.getEstAirtimeFor(KISS_MAX_PACKET_SIZE) * KISS_TX_TIMEOUT_FACTOR) {
+        _tx_timer = millis();
+        _tx_state = TX_DELAY;
       }
       break;
 
     case TX_SLOT_WAIT:
       if (millis() - _tx_timer >= (uint32_t)_slottime * 10) {
+        _tx_timer = millis();
         _tx_state = TX_WAIT_CLEAR;
       }
       break;
 
     case TX_DELAY:
       if (millis() - _tx_timer >= (uint32_t)_txdelay * 10) {
-        _radio.startSendRaw(_pending_tx, _pending_tx_len);
-        _tx_state = TX_SENDING;
+        if (_radio.startSendRaw(_pending_tx, _pending_tx_len)) {
+          _tx_timer = millis();
+          _tx_state = TX_SENDING;
+        } else {
+          uint8_t result = 0x00;
+          writeHardwareFrame(HW_RESP_TX_DONE, &result, 1);
+          _has_pending_tx = false;
+          _tx_state = TX_IDLE;
+        }
       }
       break;
 
@@ -296,6 +310,12 @@ void KissModem::processTx() {
         writeHardwareFrame(HW_RESP_TX_DONE, &result, 1);
         _has_pending_tx = false;
         _tx_state = TX_IDLE;
+      } else if (millis() - _tx_timer >= _radio.getEstAirtimeFor(_pending_tx_len) * KISS_TX_TIMEOUT_FACTOR) {
+        _radio.onSendFinished();
+        uint8_t result = 0x00;
+        writeHardwareFrame(HW_RESP_TX_DONE, &result, 1);
+        _has_pending_tx = false;
+        _tx_state = TX_IDLE;
       }
       break;
   }
diff --git a/examples/kiss_modem/KissModem.h b/examples/kiss_modem/KissModem.h
index 60566add92..bbe99d6de4 100644
--- a/examples/kiss_modem/KissModem.h
+++ b/examples/kiss_modem/KissModem.h
@@ -26,6 +26,7 @@
 #define KISS_DEFAULT_TXDELAY     50
 #define KISS_DEFAULT_PERSISTENCE 63
 #define KISS_DEFAULT_SLOTTIME    10
+#define KISS_TX_TIMEOUT_FACTOR   3/2   // 1.5x estimated airtime
 
 #define HW_CMD_GET_IDENTITY      0x01
 #define HW_CMD_GET_RANDOM        0x02
@@ -71,6 +72,7 @@
 #define HW_ERR_MAC_FAILED        0x04
 #define HW_ERR_UNKNOWN_CMD       0x05
 #define HW_ERR_ENCRYPT_FAILED    0x06
+#define HW_ERR_TX_BUSY           0x07
 
 #define KISS_FIRMWARE_VERSION 1