diff --git a/drone_controller/mission_manager.py b/drone_controller/mission_manager.py
index bd6b327..c5a821e 100644
--- a/drone_controller/mission_manager.py
+++ b/drone_controller/mission_manager.py
@@ -677,6 +677,7 @@ class MissionManager:
         """
         # ---- 不发送任何 SETPOINT — 控制权已让渡 ----
 
+        global lost_elapsed
         tracking_elapsed = time.time() - self.tracking_start_time
 
         # ---- 兜底超时 ----