PX4 Autopilot versions 1.12.x through 1.15.x contain a protection mechanism failure in the "Re-arm Grace Period" logic. The system incorrectly applies the in-air emergency re-arm logic to ground scenarios. If a pilot switches to Manual mode and re-arms within 5 seconds (default configuration) of an automatic landing, the system bypasses all pre-flight safety checks, including the throttle threshold check. This allows for an immediate high-thrust takeoff if the throttle stick is raised, leading to loss of control.