These brightly colored tags, often red and bearing the stark warning, serve a critical safety function in aviation. They act as reminders to ground crews to remove temporary safety devices installed on aircraft prior to flight. These devices might include covers protecting pitot tubes (which measure airspeed), engine intakes, or control surfaces. Leaving these safeguards in place during flight could have catastrophic consequences, impacting aircraft performance and control.
Their presence ensures the aircraft is ready for flight, highlighting the importance of meticulous pre-flight checks. This simple yet effective system prevents potentially disastrous oversights, contributing significantly to aviation safety. The practice originated in the early days of aviation as aircraft systems became more complex and the need for temporary safety devices increased.