NATS warning light 4

https://wiki-nest.win/index.php/Understanding_the_Nissan_Ignition_ON_Light_and_the_Car_with_Key_Symbol

The NATS warning light glows amber on the instrument panel when the aircraft's nacelle anti-ice system detects a fault or is improperly configured, alerting pilots before ice buildup compromises engine performance. It's a critical piece of cockpit awareness in icing conditions.