Anti-Ice and Rain - 757-300 Ice Detection System

An ice detecting sensor is installed on the nose of the airplane. The sensing element of the probe oscillates and the oscillation frequency of the probe changes with the thickness of the ice layer. When the sensor detects ice (0.5 mm), the amber ICING light illuminates and the EICAS advisory message ICE DET ON displays. When the sensor no longer detects ice, the ICING light extinguishes and the EICAS advisory message ICE DET OFF displays.

The system operates in an advisory capacity only. Flight Crew action is required to activate and de-active the Engine Anti-Ice and Wing Anti-Ice systems.

Internal probe heaters de-ice the probe after ice has been detected. The heaters are turned on for 7 seconds to melt the ice. Icing indications are displayed for 1 minute.

If the detector probe fails, the probe heaters are disabled and an ICE DETECTOR maintenance message appears on EICAS.

System electrical power comes from the Right Main AC bus.

EICAS