Icing is one of aviation’s major hazards and one that has been a causal factor in numerous accidents. Between 1982 and 2000, it was instrumental in more than 550 accidents that resulted in over 800 fatalities. While the lift- and controllability degrading effects of ice accretion on flying and control surfaces are well known, the ability to detect icing as it occurs has been a more difficult issue.
In many icing events the flight crew were unaware that they were flying in the atmospheric temperature and moisture conditions conducive to ice formation until it was too late. There can often be a considerable time lag between the onset of icing conditions and the pilot becoming aware of them through a degradation of performance or handling.
A clear answer is to detect ice formation long before it becomes apparent to the flight crew, allowing them to take appropriate actions such as activating ice protection systems or finding different meteorological conditions before the ice accretion becomes critical.
Safe Flight Instrument (Booth 1416) of White Plains, N.Y., has developed an icing conditions detector (ICD) system using a combination of optical detection and a shielded temperature probe. The optical system uses an LED, a prism and an infrared sensor to detect the presence of moisture in the air. It uses dynamic biasing to adapt to ambient light conditions and to reject strong ambient signals, such as those coming from the sun. Combining moisture detection with accurate temperature information allows the system to detect when icing conditions are encountered, and an alert is issued to the pilot.
Safe Flight has developed and tested the ICD at its facility, with additional tests being conducted at the National Research Center in Ottawa, Canada. These trials have shown the system’s ability to respond with an alert within a few seconds of entering icing conditions. A form-fit has been developed to take into account airflow, drag and installation considerations. Safe Flight expects a deliverable ICD to weigh between 0.5 and 0.8 pounds.
