NASA has teamed with the FAA, DoD, industry, and academia for research into the remote detection and measurement
of atmospheric conditions leading to aircraft icing hazards. The ultimate goal of this effort is to provide pilots,
controllers, and dispatchers sufficient information to allow aircraft to avoid or minimize their exposure to the hazards of
in-flight icing. Since the hazard of in-flight icing is the outcome of aircraft flight through clouds containing supercooled
liquid water and strongly influenced by the aircraft's speed and configuration and by the length of exposure, the hazard
can't be directly detected, but must be inferred based upon the measurement of conducive atmospheric conditions.
Therefore, icing hazard detection is accomplished through the detection and measurement of liquid water in regions of
measured sub-freezing air temperatures. The icing environment is currently remotely measured from the ground with a
system fusing radar, lidar, and multi-frequency microwave radiometer sensors. Based upon expected ice accretion
severity for the measured environment, a resultant aircraft hazard is then calculated. Because of the power, size, weight,
and view angle constraints of airborne platforms, the current ground-based solution is not applicable for flight. Two
current airborne concepts are the use of either multi-frequency radiometers or multi-frequency radar. Both ground-based
and airborne solutions are required for the future since ground-based systems can provide hazard detection for all aircraft
in airport terminal regions while airborne systems will be needed to provide equipped aircraft with flight path coverage
between terminal regions.