The High Ice Water Content (HIWC) hazard to aviation
Experimental nowcasting products for avoidance of HIWC conditions
Engaging with potential users
Product evaluation in an operational setting
Exercise goals
Large concentrations of small ice crystals can exist in areas
of convective clouds with low radar reflectivity
Ice crystals stick to warm metal surfaces in jet engine low
pressure compressor
Over 150 Ice Crystal Icing events confirmed to date (Event locations provided by M. Bravin, Boeing, 2015)
◦ Ice accretes; accumulated ice can
block flow into engine core or shed
into high pressure compressor or
combustor
◦ Result may be power surge, power
loss, engine damage
Aircraft data systems may
also be affected by ingest of
ice crystals into inlets ◦ Result may be errors in
temperature, air speed, and angle
of attack
Engine modification
Detection of ice crystals by pilots’ weather radar
Identification of HIWC areas with standard meteorological data sets ◦ Products to enable avoidance of hazard
◦ Development efforts underway by multiple research teams
Uses operationally available data as input
Applies fuzzy logic methodology to blend input data Apply expert knowledge to create rule-based behavior
Membership functions characterize the relationship of each variable to the possibility of HIWC conditions
Blend data with adjustable weighting factors
Provides a 3-dimensional estimate of HIWC potential 0: minimum interest, no HIWC likely
1: maximum interest, high likelihood of HIWC
Currently uncalibrated
*Research sponsored by U.S. FAA
Operationally available data
Blend via algorithms using fuzzy logic rules/ membership functions Gridded field of potential for HIWC conditions
Three field campaigns ◦ 23 flights based in Darwin,
Australia
◦ 16 flights based in Cayenne, French Guiana
◦ 10 flights based in Florida, US
IWC Measurements ◦ In situ Isokinetic Probe
◦ Cloud radar retrievals of IWC profiles
Machine Learning Technique for Algorithm Tuning ◦ Data set partitioned into
Training and Verification subsets
HIWC Potential
PoD-yes: 77.3%
Misses: 22.7%
PoD-no: 79.4%
False Alarm Rate: 20.6%
ALPHA v2.1 Performance Statistics
Experimental
ALPHA available
in real-time over
U.S. since 2016
Informal
feedback
solicited from
small set of
users
Currently no
mechanism to
obtain structured
feedback on
utility and
performance or
quantitative data
for verification
Joint effort with Australian Bureau of Meteorology
(BOM), NCAR, and U.S. Federal Aviation
Administration (FAA)
Provide experimental HIWC products to aviation
industry stakeholders for a discrete time period
Qantas
Virgin Australia
Solicit feedback on product performance and
utility during convective season
Evaluate and modify ALPHA as indicated by user
experience
HIWC Nowcasting Trial Exercise
ALPHA
implemented over
northern Australia
and maritime
continent
Initial trial during
monsoon
convective
season, Jan-Mar
2018; second trial
in 2019
Monitor
performance
based on airline
feedback
HIWC Nowcasting Trial Exercise
ALPHA Domain
Radar Data Available
HIWC Nowcasting Trial:
Organizational Structure and Responsibilities
NCAR • Regional ALPHA
development • Implementation
on BOM server • Scientific and
technical support • Evaluate and
incorporate feedback to improve algorithms
BOM • Provide input data
• ACCESS • HIMAWARI-8 • Radar
• Host server • Prepare and
distribute products
• Coordinate and analyze feedback
Airlines • Access product and
integrate with other meteorological products
• Monitor areas identified as HIWC
• Pilot education on characteristics of HIWC in flight
• Note suspected encounters with HIWC
• Provide feedback
ALPHA
Development
Installation
& Testing
Product
Trial:
Phase I
Post-trial
Workshop
ALPHA
Modification
Installation
& Testing
Product
Trial:
Phase II
Final
Report
HIWC Nowcasting Trial Exercise: Schedule
2017 May Dec 2018 Jan Mar
2018 Jul Dec 2019 Jan Mar
HIWC Nowcasting Trial: Expected Outcomes
Provide the BOM with an experimental HIWC nowcasting
capability.
Provide NCAR and FAA with feedback on ALPHA
performance in a region with frequent convection and ICI
events.
Provide information to be used for further improvements to
ALPHA
Inform FAA and BOM decision on feasibility of a fully
operational HIWC nowcasting product.
Progress the development of an international capability for
HIWC detection and prediction that may be required by ICAO
in the future.