Background
National Transportation Safety Board records indicate that in-flight icing causes more than 25 accidents annually, with over half of these resulting in fatalities and damaged aircraft. The cost of injuries, fatalities and aircraft damage is estimated to be $100M annually.
Current Icing Potential (CIP) depiction is for 9000 ft MSL, 1500UTC, 16 Feb 2005, as available today. Scale is uncalibrated likelihood, from 0 (no icing) to 100 (certain icing). No severity is depicted on this operational product (click on image to enlarge).
The RAL In-Flight Icing Program, under the leadership of M. Politovich, addresses this problem by producing improved operationally -available, high-resolution, accurate diagnoses and forecasts of aircraft icing conditions.
The Icing Program takes an end-to-end approach beginning with basic research, moving to the development of new products, and ending with operational implementation and development of user display packages. Most of this work is funded by the FAA's Aviation Weather Research Program through the InFlight Icing Product Development Team (IFIPDT). Development of diagnosis and forecast algorithms is led by B. Bernstein and G. Cunning, with major contributions from F. McDonough, C. Wolff and S.Mueller. The group has created a Current Icing Potential (CIP) algorithm that combines numerical weather model output with surface weather observations, satellite imagery, NEXRAD radar information, lightning data and pilot reports of icing using fuzzy logic techniques to produce a final output of icing potential. The methodology is based on basic cloud physics principles as well as forecaster experience. CIP has been thoroughly verified by the FAA’s Quality Assessment Product Development Team as part of the Aviation Weather Technology Transfer process and is run operationally by the National Weather Service. A forecast version of the algorithm (FIP) which uses only model input, and versions of the current and forecast algorithms for Alaska(CIP-AK and FIP-AK) are in various stages of operational readiness.
Current Activities
Proposed upgrade to CIP (click on image to enlarge). This is the same flight level and time shown in graphic above, but depicts icing severity for areas with greater than 20% probability of encountering icing conditions.
Research is essential if continued improvements in in-flight icing diagnosis and forecasting are to be made. To that end, the team is focused on improving the MM5, RUC and WRF numerical weather prediction models. G. Thompson, P. Field, B. Hall and R. Rasmussen have greatly improved the microphysical parameterizations in these models to provide better forecasts of potentially hazardous icing conditions.
Additional capabilities of satellites, radars and in situ sensors are being examined for their suitability for CIP within the IFIPDT. This work leverages funding from NASA’s Advanced Satellite Aviation-weather Products (ASAP) program, NASA’s Icing Remote Sensing System (NIRSS) development, and the NASA/AIRDAT TAMDAR program. ASAP research, led by J. Haggerty and D. Johnson, suggests great potential for further improvements in icing detection via satellite-based cloud analyses. Additional work with polar-orbiting satellite data by M. Deeter shows promise in quantifying liquid water over land surfaces. Through NIRSS and J.Vivekanandan and D. Serke’s work with NSF’s SPolKa dual-wavelength radar system, techniques for combining radar information with radiometers, satellites, or numerical weather model information has shown promise in detecting icing conditions in airport terminal areas. E. Brandes and K. Ikeda have been working on fuzzy-logic techniques for identifying freezing drizzle regions with NEXRAD data, which could have considerable significance if the FAA begins to certify aircraft for flight into those conditions. Quality assessment of TAMDAR icing data and its effect on CIP output are being studied by S. Landolt and J. Braid.
Although CIP is run operationally on ADDS by the NWS, its use is restricted because it does not depict severity or true probability. In order to increase use of the product both within FAA systems and by end-users, the algorithm must be upgraded to include severity and probability. A display concept that is more readily understood by users must also be developed. Work is underway at RAL in both areas and a number of upgrades will be implemented in 2006. Lifting of user restrictions will allow for the dissemination of the gridded output to a variety of display systems (e.g., cockpit weather and electronic flight bag displays) for direct use by aviation end-users.
Results
An initial study using NASA’s advanced satellite products to further improve the severity product was very encouraging in identifying areas of hazardous icing. Additionally, freezing drizzle detection using NEXRAD data looks very feasible, and RAL scientists are now in the process of determining where and how to implement the detection algorithm. Microphysical parameterizations are continually being upgraded and sent to NOAA’s Earth Systems Research Laboratory for implementation into the RUC model; these have made noticeable improvements in cloud condensate and precipitation forecasts. RAL also will prepare recommendations to the FAA and NWS concerning the benefits to the icing community of continued support of TAMDAR data acquisition.
From this work, RAL has learned that early interaction with regulatory agencies, documentation (Concept of Use and Operations) writers, and end-users is essential to ensure that the product will satisfy these groups as well as be technically correct. RAL is working with the FAA and support groups to ensure that the upgraded CIP either conforms to existing regulations, or that regulations are re-directed to fit the intended use of the CIP. RAL has also been very cognizant of the value of collaborations with universities and other laboratories to ensure “state-of-the-art” research
Recent Accomplishments
RAL is nearly finished with the technical development of the CIP severity/probability upgrade. Staff have also met with the AWTT Applied Science Group, FAA Flight Standards, and led an AWTT Public User Meeting to align the research and development effort with technical and regulatory requirements and issues. The next steps are verification of the new algorithm and code delivery to the Aviation Weather Center for installation and testing in preparation for an AWTT board decision in August 2006. These are lengthy but necessary steps in the technology transfer process and should proceed without delay.
Contact Information
Marcia Politovich — ph: 303.497.8449 | fx: 8401 | marcia@ucar.edu