Commercial aircraft have been experiencing in-service events while flying in the vicinity of deep convective clouds since at least the early 1990's. Heated probes and engines are the areas of air-craft most prone to mixed phase and glaciated icing threat.
In 2004, the Engine Harmonisation Working Group (EHWG) was established to look at the effects of supercooled large droplets and glaciated and mixed phase icing conditions on engines. This working group established that this suspected engine icing phenomenon was present in both commuter and large transport category aircraft, and in all types/manufacturers of engine. It proposed a draft of regulation to FAA/EASA in 2009.
The corresponding regulation (Appendix O and D/P for FAR25/33 and CS25/CS-E) has been proposed for comments to industry (FAA NPRM 10-10 in June 2010, EASA NPA 2011-03 CS25 & 2011-04 CS-E in March 2011) and could be applicable by 2013.
In anticipation of regulation changes regarding mixed phase and glaciated icing conditions, the HAIC project will provide the necessary Acceptable Means of Compliance (numerical and test capabilities) and appropriate ice particle detection/awareness technologies to the European aeronautical industry for use on-board commercial aircraft in order to enhance safety when an aircraft is flying in such weather conditions.
HAIC will achieve high Technology Readiness Level (TRL6) for technologies (radar, detector) and capabilities (numerical models and tools, test facilities) developed as part of the project.
HAIC will also develop international cooperation and collaboration thanks to the involvement of key international organisations and companies as partners of the project or through the HAIC Advisory Board.
Finally, HAIC will complement the work performed by part of existing international projects and working groups, notably EASA-HighIWC, HIWC, Engine Icing Working Group and Ice Crystals Consortium, and pave the way towards the ACARE 2020 and Flight Path 2050 safety objectives.
The results of this work will provide:
- A characterisation of the microphysical properties of core or near-core regions of deep convective clouds based on a unique flight test dataset in deep oceanic convective storms.
- A set of experimental and numerical capabilities as Acceptable Means of Compliance (AMC) for the qualification and certification of future aircraft products (mainly probes and engines).
- Four complementary upgraded European icing test facilities with improved representativeness of simulated mixed phase and glaciated icing conditions and covering the whole flight and icing envelope (Low speed / High speed ; Sea level / Altitude).
- A unique numerical model for ice particle trajectory, impingement and accretion and mature research and industrial simulation tools to support pre-design, design and certification of equipments and systems (mainly engine and probes).
- A set of awareness and detection technologies to be fitted on aircraft and able to alert the flight crew when an aircraft is flying in such weather conditions.
- A pre-operational space-borne remote detection and nowcasting application of glaciated icing conditions based on imagery of geostationary MSG-SEVIRI satellite observations, validated with space-borne active and passive cloud observations from LEO and GEO missions and integrated into a pre-operational application for detection of Rapidly Developing Thunderstorm (RDT).
- An upgraded on-board weather radar (TRL6), based on current state-of-the-art X-band airborne weather radar equipment, to raise awareness to the flight crew of the encounter of glaciated icing conditions and ultimately to adapt well in advance the flight path to avoid such weather conditions.
- Two to four mixed phase and glaciated icing conditions detectors, depending on selection performed as part of the project, to alert the crew of flight in these particular icing conditions.
- An assessment of the relevance of the proposed mixed phase and glaciated icing environment and a set of recommendations to regulatory bodies (EASA/FAA) in light of the atmosphere characterization performed as part of the project.
Detecting high-altitude ice
An EU team is developing systems for detecting atmospheric conditions that cause aircraft icing. Work includes the selection of suitable probes, instruments and detection systems, plus their installation on aircraft for flight testing.
High-altitude icing is a serious threat to aviation safety, and especially affects engines. Systems able to detect and help aircraft avoid the dangerous atmospheric conditions will help improve safety.
Providing such systems is the EU-funded http://www.haic.eu (HAIC) (High altitude ice crystals) project. The exceptionally large consortium includes 34 European partners plus 5 from Australia, Canada and the United States. Main goals are to provide ice particle detection systems for enhanced aircraft safety, and to help the industry comply with anticipated new regulations.
The group has addressed 18 technical objectives concerning development of suitable systems. The partnership runs for four years from mid-2012 to mid-2016.
Second-year work involved selection of the most sophisticated probes for the first international field campaign, which were later installed on a research aircraft. Instruments supporting calibration of the test facilities were also selected and evaluated.
The first field campaign was conducted successfully in early 2014, and utilised the MET-FR RDT device for detecting thunderstorm convection. Analysis of all campaign data is on schedule.
Researchers assessed the project's capability to judge icing conditions using satellite data. Feasibility testing was also conducted on HAIC's detection systems and weather radar. Five of eight candidate technologies were selected for flight testing.
The team developed devices able to create ice crystals with specific sizes and other properties, to be used for testing. A calibration methodology was also created and shared with the international community. Finally, the group has completed laboratory testing of ice crystal trajectories and related phenomena, data from which led to the creation of preliminary mathematical models.
HAIC is producing a thorough understanding of icing conditions, to be incorporated into effective aviation warning systems. The expected result is improved aircraft safety, with a bonus of commercial possibilities for European business.