HASTAC - High Stability Altimeter System for Air Data Computers
Overview
Background & policy context:
The project responded to the challenge of ensuring that, irrespective of the growth of air traffic, air transportation would be safer. HASTAC contributed to one of the major challenges identified on the Strategic Research Agenda for European aeronautics. Referring to incidents such as, 11 September, the SAS plane in Milan Airport and the in-air crash at Bodensee, the European avionics industry focused on development programmes to improve this type of safety.
HASTAC contributed to improving safety in different flight situations, such as:
- On-board technologies for prevention of controlled flight into terrain;
- Technologies enabling a full and permanent automatic approach and landing in all weather;
- On-board technologies for in-flight and on-ground collision avoidance novel concepts;
- Techniques enabling the development of improved aviation safety metrics.
Objectives:
The main project strategic objective was to increase the safety in all in-flight situations, particularly in low visibility situations, by improving the transducers used in Air Data Computers (ADC) for aircraft applications. The results proved relevant to flying on autopilot in the reduced vertical separation minima of 1 000ft, as well as to demanding manual flying situations in darkness and low visibility. In transponder applications, the project gave a significantly increased reliability in altitude information for manual and automated Air Traffic Control systems. Aircraft Traffic Collision Avoidance Systems would also benefit from more accurate and reliable altitude information, which would allow the automated avoidance instructions to be more accurate and effective.
The project developed a new generation of air data computers (ADC), suitable for fixed wing and rotary wing applications, which would significantly improve altitude accuracy capabilities over those available today. Aircraft flight-testing performed in the project demonstrated the effectiveness of the performance improvement. A new generation of transducers with a new microsensor (absolute pressure sensing element) as the key component, would also be available for other application areas, such as transponders.
Methodology:
The work was divided into five Work Packages.
- Work Package 1: Sensing element: Development of an absolute pressure-sensing element in silicon (MEMS) with a minimal number of unidentified error sources featuring excellent long-term stability and high repeatability in aerospace applications.
- Work Package 2: Pressure sensor package: Development of a new hermetic pressure sensor package that minimised transfer of unwanted forces to the silicon-sensing element developed in Work Package 1.
- Work Package 3: Transducer: Development of an optimised digital altimeter transducer based on the packaged sensor with a long-term stability specification better than 0.01%FS/year.
- Work Package 4: Air-Data Computer Unit: Development of a new digital air data computer unit that utilised the improved accuracy in altimeter barometric measurements from the developed transducer.
- Work Package 5: Aircraft flight test: Demonstration of the improved safety performance by real helicopter flight tests.
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