Long-term monitoring of barometric altitude measurement performance using the example of a research aircraft

Abstract The barometric flight altitude is the decisive variable for the vertical separation of aircraft in the airspace. At present, no aircraft operator is able to independently monitor the proper function of barometric altimetry in flight. In this paper, a method is presented for long-term monitoring of barometric altimetry system performance only by means of flight data and model output data from a numerical weather prediction model. This method enables aircraft operators to independently monitor barometric altimetry system performance of their aircraft fleet. Aberrant aircraft can be identified earlier and can be taken out of service for inspection measures more predictable, or inspected as part of already planned maintenance measures. Already existing flight data from DLR’s research aircraft Airbus A320-232 ATRA from 2014 to 2020 were used to determine the long-term behavior of the barometric altitude measurement performance using this method. During two of the flights under consideration, the aircraft was equipped with a trailing cone system, which is currently considered the most accurate way for measuring ambient pressure airborne. Hence, these flights were used as a reference. The summary of the implementation, evaluation, and main results is presented in this paper, starting with a brief introduction to numerical weather prediction models and their model output data. Details on the air data system and position measurement of the research aircraft are addressed as well as prerequisites regarding selection of parameters. Both reference and distance flights are described during which the analyzed flight data were gathered. Data pre-processing and evaluation are explained comprehensively. Finally, obtained results and findings are assessed and discussed with regard to the applicability of the method and future research work. In summary, application of the presented method to a research aircraft has shown good agreement compared to an established method such as the trailing cone system.