Experiences in Data Analysis of a GBAS Approach Test

This paper moves from a set of data collected during a campaign recently carried out at Milan Linate airport (Italy) by the Italian Company for Air Navigation Services (ENAV S.p.A.) in cooperation with several avionic instrumentation manufacturers and engineering firms. Tests were aimed to investigate the performances during the approach phase of GPS equipment accommodated on-board and aided by a Ground-Based Augmentation System (GBAS) transmitting section located close to the runway. Differential corrections were transmitted to the aircraft via a VHF link, and have been recorded at a monitor station as well. The comparative analysis of data gathered on-board the aircraft and collected at the ground stations helps in evaluating and assessing the system behaviour. Additionally, the information collected have been used to tune a dynamic model of a plane performing the approach phase, implemented in MATLAB, and specially fitted to the aircraft (CESSNA Citation II) used during the tests. First of all, the availability of data from this campaign allows making a realistic assessment of the sensor noise associated with the GBAS approach to be included in numerical simulations. Moreover, the set of data gathered at 10 Hz rate for a large number of approaches carried out for testing purposes, together with Standard (Instrument) Arrival Route (STAR) related to Linate airport and followed during the campaign, are quite useful in order to improve the dynamic model of the Citation II during the landing phase. By means of this well tuned model it is possible to assess the performances of GBAS for Linate and, with a certain confidence, for other airports, and to compare them with traditional Instrumental Landing System (ILS) aided approaches.