This project has received funding from the Clean Sky 2 Joint Undertaking (JU) under grant agreement No 945583. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and the Clean Sky 2 JU members other than the Union. The results, opinions, conclusions, etc. presented in this work are those of the author(s) only and do not necessarily represent the position of the JU; the JU is not responsible for any use made of the information contained herein. Prototype of the new Honeywell GPS-aided MEMS based navigation system (GPAHRS) has been validated through a large flight-test campaign performed under the Clean Sky 2 Large Passenger Aircraft (LPA) Platform 3 project. The campaign itself (more than 200 flight hours in total) was focused on the business jets (Dassault Falcon 900EX), commercial jets (Airbus A330), and regional aircrafts and various flight test scenarios. This paper provides an overview of the GPAHRS system itself, its integration within the Flight Test Bed (FTB) equipment, and most importantly, performance (in terms of accuracy and integrity) validation of results obtained during the campaign.