Improvements in tiltrotor performance can be reached with a reliable real-time monitoring of proprotor flapping angle. To overcome reliability and durability limitations due to the challenging operating environment, especially in terms of vibrations, the present topic relates to the provision of a contactless measurement system to be integrated in the proprotor assembly. It shall preferably be based on laser or vision sensor(s), and capable of communicating with the NGCTR avionic system and Flight Test Instrumentation providing actual flap motion. This includes also support to flight test activity. Please refer to the full and formal topic descriptions published in this call.