Communication Latency and Loss for Integrated IFR-RPAS Movements in the TMA

In recent years, innovative technology emerged enabling unmanned flight and putting a strain on airspace as a resource. It is expected that the number of remotely piloted aircraft (RPA) will increase significantly in the near future. In 2021 Royal NLR performed real-time simulations for the SESAR Exploratory Research Project INVIRCAT addressing some of the consequences of that development. The INVIRCAT project investigates the safe and efficient integration of the movements of RPAs under instrument flight rules into current-day operations at and around smaller but significant airports with a variable mix of traffic. NLR activities focused on Rotterdam The Hague Airport (ICAO: EHRD).The NLR simulation set-up included a high-fidelity tower and approach simulation environment (NARSIM Tower and NARSIM Radar) and a connected simulation platform for a generic Remotely Piloted Aircraft System (RPAS) Ground Control Station facility (called Multi Unmanned Aircraft Supervision Testbed, MUST). Experienced former air traffic controllers guided all aircraft in the traffic mix including the drone traffic. A military pilot was responsible for control of the RPAS and so-called pseudo-pilots controlled the remaining visual (VFR) and instrument (IFR) traffic in the Terminal Manoeuvring Area (TMA) and at the airport.The present paper focusses on the results of the real-time simulations that are related to latency in radio communication between RPAS pilot and Air Traffic Control (ATC) as well as procedural issues regarding loss of voice communication.Latency was suspected to have an immediate impact on the work of air traffic controllers as it would slow down both pilot readbacks and pilot flight control responses to ATC instructions. Different radio delay parameters were tested in abovementioned environment and controller and pilot reactions were studied.Loss of voice communication was also assessed in all flight phases applicable to approach and departure operations in the TMA. Both pilot and ATC feedback on the procedures was collected leading to surprising results that may trigger a re-evaluation of our notions of voice communication loss with remote pilots. One of the most notable results was that both pilots and controllers were adamant that the IFR RPAS should follow the same procedures defined for manned IFR traffic.