Enhanced Virtual Block Control for Milan Malpensa Airport in low visibility

The Virtual Block Control concept makes use of virtual stop bar positions on a controller display and aims at reducing the size of control blocks that are used under low visibility conditions to achieve sufficient spacing between taxiing aircraft. The concept was evaluated in the past as part of a EUROCONTROL initiative in combination with different safety nets for minimum spacing, block boundary crossings and runway entry on the NARSIM Tower simulation platform of the National Aerospace Laboratory of the Netherlands, NLR (Figure 1). The airport chosen at the time was Rotterdam Airport (EHRD). While this airport proved to be ideal for demonstration and evaluation purposes, the simplicity of its layout did not allow drawing conclusions on achievable performance improvements in more complex environments [1]. Within the Single European Sky ATM Research Programme, Virtual Block Control was chosen as an operational concept for improving weather resilience at airports as part of the conceptual step towards time-based operations. Concept feasibility and expected performance were validated on the NARSIM Tower platform which realistically simulated a working environment for MilanMalpensa Airport (LIMC). This airport was chosen as its layout was very complex allowing for implementation of a much more mature concept of use as compared to the earlier evaluations. In its final set-up, the new system incorporated Virtual Block Control, alerting for unauthorized block boundary crossings, a Watch Dog alerting concept for monitoring aircraft that are supposed to hold position and a clearance limit administration for all controller positions in the simulation. Regarding feasibility of the concept, overall scores obtained presented a very positive picture of the operations with the new functionalities. Controllers easily accepted the new system functionality and were frequently missing these tools as helpful means to maintain situational awareness and safety of operations in the refe- ence situation that reflected currently applied operational procedures. Observations made in an Alenia Regional Aircraft flight simulator with a moving map display including virtual stop bar positions and alerting for block boundary crossings resulted in similar conclusions regarding operational feasibility aspects and operational improvements for the flight crew. By comparing results for different arrival capacities, statements about efficiency of operations could be made. The new system functionality allowed for working with up to 20% more traffic under low visibility conditions leading to clear efficiency gains. At higher capacity values of about 30% more traffic than in the current situation, the efficiency gains seemed to level out. Still better results were obtained for mental workload, teamwork aspects and situational awareness.