4.2.1 Number and size of aerodromes in multiple mode of operation

The number and size of aerodromes to be combined in multiple mode of operation need to be carefully assessed. Furthermore, not only the number of aerodromes, but also the selection of the appropriate combination of aerodromes considering operational aspects (such as traffic levels and complexity, type of ATS provided on each aerodrome (ATC or AFIS), approach control service provision, meteorological conditions across the aerodromes, geographical locations and the aerodromes’ surrounding topography/terrain, runway orientations, etc.) should be thoroughly considered when providing ATS via the multiple mode of operation. Also, a suitable level of equipage to support the operations should be determined. The local safety assessment, taking traffic density, complexity and other local factors into account, should determine the suitable number and combination of simultaneous aerodromes (which may vary over time, depending on e.g. traffic distribution, weather, etc.). The results of the validation exercises performed so far (continued research is ongoing within SESAR 2020, see Section 4.2.6) in the framework of the SESAR JU programme ([23], [33]) show that the multiple mode of operation can be applied for the simultaneous provision of ATS to two low-density aerodromes (as described by SESAR) by a single ATCO/AFISO. The basic features (as described by SESAR, see Appendix 4) are deemed to be adequate for ATC service and AFIS provision at these low-density aerodromes, even though the level and flexibility of service provision can be improved through the use of advanced features (as described by SESAR, see Appendix 4). The required equipage would be dependent on e.g. traffic level and complexity (including mixture of aircraft and vehicles) as well as aerodrome layout and its complexity, rather than the provision of ATS to multiple aerodromes (as opposed to a single aerodrome). Similar to this, it can be noted that the SESAR validation results have revealed that the total traffic level and complexity generally have a greater impact on ATCO/AFISO workload than the number of aerodromes to which services are being provided.