Is VDL Mode 2 multi-frequency capability required?
Revision 5 of ARINC Specification 361 was recently ratified, and this includes details of multi-frequency autotune functionality. Although not a direct requirement of Regulation 29/2009, if ATN CPDLC were to be implemented without VDL-2 multi-frequency support, the overall system would become unusable, i.e. message delays would be unacceptable and not compliant with the DLS IR Performance requirements. One could imagine a system where there would be a number of aircraft without the multi-frequency capability, but these would add much complication to the overall system management when multi-frequency is employed on the ground. Multi-frequency functionality is expected to be available on the ground (operational) sometime in 2013-2014. This is according to the VDL-2 capacity analysis through simulations performed by EUROCONTROL, whose results are that multiple VDL-2 frequencies are required some 2 years after the forward-fit deadline.
