RTCA is accepting comments on planned revisions two NextGen-related standards documents that will form the basis of related FAA TSOs.
The first is RTCA Document DO-282A, Minimum Operational Performance Standards for Universal Access Transceiver (UAT) Automatic Dependent Surveillance Broadcast (ADS-B), which will become the Minimum Performance Standard (MPS) for the proposed revised TSO-C154c.
The second is RTCA Document DC-260A, Minimum Operational Performance Standards for 1090 MHz Extended Squitter Automatic Dependent
Surveillance - Broadcast (ADS-B) and Traffic Information Service - Broadcast (TIS-B), which will be the foundation of TSO-166b.
Comments are due to RTCA by Sept. 30. For instructions on how to comment, see this notice (.pdf) for draft DO-282B, and this notice (.pdf) for draft DO-260B. More information on the subsequent TSOs is available here.