Starting December 1st 2015 if you fly a Large Aircraft into EU Airspace, you need to be equipped with Version 7.1 of Traffic Alert and Collision Avoidance System.
The Federal Aviation Administration (FAA) authorizes, but does not mandate TCAS II Version 7.1 software [yet] for use in the National Airspace System (NAS). Version 7.1 is defined by FAA TSO-C119c. With introduction of TCAS II Version 7.1, the FAA now permits three versions of TCAS II in US airspace; V6.04a, V7.0 and V7.1 .
More information about TCAS II can be found in the FAA’s Introduction to TCAS II V7.1 pamphlet by clicking this link: FAA TCAS-II V7.1 Booklet
Operators of aircraft with TCAS II installed and also conducting international flight operations, need to be aware that ICAO Annex 10 requires Version 7.1 software on new aircraft by January 1, 2014, and for existing aircraft by January 1, 2017. Operators should note that an EU Implementing Rule sets an earlier equipage requirement than those published in ICAO Annex 10. The EU mandate is applicable in EU airspace as of March 1, 2012 to all aircraft above 5,700 kg (12,500 lbs) Maximum Take-off Mass or authorized to carry more than 19 passengers. An extended deadline, December 1, 2015, is granted to aircraft with an individual certificate of airworthiness issued before March 1, 2012 and equipped with version 7.0.
The EU Implementing Rule also applies to aircraft that voluntarily equip with TCAS II. The EU Implementing Rule maybe viewed at the following link: EU TCAS II Version 7.1 Implementing Rule
Almost all large aircraft in the industry are already operating version 7.0, since its part of RVSM qualification. Going to Version 7.1 in most cases is a simple software upgrade with quick turn time.