CAS 7.1 software installed by Jan 1st, 2016 for the B727= U.S. Airspace is not required to have TCAS=7.1 until year 2020. Cost for software upgrade to=7.1 TCAS is $60,511 (due to age and Mod status of 8727 TCAS unit, we=have to upgrade our box before 7.1 software could be installed). We have 7.1 TCAS alrea