MIT Lincoln Laboratory (MIT/LL) is supporting the FAA-sponsored effort to specify Computer Human Interface (CHI) requirements for the En Route Air Traffic Management Decision Support Tools (ERATMDST) program. The ERATMDST CHI specification is the FAA's vehicle to ensure an operationally suitable user interface is provided for the DSTs (such as conflict probe) to support free flight. The initial draft of the ERATMDST CHI requirements was published in September 1998 and defines an initial CHI which incorporates elements of the NASA CTAS and the MITRE URET prototypes, an Operational Display and Input Development (ODID) display philosophy, and an outline of the end-state CHI. The information will be presented with a consistent, usable look and feel modeled on the advanced human-centered CHI developed by Eurocontrol. This paper describes a CHI Requirements Engineering Model (CREM) and presents preliminary test results of ODID-like display elements in the ERATMDST CHI with controller-in- the-loop simulations presented in terms of workload and response times.