Nomenclature ADS-B = Automatic Dependent Surveillance-Broadcast AGD = ADS-B Guidance Display

NASA’s first Air Traffic Management (ATM) Technology Demonstration (ATD-1) was created to facilitate the transition of the most mature air traffic management technologies from the laboratory to the airspace. One of the selected technologies is Interval Manage-ment (IM), which uses automation on board the aircraft to compute speeds that pilots can fly to achieve or maintain precise in-trail spacing behind a preceding aircraft. Since ATD-1 focuses on a near-term environment, the IM prototype used in the ATD-1 flight demonstration will require the use of voice communications to issue IM clearances to the pilots. Retrofit IM displays will be used to enable pilots to enter information into the IM avionics and monitor the IM operation. These displays could consist of an interface used to enter data from an IM clearance and an auxiliary display that presents critical information in the primary field-of-view. A human-in-the-loop experiment was conducted to examine the usability and acceptability of retrofit IM displays. This experiment investigated both numerical and graphical primary field-of-view displays while conducting nominal IM op-erations. The results provide information that can be used to guide the development o