Trust is a concept that cannot be easily measured. Further, trust is domain-specific. Trust is a foundational aspect of safe flight operations in the National Airspace System, and while there has been much attention to trust in teams and trust in automation, there appears to be a gap in knowledge of a pilot’s trust in air traffic controllers. The purpose of this study was to develop and validate the Trust in Air Traffic Controllers (T-ATC) scale, a summative scale to measure a pilot’s trust in air traffic controllers. This study followed a three-step methodology. In steps one and two, words were generated using an online Delphi process. In step three, the proposed instrument was set in a scenario-based test using over 200 pilots as participants. The data were subjected to Principal Components Analysis (PCA) which indicated a single component explaining 69.06% of the total variance. A Cronbach’s alpha of 0.90 showed the scale to have high internal consistency, and a Guttman split-half test result of 0.91 indicated the scale had high reliability. Safety within the National Airspace System requires a high degree of cooperation between system actors facilitated through trust in system components. In a system reliant upon trust, there is little knowledge of trust between pilots and controllers and therefore, no foundation for understanding and addressing trust dynamics. The T-ATC scale can now be used by aviation researchers to close the gap in knowledge regarding a pilot’s trust in controllers.