Multiple applications for a trajectory conformance monitoring alarm

• A new alarm can alert controllers to an aircraft deviating from its assigned trajectory prior to loss of separation. • We used an alarm design framework to develop a new trajectory conformance alarm to monitor aircraft in the terminal environment. • The trajectory conformance alarm indicates an aircraft that is deviating from an assigned ground track or altitude. • The alarm design framework encouraged air traffic controllers to develop innovative applications for a new alarm that may enhance safety and efficiency. • Additional applications include aircraft flying an incorrect procedure, deviating into restricted airspace, or violating altitude restrictions. Incorporating a trajectory conformance alarm for assigned procedures can alert air traffic controllers prior to loss of separation. Study 1 : We hypothesized that a query of the FAA’s Mandatory Occurrence Report (MOR) database would find trajectory deviations causing loss of separation. Study 2 : We hypothesized that controllers would judge a trajectory conformance alarm created with the Alarm Design Framework as an effective indicator in a wide variety of air traffic control (ATC) facilities. Methods : Study 1 : The FAA’s Mandatory Occurrence Report (MOR) database was queried for “pilot deviations” AND “Airspace/Altitude/Route/Speed.” Study 2 : Alarm Development Phase: Air traffic controllers from the Terminal Computer Human Interface team considered essential properties needed for this new alarm. Alarm Testing Phase: The most important features were iteratively used to develop an alarm prototype and a short interview for air traffic controllers at a national conference. Controllers at the conference rated the effectiveness of the alarm and suggested applications. Results : Study 1 : The MOR database query revealed 113 reports of a trajectory deviation between August 1, 2023 and July 31, 2024. Study 2 : We found that a novel trajectory conformance alarm to signal that an aircraft is deviating from an RNAV arrival, approach, or departure was viewed favorably by controllers, and many proposed new applications for the alarm that could further improve the safety and efficiency of operations in the terminal environment. Conclusions : An Alarm Design Framework helped controllers to identify essential features and novel applications for a new trajectory conformance alarm.