This presentation will provide an overview of how research and data analysis helped shape the fire protection system requirements in NFPA 409 (2022 edition) to allow consideration of automatic sprinklers as part of a viable fire protection solution. The process of how and why the changes were incorporated into NFPA 409 which now allows fire protection decisions to be made based upon a fire risk assessment, will be presented. The fire risk assessment method considers factors such as hangar classification, operations and activities conducted within the hangar, and previous loss history. An overview of the fire risk assessment process will be provided to explain the details and importance of following the approach outlined in NFPA 409, and how this approach can and has been used in aircraft hangars. The presentation will also include data of fire incidents and automatic suppression system operation in hangars.