In-person HAZOP study has been the traditional approach. It involves gathering a team of experts in a conference room, reviewing the system design, and identifying potential hazards and operability problems. The advantages of an in-person HAZOP study include the ability to build trust and rapport among team members, the ability to focus on the task at hand without distractions, and the ability to read non-verbal cues. Additionally, it is easier to maintain the confidentiality of the information discussed during the study.