Accountability starts with you
Leadership defines culture, and if you want to create a culture of accountability, then it starts with you. You need to model the behaviors that you want to see in your organization. If you want people to take ownership, then you have to be seen to take ownership, when you make commitments you have to be seen to meet those commitments. If you don't, then why should anyone else be interested in doing so. You have to walk the talk if you want others to follow you don't the accountability