The Near Midair Collision System (NMACS) database is used to record reports of in flight incidents where two aircraft have closed to an unsafe distance and avoided an actual collision.

The National Transportation Safety Board (NTSB) Aviation Accident and Incident Data System contains information collected during an NTSB investigation of an accident or incident involving civil aircraft within the United States, its territories and possessions, and in international waters. The NTSB Board is an independent Federal agency that investigates every civil aviation accident in the United States and significant accidents in the other modes of transportation, conducts special investigations and safety studies, and issues safety recommendations to prevent future accidents.

The National Transportation Safety Board (NTSB) uses the information it gathers during accident investigations and the determination of probable cause to make safety recommendations to all elements of the transportation industry. While the recipient of a recommendation does not have to implement the proposed action, it does have to respond formally to the recommendation and specify what action is or is not being taken and why. This database contains the NTSB recommendations to the FAA and the FAA responses.