In the context of aviation and aerospace, "ATS Interfacility Data Communications" refers to the exchange of data between different air traffic control facilities, such as Area Control Centers (ACCs), Approach Control facilities, and Air Traffic Control Towers.

ATS stands for "Aeronautical Telecommunication Services," which encompasses a range of communication services used in air traffic management, including voice and data communications. Interfacility Data Communications (IDC) specifically refers to the automated exchange of data between air traffic control facilities, using standardized protocols and interfaces.

The purpose of ATS Interfacility Data Communications is to facilitate the efficient exchange of flight-related data, such as:

1. Flight plans
2. Flight progress information
3. Air traffic control clearances
4. Weather information
5. Aeronautical information

This data is exchanged between facilities to support air traffic management functions, such as:

1. Flight planning and coordination
2. Air traffic control decision-making
3. Separation of aircraft
4. Conflict detection and resolution

The use of ATS Interfacility Data Communications enables air traffic control facilities to share information in a standardized and automated manner, which helps to:

1. Improve air traffic management efficiency
2. Enhance safety
3. Reduce delays
4. Increase the accuracy of air traffic control decisions

Examples of ATS Interfacility Data Communications systems include:

1. The Aeronautical Fixed Telecommunication Network (AFTN)
2. The Air Traffic Services Interfacility Data Communications (ATS IDC) system
3. The System Wide Information Management (SWIM) program

These systems use standardized protocols, such as the International Civil Aviation Organization (ICAO) ATS Message Handling System (AMHS) and the Federal Aviation Administration (FAA) Interfacility Data Communications (IDC) protocol, to exchange data between facilities.