Definition
A jointly published technical standard from RTCA (a U.S. aviation standards organization) and EUROCAE (its European counterpart) that defines the requirements aircraft and ground systems must meet to exchange digital messages over the Aeronautical Telecommunication Network (ATN) at its first operational baseline. ATN Baseline 1 covers the initial set of controller-pilot data link communications (CPDLC) and related air traffic services, ensuring that equipment from different manufacturers and different countries can communicate reliably with each other.
Plain English
It is the rulebook, agreed between U.S. and European aviation authorities, that says how aircraft and air traffic control computers must talk to each other digitally so that everyone's equipment works together properly.
Context Anchor
Seen in instrument procedures and avionics discussions where RNAV, data communication, and certified equipment standards are being described.
Derivation
RTCA originally stood for Radio Technical Commission for Aeronautics; today it operates simply as RTCA. EUROCAE is the European Organisation for Civil Aviation Equipment. ATN means Aeronautical Telecommunication Network, the digital network used for air traffic services. 'Baseline 1' marks the first agreed feature set, with later baselines adding more capability. Knowing the parts helps: it is a U.S./European joint standard, for the aviation digital network, at its first stage.
Why Pilots Care
Aircraft certified to this standard can use data link services such as CPDLC across U.S. and European airspace without compatibility problems. For pilots, this means text-based clearances and reports work the same way regardless of which controller or which avionics manufacturer is involved.
Analogy
It is like a common phone-charging standard: the aircraft and ground system may be made by different companies, but the agreed standard lets them connect and communicate correctly.
Intuition Check
Do not read “Baseline 1” as “basic” or “less important.” Here it names a specific approved version of ATN data communication requirements.
Example Sentence 1
The aircraft's data link system was certified to the RTCA/EUROCAE Interoperability Requirements Standard for ATN Baseline 1, allowing it to use CPDLC in both domestic and European airspace.
Example Sentence 2
Operators must confirm their fleet meets the RTCA/EUROCAE Interoperability Requirements Standard For ATN Baseline 1 to participate in controller-pilot data link communications.