A056 LOAs can be issued for FANS 1/A+ (oceanic), ATN B1 (European over land), or both depending on how the aircraft is equipped. A056 requests are initially submitted to the Operator’s local FSDO via email or USB drive. The FSDO inspectors conduct an initial review, then the request is uploaded to a regional navigation specialist for more in-depth review. The regional navigation specialists often take many months to review CPDLC requests.
Part 91 A056 LOAs are not required for US domestic datalink operations. They are required for oceanic and European operations.