Ok, now it is official.
Could the NTSB impose mandatory airworthiness directives about Pitot probes although the AESA seems reluctant to do so
Hyperveloce, the NTSB can investigate and make recommendations to a regulating agency that a certain action be taken. The FAA, as a regulatory agency, would issue any ADs.
The NTSB's recommendations are not binding on a regulatory agency.
In this instance, the NTSB has authority to investigate, as one flight originated in the United States, and the other flight was a U.S. airline