Final answer:
The hearing phase of a certification action appeal is heard and decided by a National Transportation Safety Board (NTSB) Administrative Law Judge (ALJ).
Step-by-step explanation:
At the hearing phase of certification action appeal, the case is heard and decided by the National Transportation Safety Board (NTSB) Administrative Law Judge (ALJ). The ALJ conducts the hearing and makes a determination based on the evidence and testimonies presented during the process.
This judge functions within the NTSB, which is an independent federal agency charged with investigating civil transportation accidents and incidents, including those related to aviation.