
You argue that everybody knows the airworthiness certificate is the most important piece of paper because that document defines what airworthy is and sets the standards for it.

Why? In accordance with international agreements, the FAA cannot issue an airworthiness certificate or issue an airworthiness directive against an aircraft unless that aircraft is registered in the United States and an N number is assigned and displayed on the aircraft.
AVIATES ACRONYM FAR AIM REGISTRATION
The registration certificate is the most important regulatory document in the aircraft.

Since this kind of paperwork is important, I would now like to go over the four remaining pieces of paper and see how they apply to mechanics, repair stations, and air carrier maintenance departments. By the way, any suggestions that any of you might have on what the new acronym should be will be gratefully accepted. So now the acronym specialist in the FAA headquarters is pulling out his hair trying to come up with another buzz word so future “four stripers” can remember their paperwork requirements. 12, 1996, and on that same day it destroyed our “ARROW” acronym. The new FCC rule became effective on Dec. registered aircraft operating in the domestic U.S. Just when we had everybody trained for a fast and accurate pavlovian response, wouldn’t you know that another government agency, the Federal Communications Commission, would come along and drop the requirement to have a radio station license for all U.S.

If you ask any GA pilots what kind of aircraft paperwork the FAA requires them to have to have in the aircraft prior to flight, they will automatically respond with the acronym ARROW, which until just recently stood for airworthiness certificate, registration certificate, radio station license, operating manual, and weight and balance. March 1997 article from Aircraft Maintenance Technology
