Originally Posted by
Stripe
I had no idea the FAA regulated carry on bags except for items like liquids, which the TSA enforces, and mandating that everything fits fully under the seat or in an overhead. What are the specific regulations about size? I can't find any searching online. If a carry on bag won't fit then it can't stay in the cabin. And whether a specific bag will fit can vary among aircraft types. I can understand the airline itself wanting to control sizes to ensure a smooth boarding process but I confess I don't understand the whole FAA audit thing.
It is a bit more nuanced. It is up to the carrier, AA in this case, to create a policy dealing with safety & security. That policy is then filed with the FAA and it becomes a violation of FAA rules for the carrier to fail to enforce its own policy. Among the items which the policy must cover are carry on limits.
Thus, different carriers may have different policies, but the FAA concern is that each carrier enforce its own policy. The same for other items such as whether passengers on domestic flights may move between cabins.