Originally Posted by
chavala
Is this new "rule" published ANYWHERE? As someone who often travels with U/W camera gear I'd be livid if they made me check it without any warning.
As mentioned this UX carrier and aircraft specific but
UA does state
United Express flights are served by regional partner carriers using smaller aircraft than United's mainline fleet. Aircraft in the United Express fleet generally have less room in the overhead bins for carry-on baggage, and in most cases roller bags and other larger carry-on items will not fit in United Express overhead bins. As a result, you may need to gate-check these items before boarding.
And this is not a new rule, it has been true (but enforcement varies) for many years.
The CRJ200 or EMB145 are where you need to be asking questions.