The United Airlines and Canadair Regional Carry-On Size
Canadair, a now defunct manufacturer of Canadian airplanes, focused primarily on making small, regional jets. Among their creations was the CRJ, short for Canadair regional jet. These small planes are still used by many large airlines to shuttle passengers on short flights. Because these planes are relatively small, bags that on other airplanes could be taken carry-on must be checked. The exact dimensions of bags that can be taken carry-on on these flights depends on the model of the plane.
United Carry-On Policies
According to United Airlines' written policies, a passenger is allowed to take one bag and one personal item, such as a laptop bag or a purse, onto the aircraft. All additional bags must be checked, which will cost you a fee unless you have Star Alliance Silver or higher status. The maximum linear measurement of the carry-on bag must not exceed 14 inches by 9 inches by 22 inches. However, in all cases, these bags must fit in the overhead compartment or below the seat in front of you. Therefore, if the plane is especially small, you may still have to check some bags that meet these dimensions.
United CRJ Planes
As of 2013 United Airlines flies two CRJ planes, the CRJ-200 and the CRJ-700. Both of these planes carry between 50 and 66 people and are only flown on short trips.
The maximum dimensions for the overhead compartment on the CRJ-200 is 18 long by 14 inches wide by 7 inches deep -- dimensions somewhat smaller than those allowed under United's policies. Due to these restrictions, luggage larger than this must be checked at the aircraft door.
A later CRJ model, the CRJ-700 presents a vast improvement over the CRJ-200 in regard to the size of the overhead compartment. On the CRJ-700, the overhead bins are 52.5 inches wide by 14 inches high and 9.5 inches deep. On later models of the CRJ-700, the size of the bin was expanded still further to accommodate bags that are 10 inches by 16 inches.
It's worth noting that United's baggage policy specifically states that passengers will be charged a fee to check bags that exceed the dimensions 14 inches by 9 inches by 22 inches. However, you will NOT be charged for bags that do not exceed these dimensions but that for other reasons -- such as the plane being exceptionally small -- must be checked through. An airline agent will likely give you a tag at the gate to place on your bag and then you leave your bag at the end of the jet bridge for the baggage handler to collect. When you arrive at your destination, confirm with the crew whether your bag will be available on the jet bridge or at baggage claim.