Joining the exhaustive list of air carriers that have gone in for cash-free cabins is the No. 2 carrier at Sacramento International Airport - the United Airlines! Southwest Airlines and US Airways are the other airlines to have already changed over to credit-only cabins.

A couple of days back, the airline announced its intention of doing away with cash transactions for passenger purchases of cocktails or other items on board its flights, and would only be accepting credit and debit cards.

United airlines' domestic flights, as well as those to and from Canada, Mexico, Central America and the Caribbean will entail the changeover to plastic on board. However, for the carrier's other international flights, cash will still be accepted along with the credit and debit cards.

Similar to the other carriers that use plastic, United's "EasyPurchase" plan will enable flight crew members to make the transactions using hand-held readers.

Though the Chicago-based United Airlines - a UAL Corp division - will kick off the transition to plastic aboard flights on March 23, the airlines will allow its passengers the cash option during the course of its "brief transition period," which is yet to be specified by the carrier.