United Airlines is expected to ground dozens of its least-fuel-efficient aircraft, including Boeing 747 jumbo jets, as part of a sweeping round of cuts intended to help the carrier conserve cash and survive as a stand-alone company in daunting times.

The Chicago-based airline intensified planning for the initiative as it cooled on a potential merger with US Airways in mid-May, say people familiar with its plans.

United already had planned to ground all of its 30 Boeing 737-500s, which seat just 108 passengers but burn as much fuel as the larger, narrow-body jets that it uses for flights within North America.