United Adds Flights for Spirit Flyers in Case of Shut-Down (1)

United Airlines Holdings Inc. plans to increase daily flights to 15 US cities, a move it says would potentially help stranded passengers of Spirit Aviation Holdings Inc. but could also wind up further straining the financially strapped carrier.

The new 19 daily round-trip flights start Jan. 6 and will remain in United’s schedule going forward, the carrier said Thursday in a statement.

Spirit has told customers its most recent bankruptcy filing — the second in less than a year — will not impact the airline’s operations, tickets or loyalty program. There haven’t yet been any indications it plans to cease ...