United Airlines plane makes emergency SFO landing

A United Airlines flight this morning turned back to San Francisco International Airport because of a mechanical problem, an airport official said.

United Airlines Flight 1721 was on its way to Kona International Airport in Hawaii when it turned around and made an emergency landing.

Airlines spokeswoman Maggie Schmerin said the problem was a maintenance issue.

The plane landed safely at about 10:30 a.m. and another plane was going to be used to take the passengers on their trip.

That plane was expected to depart at 1 p.m. Pacific time, according to Schmerin.