United Airlines Faces Fourth Emergency Landing in a Week

• United Airlines flight from San Francisco to Mexico City diverted to LA due to issue with plane’s hydraulic system

• This was United's 4th emergency landing in past week, including dropped tire and engine fire

• The Airbus A320 landed safely in LA; 105 passengers flown to Mexico City on different plane

• United says each incident is unrelated and will investigate each one

• Recent incidents include engine ingesting bubble wrap and catching fire midair Monday and a plane skidding off runway Friday