A United Airlines flight that departed San Francisco was forced to make an emergency landing in Los Angeles early Friday evening due to problems with the aircraft’s hydraulic system, according to airline officials. It marked the fourth domestic flight emergency just this week for the airline.  

The airline said in a statement that United Flight 821 from San Francisco International Airport to Mexico City International Airport departed at around 1 p.m. local time carrying 105 passengers and five crew members, and was diverted to L.A. International Airport because of an issue with the aircraft’s hydraulic system. 

The aircraft, an Airbus 320, landed safely and passengers were deplaned at the gate without issue, the statement read. Customers would continue their travel to Mexico City on a new aircraft scheduled to depart later Friday evening.

The airline noted that the aircraft has three hydraulic systems for “redundancy purposes,” and “preliminary information shows there was only an issue with one system on this aircraft.”

On Friday morning, United Flight 2477 from Memphis, Tennessee, carrying 160 passengers and six crew members, veered off the runway and into the grass just after landing at George Bush Intercontinental Airport in Houston. The passengers were forced to depart the plane using air stars on the open runway. No one was hurt.

Those followed far more dramatic issues with another flight out of San Francisco on Thursday, when a United jet bound for Osaka, Japan, lost a tire as it was taking off from SFO.

Airport officials said the incident happened at around 11:35 a.m. when United Flight 35 lost a piece of its landing gear. The tire, which could be seen falling from the jet’s landing gear in video from the ground, landed in an employee parking lot at the airport and damaged two vehicles. The tire crushed one vehicle.

The flight landed safely at Los Angeles International Airport around 1:20 p.m. The flight had a total of 249 people on board.

“The 777-200 has six tires on each of its two main landing gear struts. The aircraft is designed to land safely with missing or damaged tires,” said a United Airlines spokesperson.

And on Monday, United Flight 1118 bound for Fort Myers, Florida, was forced to immediately return to Bush Intercontinental Airport after the engine caught fire shortly after takeoff. The airline said that an investigation determined that bubble wrap had been sucked into the engine.