An Alaska Airlines Boeing 737-400 has been removed from service after cabin pressure was reduced following undisclosed "issues" with the electrical system for onboard computers.
The electrical malfunction occurred after the 737, with registration N797AS, reached about 25,000ft around 20min after take-off from Ontario, California, the airline says.
Although the cabin experienced a loss of cabin pressure, the oxygen masks for passenger did not deploy, the airline adds.
The flight crew descended to 10,000ft and manually repressurised the cabin, the airline says. The aircraft was en route to Seattle, but was cleared by air traffic control to divert to San Jose, California. No injuries were reported, the airline says.
The aircraft is being inspected by maintenance staff, Alaska Airlines says.
The 737-400 entered service in April 1998, and is owned by aircraft lessor GECAS. The aircraft has accumulated 45,077h on 24,973 cycles, according to the Flightglobal Pro database.
Alaska Airlines operates 30 737-400s, or one-fourth of its fleet.