On the evening of June 30, multiple netizens posted about an in-flight emergency on Spring Japan flight IJ004 from Shanghai to Tokyo.
Midway through the flight at cruising altitude, a mechanical failure triggered the deployment of oxygen masks. The aircraft rapidly descended from 11,000 meters to 3,200 meters within 10 minutes and eventually made an emergency landing at Osaka Kansai Airport.
According to Japan’s Ministry of Land, Infrastructure, Transport and Tourism and other agencies, the aircraft issued a "pressurization system failure" alert. The pilots declared an emergency with air traffic control before landing.
The airline is currently investigating the specific cause of the incident.
Though branded as “Spring Japan,” this flight was not operated by mainland China’s Spring Airlines (code 9C), but by Spring Japan (flight code IJ). The two carriers share equity ties but operated under separate legal and regulatory frameworks.
Spring Japan, formerly Spring Airlines Japan, was established in 2012 as a low-cost carrier jointly owned by China’s Spring Airlines and Japan Airlines (JAL).
Due to Japan’s foreign investment restrictions in aviation, in July 2021, Japan Airlines increased its stake, reducing Spring Airlines’ ownership from 56% to 30%. JAL now holds a two-thirds majority, making Spring Japan its subsidiary.
Following the incident, mainland Spring Airlines quickly clarified that its own 9C flights were operating normally. However, the distinction between “Spring Airlines” and “Spring Japan” remains confusing to many passengers and the general public.
Flight IJ004 flying from Shanghai Pudong to Tokyo Narita, is one of the busiest international routes between China and Japan.
Data shows that in 2024, the Shanghai-Tokyo route alone has more than 20 round-trip flights daily.
The aircraft involved was a Boeing 737-8AL (a customer-specific variant the 737-800), with an average age of 7.2 years. It had completed 28 flights in the past 30 days.
Since the Boeing 737 MAX grounding scandal, public confidence in Boeing aircraft safety has eroded.
The 737-800 remains the most widely operated model in the Boeing 737 family, with over 5,000 units in service globally, many with low-cost carriers.
In recent years, the 737 series has frequently drawn attention for safety concerns. United Airlines, Jetstar Australia, and others have reported cabin pressurization failures resulting in emergency descents. However, no global recalls or mandatory system-wide inspections have been initiated to date.
