Investigation Summary
Flight 533 was operating a domestic scheduled service from Osaka to Matsuyama, departing 85 minutes behind schedule. During the flight, the crew expressed concerns regarding the reliability of the Matsuyama NDB, which had been temporarily closed but was resumed shortly before their arrival. Upon reaching Matsuyama, the aircraft was cleared for a visual approach to Runway 31. The approach was steeper and higher than standard, resulting in a touchdown 460 meters past the threshold. The pilots opted to perform a go-around after a brief 170-meter ground roll. While the aircraft initially climbed to a height between 70 and 100 meters (approximately 230 to 330 feet), it began a left turn and subsequently lost altitude. The aircraft struck the water in a nose-down, left-banked attitude with the landing gear and flaps fully retracted. Despite extensive investigation, no technical malfunctions were identified, and the specific reason for the loss of altitude remained a mystery.
Final Conclusions
The official investigation concluded that the aircraft crashed into the sea following a go-around initiated after a long touchdown. The reason why the aircraft lost altitude during the subsequent left turn could not be determined. Factors noted included a shallower than normal climb out and a turn initiated at a lower than normal altitude.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Copilot
Systems & Failure Modes
Matsuyama NDB
A non-directional beacon used for navigation; the crew questioned its reliability shortly before the approach.
Flaps and Undercarriage
Post-crash investigation confirmed these were fully retracted, consistent with a clean configuration for climb or cruise.
Interesting Facts
- 01The accident was the fifth major aviation disaster in Japan during the year 1966.
- 02The aircraft was a NAMC YS-11, a Japanese turboprop airliner that had only recently entered service.
- 03The aircraft's Manufacturer Serial Number (MSN) was 2023.
- 04At the time of impact, the aircraft was in a nose-down attitude with a left bank, and all landing gear and flaps were retracted.
- 05The crash occurred in the Seto Inland Sea, approximately 450 meters northeast of where the empennage was later recovered.
- 06The flight number NH533 was later reassigned to a route between Haneda and Takamatsu.
Safety Actions & Advisories
Mandatory Flight Data Recorder Installation
Following a series of five major aviation disasters in Japan during 1966, including Flight 533, the Japanese Ministry of Transport mandated the installation of flight data recorders (FDR) and cockpit voice recorders (CVR) on all domestic commercial aircraft to aid future accident investigations.