Boeing 747SR-46

Seven 747SR-46 airframes were built for Japan Airlines between 1973 and 1975, all powered by Pratt & Whitney JT9D-7A engines and configured for up to 498 passengers on domestic Japanese routes. The only fatal hull loss was JAL Flight 123 in 1985 (520 fatalities). The type was retired from passenger service by the early 2000s as JAL transitioned to 747-400Ds and twinjets.

In BlackBoxWiki Archive

Built for the Domestic Trunk

The 747SR-46 was Boeing's answer to a very specific Japanese problem: enormous passenger volumes between Tokyo, Osaka, Sapporo and Fukuoka over sectors too short to justify a long-haul 747. Boeing reinforced the fuselage, wings and landing gear so the airframe could endure roughly 52,000 pressurisation cycles — more than double the baseline 747-100 design life. To offset the added structural weight, fuel capacity was cut by about 20 percent, giving the type a range of only around 2,200 nm but allowing a single-class capacity approaching 500 seats.

The Tailstrike That Became a Time Bomb

On 2 June 1978, JA8119 — the aircraft later lost as JAL 123 — suffered a tailstrike while landing at Osaka-Itami on Japan Airlines Flight 115. The aft pressure bulkhead was repaired using a single-row rivet splice instead of the required double-row pattern, reducing its fatigue resistance by an estimated 70 percent. The repair was signed off and the aircraft returned to service, but the weakened bulkhead was now a latent defect waiting for the right cycle count.

JAL 123 and the Loss of Everything Hydraulic

On 12 August 1985, the repaired bulkhead ruptured explosively about twelve minutes after departure from Tokyo-Haneda. The overpressure severed all four independent hydraulic lines and destroyed most of the vertical stabiliser. With no conventional flight controls, the crew fought the aircraft for 32 minutes using engine thrust alone before the 747SR-46 crashed into the mountains of Gunma Prefecture. Of 524 people on board, only four survived; the 520 fatalities make it the deadliest single-aircraft accident in history.

Retirement of the Concept

The 747SR family outlived the accident by two decades, but the original -46s left JAL's fleet in the 1990s and the last 747SR-based aircraft were retired by 2006. The high-cycle domestic concept lived on in the Boeing 747-400D, which also lacked winglets and was optimised for short Japanese sectors, before twins such as the 777 and later the 787 took over the role.

Notable Accidents

• Japan Airlines 115· 1978
  Tailstrike at Osaka-Itami on JA8119; the subsequent aft pressure bulkhead repair was done with a single-row splice instead of the required double row.
• Japan Airlines 123· 1985
  Aft pressure bulkhead rupture destroyed the vertical stabiliser and all hydraulics; 520 fatalities, the deadliest single-aircraft accident in history.