Japan Airlines Flight 123 - Sequence of Events

Sequence of Events

The flight took off from Runway 16L at Tokyo International Airport (commonly referred to as Haneda Airport) in Ōta, Tokyo, Japan, at 6:12 p.m., 12 minutes behind schedule. About 12 minutes after takeoff, as the aircraft reached cruising altitude over Sagami Bay, the rear pressure bulkhead tore open. The resulting explosive decompression tore the tailfin from the aircraft and severed all four of the aircraft's hydraulic systems. A photograph taken from the ground some time later confirmed that the vertical stabilizer was missing. The loss of cabin pressure at high altitude had also caused a lack of oxygen throughout the cabin, and emergency oxygen masks for passengers soon began to fall. Flight attendants, including one who was off-duty and flying as a passenger, administered oxygen to various passengers using hand-held tanks.

The pilots, who were Captain Masami Takahama (高浜 雅己, Takahama Masami?), first officer Yutaka Sasaki (佐々木 祐, Sasaki Yutaka?), and flight engineer Hiroshi Fukuda (福田 博, Fukuda Hiroshi?), set their transponder to broadcast a distress signal. Tokyo Area Control Center directed the aircraft to descend and gave it heading vectors for an emergency landing. Continued control problems required the pilots to request vectors back to Haneda, then to Yokota (a U.S. military air base), then back again to Haneda as the aircraft wandered uncontrollably.

By then all hydraulic fluid had drained away through the rupture. With total loss of hydraulic control and non-functional control surfaces, the aircraft began to oscillate up and down in a phugoid cycle. The pilots managed a measure of control by using differential engine thrust. These improvisations proved helpful, but further measures to exert control, such as lowering the landing gear and flaps, interfered with control by throttle, and the plane's uncontrollability once again escalated.

After descending to 13,500 feet (4100 m), the pilots reported the aircraft's uncontrollability. The plane flew over the Izu Peninsula, headed for the Pacific Ocean, then turned back towards the shore and descended to below 7,000 feet (2100 m) before the pilots managed to return to a climb. The aircraft reached an altitude of 13,000 feet (4000 m) before entering an uncontrollable descent into the mountains and disappearing from radar at 6:56 p.m. and 6,800 feet (2100 m). The final moments of the plane occurred when it clipped one mountain ridge then crashed into a second one during another rapid plunge, then flipped and landed on its back. The aircraft's crash point, at an elevation of 1,565 metres (5,135 ft), is located in Sector 76, State Forest, 3577 Aza Hontani, Ouaza Narahara, Ueno Village, Tano District, Gunma Prefecture. The east-west ridge is about 2.5 kilometres (8,200 ft) north north west of Mount Mikuni. Ed Magnuson of Time magazine said that the area where the aircraft crashed was referred to as the "Tibet" of Gunma Prefecture.

Thirty-two minutes elapsed from the time of the bulkhead explosion to the time of the final crash, long enough for some passengers to write farewells to their families. Subsequent simulator re-enactments of the mechanical failures suffered by Flight 123 failed to produce a better solution or outcome, and none of the four flight crews in the simulations was able to keep the plane aloft for as long as the 32 minutes achieved by the actual crew.