Adam Air Flight 574

Adam Air Flight 574 was a scheduled domestic passenger flight operated by Adam Air between the Indonesian cities of Surabaya (SUB) and Manado (MDC) that crashed into the Makassar Strait near Polewali in Sulawesi on 1 January 2007. All 102 people on board were killed, the highest death toll of any aviation accident involving a Boeing 737-400.
Aircraft
The aircraft, a Boeing 737-4Q8, serial number 24070, registration PK-KKW, was manufactured in 1989. Prior to service with Adam Air, owned by ILFC the aircraft had been leased to seven airlines, including Dan-Air, British Airways, GB Airways, National Jets Italy, WFBN, Air One and JAT Airways. The plane has flown 45.371 hours and was last evaluated and declared airworthy by the Indonesian transport ministry on 25 December 2005.
Accident
On 1 January 2007, at 12:59 local time (05:59 UTC), the plane departed from Juanda Airport, Surabaya, with 96 passengers (35 adults, 47 children and 4 infants) and 6 crew on board. The passenger list was composed mainly of Indonesian nationals; the only foreigners were an American family of three. The two-hour flight, scheduled to arrive at Sam Ratulangi Airport, Manado, at 16:00 local time, was as expected until the plane disappeared from air traffic control radar screens at Makassar, South Sulawesi, with the last contact at 14:56 local time (06:56 UTC). The last known beacon position was detected by a Singaporean satellite. The altitude of the plane was shown as 35,000 feet (10,670 m) on the radar screen.
Captain Widodo and First Officer Susanto were both at the controls at the time of the accident. The aircraft was having issues with its navigation equipment. First Officer Susanto asked the Air Traffic Controller controlling the Makassar airspace their location and distance from the next waypoint. Instead of using that information to confirm their position, the flight crew decided to manually reset the aircraft's Inertial Reference System.
First Officer Susanto switches his IRS mode to ATT (or attitude) mode, and his attitude indicator screen goes blank. Because of this, Captain Widodo is required to fly the aircraft straight and level for 30 seconds. Because the pilots were focused on the navigation error, neither of them noticed that the autopilot had disconnected. The Boeing 737 slowly began to bank to the right, because an earlier unresolved maintenance error had put the ailerons slightly out of trim.
The increasing right bank goes completely unnoticed until Captain Widodo hears the bank angle warning. In response, he tells the first officer to put his IRS mode back on NAV. First Officer Susanto switches his mode back and attempts to take control of the aircraft to stop it from rolling into an inverted upset situation. Captain Widodo tells Susanto not to turn the aircraft, as he is still under the impression that the autopilot is keeping the aircraft on heading so that the IRS can realign itself. First Officer Susanto then tries to tell the captain that the aircraft is banking dangerously over to the right.
By the time the captain realizes what is actually happening, the aircraft is descending at negative 60 degrees nose down and 110 degrees of right bank. Captain Widodo takes control of the aircraft and attempts to roll the plane wings level, but is spatially disoriented by the lack of visual cues outside of the aircraft and completely ignores his attitude indicator. "Pull up, pull up!" First Officer Susanto screamed. Then, at a speed of Mach 0.926, Widodo pulls back on his yoke, contrary to existing upset recovery procedures. The horizontal stabilizers then separate from the aircraft, leaving it completely uncontrollable. The aircraft's G load then rapidly reverses from 3.5 G to negative 2.8 G, then continues to pick up speed until it crashes into the Makassar Strait.