Adam Air Flight 574

Adam Air Flight 574 was a scheduled domestic passenger flight operated by an Adam Air Boeing 737-400 between the Indonesian cities of Jakarta, Surabaya, and Manado that crashed into the Makassar Strait near Polewali in Sulawesi on 1 January 2007. All 102 people on board were killed, making it the deadliest aviation accident involving a 737-400. After this, Adam Air faced intense scrutiny by the Indonesian government, which launched a national investigation into the disaster. The government's final report, released on 25 March 2008, concluded that the pilots lost control of the aircraft after they became preoccupied with troubleshooting the inertial navigation system and inadvertently disconnected the autopilot. Despite a series of safety incidents, which contributed to the shutdown of Adam Air in 2008, this was the only incident resulting in fatalities during the airline's 5-year existence.

Together with the subsequent crash of Adam Air Flight 172 and several other transportation accidents, the crash contributed to the United States' downgrading of its safety rating of Indonesian aviation. This eventually led to large-scale transportation safety reforms in Indonesia. All Indonesian airlines were banned from flying into the European Union for several years after the crash. After numerous warnings by the authorities for Adam Air to implement safety regulations went unheeded, the airline was banned from flying by the Indonesian government in March 2008, and declared bankruptcy in June of the same year.

Flight chronology

On 1 January 2007, at 12:59 local time (05:59 UTC), the plane departed from Juanda Airport, Surabaya, with 96 passengers (85 adults, seven children, and four infants), a 56% load factor, and 6 crew on board. The passenger list was composed mainly of Indonesian nationals with a majority of the passengers returning to Manado after New Year's Day; the foreigners were an American family of three and a German national. The two-hour flight, scheduled to arrive at Sam Ratulangi Airport, Manado, at 16:00 local time, was normal until the plane vanished from air traffic control radar screens at Makassar, South Sulawesi, with the final contact at around 15:00 local time. The last known beacon position was detected by a Singaporean satellite. The altitude of the plane was shown as 35000 ft on the radar screen.

Weather in the region was stormy; the Indonesian Bureau of Meteorology and Geophysics noted that the cloud tops were up to 30000 ft in altitude with an average wind speed of 30 kn in the area. Although the Juanda Airport operator, PT Angkasa Pura I, had given the pilot the weather conditions, the plane departed as scheduled. The plane ran into crosswinds of more than 70 kn over the Makassar Strait, west of Sulawesi, where it changed course eastward toward land before losing contact.

Problems started when the pilots noticed an anomaly in the inertial reference system (IRS). The first officer then attempted to troubleshoot, resetting his IRS unit by switching the knob on his side to Attitude (ATT) mode; this disengaged the autopilot with a 4-second autopilot disconnect tone, effectively requiring the captain to take control and fly the plane straight and level for 30 seconds as the realignment process was completed. Neither crew member noticed the autopilot was no longer engaged, and the captain did not take control. Previous maintenance issues involving the aircraft's ailerons caused the airplane to slowly roll to the right and the nose to drop. When the aircraft reached 35° right bank and increasing, a "bank angle" audible warning sounded in the cockpit.

This accident resulted from a combination of factors, including the failure of the pilots to adequately monitor the flight instruments, particularly during the final 2 minutes of the flight. Preoccupation with a malfunction of the IRS diverted both pilots' attention from the flight instruments and allowed the increasing bank angle and descent to go unnoticed. The pilots did not detect and appropriately arrest the descent soon enough to prevent loss of control.

Captain Widodo told the first officer to switch the IRS mode back to NAV, to hopefully reverse the situation. Now that the first officer's attitude indicator had returned to its normal state, First Officer Susanto could see that the aircraft was in a dangerous position, and attempted to notify the captain. When this failed, he then tried to recover the aircraft from its descent by turning the yoke to the left. Believing that the aircraft was flying straight and level, Captain Widodo then unknowingly reminded First Officer Susanto that the aircraft needed to fly straight and level to complete the IRS alignment process. The aircraft was now in a 100° right bank with a 60 nose-down attitude. First Officer Susanto successfully notified the captain of their situation. In response to the first officer telling him to pull up to stop the rapid descent towards the sea, Captain Widodo pulled back on his yoke, and the aircraft, travelling at Mach 0.926 (92.6% the speed of sound), experienced a force 3.5 times the force of gravity at a calibrated airspeed of 490 knots (well above its maximum speed) and began to break apart in-flight. All recordings stopped at 9,000 feet, presumably because the aircraft had fully broken apart.

No distress signals were sent by the aircraft.

Flight 172

On 21 February 2007, just 51 days after the loss of Flight 574, Flight 172, an Adam Air Boeing 737-300 aircraft (registration PK-KKV) flying from Jakarta to Surabaya had a hard landing at Juanda International Airport. The incident caused the fuselage of the plane to crack and bend in the middle, with the tail of the plane drooping towards the ground. No serious injuries from the incident were reported. As a result, six Adam Air 737s were grounded awaiting safety checks. Adam Air described this as "harsh punishment" for an accident it blamed on poor weather conditions, but Vice-president Kalla had said that all Boeing 737-300s should be checked.