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Boeing 737-4Q8 Plane crash, [KI-574]

1 Jan 2007

Adam Air Flight 574 (KI-574) was a normal domestic passenger flight operated by Adam Air between the Indonesian cities of Surabaya and Manado which disappeared near Polewali in Sulawesi on January 1, 2007. The Boeing 737-4Q8, was determined to have crashed into the ocean, from which some smaller pieces of wreckage have been later recovered. The flight recorders were retrieved from the bottom of the ocean on August 28, 2007, while salvage efforts for some larger pieces of wreckage continued. All 102 people on board are missing and presumed dead.

On 12:55 local time (05:55 UTC) January 1, 2007, the plane departed from Juanda Airport, Surabaya, with 96 passengers (85 adults, 7 children and 4 infants) and six crew on board. 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 14:53 local time (06:53 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.

A full national investigation was immediately launched into the disaster, and on the March 25, 2008, the inquiry ruled that pilot error and a faulty navigation device downed the airliner. Investigators found that, during the flight from Surabaya to Manado, the Inertial Reference System (IRS) malfunctioned.

Both pilots had became engrossed with trouble shooting the IRS anomalies for at least the last 13 minutes of the flight, with minimal regard to other flight requirements. The pilots selected Attitude in the IRS, which disengaged the autopilot. After the autopilot disengaged and the aircraft rolled right and exceeded 35 degrees right bank, the pilots appeared to have become spatially disoriented. The autopilot became disengaged and the pilots failed to correct for a slow right roll even after a "bank angle" alarm sounded. Despite the bank angle reaching 100 with almost 60 nose down attitude, the pilots did not level the wings before trying to regain pitch control. The aircraft reached 490 knots at the end of the recording, in excess of the aircraft's maximum rated speed for a dive (400 knots). The aircraft experienced a structural failure 20 seconds prior to the ending of the recording, at which time the investigators concluded the aircraft was in a "critically unrecoverable state".

Investigators also found that there had been two previous complaints that the weather radar was faulty. The weather radar fault is particularly important as it would explain why the aircraft flew into a storm, when evasive measures would normally be taken. Investigators quickly became concerned about apparent poor maintenance and believe it may play an important factor in the accident.

The Surabaya airport duty manager said that there were no technical problems with the aircraft prior to departure.

Indonesia Weather in the region was stormy the Indonesian Bureau of Meteorology and Geophysics noted that the cloud thickness was up to 30,000 feet (9,140 m) in height and wind speed at an average of 30 knots (56 km/h) in the area. Although the Juanda Airport operator, PT Angkasa Pura I, had given warnings to the pilot concerning the weather condition, the plane had departed as scheduled. The plane ran into crosswinds of more than 70 knots (130 km/h) over the Makassar Strait, which is West of Sulawesi, where it changed course eastward toward land and then lost contact. In his last radio transmission, the pilot reported the crosswinds to be coming from the left, but air traffic control claimed that the winds should be coming from the right. It is not yet known if this is significant to the accident, but it may indicate navigational error, or an emergency turn-around of the aircraft.

The flight data recorder was located at 0341'02?S, 11808'53?E at a depth of 2,000 metres (6,561.7 ft), while the cockpit voice recorder was located at 0340'22?S, 11809'16?E at a depth of 1,900 metres (6,233.6 ft). These positions indicate the black boxes are located approximately 1.4 km (0.9 mi) apart.

Adam Air has been accused by multiple organisations of poor maintenance and of ordering pilots to fly in all weather and regardless of aircraft conditions. Adam Adhitya Suherman, founder of the family-run airline, has personally denied these accusations, and has said that maintenance consumes "up 40 percent of our total operational costs". Despite this denial of any responsibility for the crash, Adam Air has compensated the families of deceased passengers Rp 500 million (equivalent to about US$55,000 or 42,000) per passenger. It also compensated families of the flight crew.

Even though the accident remains under investigation, the Indonesian government announced plans immediately after the accident to ban jets over ten years of age for any commercial purpose. The age limit was previously 35 years or 70,000 landings. Although this is in response to a large number of aircraft accidents, it is mainly in response to this accident and the Flight 172 incident. Adam Air ceased operation on March 18, 2008 after its Air Operator's Certificate was suspended by the Indonesian government.

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