Final report issued on the crash of Adam Air Flight 574

A final report on the crash of an Adam Air Boeing 737-400 (registration number PK-KKW) in January of 2007 has been issued by Indonesia's National Transportation Safety Committee (NTSC), the agency responsible for aircraft accident investigations in that country. The NTSC report concluded that the pilots lost control of the airliner after becoming preoccupied with malfunctioning navigational equipment -- specifically, the aircraft's Inertial Reference System (IRS) . The aircraft plunged into the sea at a high rate of speed. All 102 people on board were killed, including 96 passengers, four cabin crew, and the two pilots.

Adam Air Flight DHI-574 disappeared from radar on New Year's Day, 2007, during the cruise phase of a scheduled domestic flight between Surabaya (SUB), on the island of Java, to Manado (MDC), on Sulawesi island. After an extensive search on land and at sea some debris from the aircraft was found nine days after the accident.

On January 21, 2007, signals from the downed jetliner's flight data recorder were detected by an American ship that had been assisting with the search. The aircraft's Digital Flight Data Recorder (DFDR) and Cockpit Voice Recorder (CVR) finally were retrieved from the seabed in late August of 2007. Much of the NTSC's accident investigation centered on analysis of data from these recorders.

The Synopsis section of the NTSC's final report says the following:

The CVR revealed that both pilots were concerned about navigation problems and subsequently became engrossed with trouble shooting Inertial Reference System (IRS) anomalies for at least the last 13 minutes of the flight, with minimal regard to other flight requirements. This included identification and attempts at corrective actions.

The DFDR analysis showed that the aircraft was in cruise at FL 350 with the autopilot engaged. The autopilot was holding 5 degrees left aileron wheel in order to maintain wings level. Following the crew’s selection of the number-2 (right) IRS Mode Selector Unit to ATT (Attitude) mode, the autopilot disengaged. The control wheel (aileron) then centered and the aircraft began a slow roll to the right. The aural alert, BANK ANGLE, sounded as the aircraft passed 35 degrees right bank.

The DFDR data showed that roll rate was momentarily arrested several times, but there was only one significant attempt to arrest the roll. Positive and sustained roll attitude recovery was not achieved. Even after the aircraft had reached a bank angle of 100 degrees, with the pitch attitude approaching 60 degrees aircraft nose down, the pilot did not roll the aircraft’s wings level before attempting pitch recovery in accordance with standard operating procedures. The aircraft reached 3.5g, as the speed reached Mach 0.926 during sustained nose-up elevator control input while still in a right bank. The recorded airspeed exceeded Vdive (400 kcas), and reached a maximum of approximately 490 kcas just prior to the end of recording.

A thump, thump sound was evident on the CVR about 20 seconds from the end of the recorded data. Flight recorder data indicated that a significant structural failure occurred when the aircraft was at a speed of Mach 0.926 and the flight load suddenly and rapidly reversed from 3.5g to negative 2.8 g. This g force and airspeed are beyond the design limitations of the aircraft. At the time of the thump, thump sound, the aircraft was in a critically uncontrollable state. [NTSC Accident Investigation Report No. KNKT/07.01/08.01.36, Synopsis, pp. 1-2]

The report faulted the pilot in command for failure to manage crew task sharing, and for not following crew resource management practices. The report noted, "There was no evidence that the pilots were appropriately controlling the aircraft, even after the BANK ANGLE alert sounded as the aircraft’s roll exceeded 35 degrees right bank."

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 Inertial Reference System (IRS) diverted both pilots’ attention from the flight instruments and allowed the increasing descent and bank angle to go unnoticed. The pilots did not detect and appropriately arrest the descent soon enough to prevent loss of control. [NTSC Accident Investigation Report No. KNKT/07.01/08.01.36, Synopsis, p. 2]

Among the other factors that contributed to the cause of the accident, the report found that the carrier, privately owned Adam Air, "did not provide their pilots with IRS malfunction corrective action training in the simulator, nor did they provide aircraft upset recovery training in accordance with the Airplane Upset Recovery Training Aid developed by Boeing and Airbus." Adam Air management also was faulted for being unaware of the seriousness of "unresolved and recurring defects" related to the aircraft's Inertial Reference System, referring to the finding that maintenance records and pilots' reports showed that there were 154 such defects reported between October and December of 2006. As well, the report noted several failings by Indonesia's Directorate General of Civil Aviation (DGCA) to properly oversee Adam Air's fleet maintenance practices.

The entire report has been posted to the NTSC website. Here is the link:

NTSC Accident Investigation Report No. KNKT/07.01/08.01.36 - NTSC of Indonesia, March 25, 2008

This is a 98-page 'pdf' file, so it may take awhile to load.

A shorter summary is available as a part of a media release issued by the NTSC, announcing their report (4-page 'pdf' file).

Related: Click here to view all posts about Adam Air Flt 574 on Aircrew Buzz.