Loss of control and poor CRM cited in fatal Ethiopian Boeing 737 accident near Lebanon

Flight ET409 flight profile

The Lebanese Ministry of Public Works & Transport released their investigation progress report regarding the January 2010 fatal accident involving a Ethiopian Flight 409 off the coast of Beirut.

On January 25, 2010 a Boeing 737-8AS (WL) passenger jet, registered ET-ANB, was destroyed in an accident 6 km southwest off Beirut International Airport (BEY), Lebanon. All 82 passengers and eight crew members were killed. The airplane operated on Ethiopian Airlines flight ET409 from Beirut International Airport (BEY) to Addis Ababa-Bole Airport (ADD).

The flight departed at night on an instrument flight plan. Low clouds, isolated cumulonimbus (CB) and thunderstorms were reported in the area. After take-off ATC (Tower) instructed ET 409 to turn right on a heading of 315°. ET 409 acknowledged and heading 315° was selected on the Mode Control Panel (MCP). As the aircraft was on a right turn, Control suggested to ET 409 to follow heading 270° “due to weather”. However, ET 409 continued right turn beyond the selected heading of 315° and Control immediately instructed them to “turn left now heading 270°”. ET 409 acknowledged, the crew selected 270° on the MCP and initiated a left turn.
ET 409 continued the left turn beyond the instructed/selected heading of 270° despite several calls from ATC to turn right heading 270° and acknowledgment from the crew. ET 409 reached a southerly track before sharply turning left until it disappeared from the radar screen and crashed into the sea about five minutes after the initiation of the take-off roll. The flight recorder data revealed that ET 409 encountered during flight two stick shakers for a period of 27 and 26 seconds. They also recorded 11 “Bank Angle” aural warnings at different times during the flight and an over-speed clacker towards the end of the flight. The maximum recorded AOA was 32°, maximum recorded bank angle was 118° left, maximum recorded speed was 407.5 knots, maximum recorded G load was 4.76 and maximum recorded nose down pitch value 63.1°.

Probable causes:

1. The flight crew’s mismanagement of the aircraft’s speed, altitude, headings and attitude through inconsistent flight control inputs resulting in a loss of control.
2. The flight crew failure to abide by CRM principles of mutual support and calling deviations hindered any timely intervention and correction.

Contributing factors:

1.  The manipulation of the flight controls by the flight crew in an ineffective manner resulted in the aircraft undesired behavior and increased the level of stress of the pilots.
2.  The aircraft being out of trim for most of the flight directly increased the workload on the pilot and made his control of the aircraft more demanding.
3.  The prevailing weather conditions at night most probably resulted in spatial disorientation to the flight crew and lead to loss of situational awareness.
4.  The relative inexperience of the Flight Crew on type combined with their unfamiliarity with the airport contributed, most likely, to increase the Flight Crew workload and stress.
5.  The consecutive flying (188 hours in 51 days) on a new type with the absolute minimum rest could have likely resulted in a chronic fatigue affecting the captain’s performance.
6.  The heavy meal discussed by the crew prior to take-off has affected their quality of sleep prior to that flight.
7.  The aircraft 11 bank angle aural warnings, 2 stalls and final spiral dive contributed in the increase of the crew workload and stress level.
8.  Symptoms similar to those of a subtle incapacitation have been identified and could have resulted from and/or explain most of the causes mentioned above. However, there is no factual evidence to confirm without any doubt such a cause.
9.  The F/O reluctance to intervene did not help in confirming a case of captain’s subtle incapacitation and/or to take over control of the aircraft as stipulated in the operator’s SOP.

More information:

• Investigation Report Ethiopian 409 Accident – Boeing 737-800 25th January 2010 Beirut – Lebanon
• ASN Accident Description

Lebanon releases progress report on fatal Ethiopian Boeing 737-800 accident investigation

Flight ET409 flight profile

The Lebanese Ministry of Public Works & Transport released their investigation progress report regarding the January 2010 fatal accident involving a Ethiopian Flight 409 off the coast of Beirut.

On January 25, 2010 a Boeing 737-8AS(WL) passenger jet, registered ET-ANB, was destroyed in an accident 6 km southwest off Beirut International Airport (BEY), Lebanon. All 82 passengers and eight crew members were killed. The airplane operated on Ethiopian Airlines flight ET409 from Beirut International Airport (BEY) to Addis Ababa-Bole Airport (ADD).

The progress report indicated that IMC prevailed for the flight, and the flight was on an instrument flight plan. It was night in dark lighting conditions with reported isolated cumulonimbus clouds and thunderstorms in the area.
Flight ET409 was initially cleared by ATC on a LATEB 1 D Standard Instrument Departure (SID) from runway 21. Just before take-off, ATC changed the clearance to an “immediate right turn direct Chekka”.
The Boeing 737 took off from runway 21 at 02:36. After take-off ATC instructed ET409 to turn right on a heading of 315° and change frequencies and contact Beirut Control. ET409 acknowledged the clearance and continued a right turn. ATC instructed ET409 to turn left heading 270°, which was acknowledged. The flight continued the climbing left turn to heading 270° but did not maintain that heading. The aircraft continued on a southerly track. Just prior to reaching  altitude of 7700 feet, the stick shaker activated, sounding for a period of 29 seconds. Meanwhile the airplane reached an angle of attack (AOA) of 32° and began a descent to 6000 feet. When the stick shaker ceased, the aircraft began to climb again. At 02:40:56, just prior to reaching 9000 feet, the stick shaker activated again, sounding for a period of 26 seconds.

After reaching 9000 feet the aircraft made a sharp left turn and descended rapidly. The maximum registered bank angle was 118° left and the airplane reached a maximum registered speed was 407.5 knots at a G load of  4.412. The airplane disappeared from the radar screen and crashed into the Mediterranean Sea at 02:41:30.

Additional preliminary facts established by the investigators:

• The aircraft weight and balance record was reviewed and no deficiencies or anomalies were noted.
• No defect or deferred maintenance item was reported on the technical log after the arrival and before departure of the plane from Beirut.
• The examination of the maintenance documents on this aircraft did not reveal any significant anomalies.
• Based on the elements recovered up to 24 Feb, 2011 and the visual observation, no evidence of fire has been brought up.
• The Flight Crew and Cabin Crew were licensed in accordance with the ECAA regulations.
• The documents received by the Flight Crew prior to departure, including weather information, were in accordance with the relevant requirements.
• The Captain had a total flying experience of 10,233 hours of which 188 hours on B 737-700/800.
• The First Officer  had a total flying experience of 673 hours of which 350 hours as F/O on B 737-700/800.

The investigation is on-going.

More information:

• Investigation Progress Report Ethiopian 409 Accident – Boeing 737-800 25th January 2010 Beirut – Lebanon
• ASN Accident Description