Ethiopian Airlines Flight 409 Accident Report Considerations

Excerpt from the Official Final Investigation Report:

3.2 Causes

"3.2.1 Probable Causes

1- The flight crew mismanagement of the aircraft’s speed, altitude, heading and attitude through inconsistent flight control inputs resulting in 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.

3.2.2 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 resulted in 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 FO reluctance to intervene did not help confirming a case of captain’s subtle incapacitation and/or to take over the controls as stipulated in the operator’s SOP.”

Air Crash Investigators Anonymous Experts considerations:

I completely agree with the considerations of item 3.2.1, specially the sub-item 2. Recently the number of incidents resulting from crews not abiding to basic CRM principles have increased among airlines employing different nationalities crew members. Ethiopian Air Lines is not the first airline failing to enforce such utmost important policy. This tragedy speaks for itself, although there are more contributing factors that lead the crew to that situation that need to be taken into account.

The depicted item 3.2.2“Contributing Factors”, sub-items 3, 4, 5, 6 are nothing but the daily events of any airline and I completely disagree with their definition as “contributing factors” but for the sub-items 1 and 2. Those 2 items were induced by the airplane having entered a heavy turbulence area, which I will discuss further, but they definitely were contributing factors.

I’d consider the sub-item 4 a serious accusation of negligence to the operator’s Aviation Authority, the Manufacturer and International entities as per my knowledge the crew members fulfilled the formers requirements and were rated in the specific type, therefore I disregard it as a contributing factor.

I disregard sub-item 5 as it’s well within international regulations regarding crews flying duty times.

Sub-item 6 is doubtful as we don’t know its source. It may be only scuttlebutt.

Sub-item 7 is the result of entering the heavy turbulent area, therefore is a consequence not a contributing factor.

Sub-item 8 is mere speculation.

Sub-item 9 is a repetition of the sub-item 2 from probable cause (3.2.1).

Omitted Information

1. The report fails to recognize the approaching squall line as a contributing factor to the airplane’s demise.
2. The report fails to recognize the super cell directly above the accident site at the exact time of the accident.
3. The report fails to recognize that no pilot in his own mind would ever head his airplane direct to the heart of a thunderstorm or a super cell, therefore, denying the possibility of an on board unrecognized weather radar failure.
4. The report fails to recognize previously known issues regarding Boeing 737 Weather Radar Failures.

Conclusions

The Final Report has consistent and useful information as well as seriously important omissions, therefore leading the readers to biased conclusions.

Its failure in omitting one information (possible weather radar failure) that might have triggered all the subsequent events that lead to the tragedy is at least unusual.

References

- Excerpt from Official Report INVESTIGATION REPORT ON THE ACCIDENT OF ETHIOPIAN AIRLINES FLIGHT 409
©Republic of Lebanon-Ministry of Public Works & Transport 
- Air Crash Anonymous Experts considerations and conclusions
© Antonio Carlos Arantes De Biasi